JP5526481B2 - Secondary battery and manufacturing method thereof - Google Patents

Description

  The present invention relates to a secondary battery and a manufacturing method thereof, and more particularly to a secondary battery having a high capacity and a high output and a manufacturing method thereof.

  Secondary batteries, particularly lithium ion secondary batteries, are usually composed of a positive electrode (positive electrode layer), a liquid or solid electrolyte layer (separator layer), and a negative electrode (negative electrode layer). At this time, the positive electrode and the negative electrode are formed by mixing the positive electrode active material and the negative electrode active material with a conductive additive, a binder, and the like and applying the mixture on the current collector.

  In such a lithium ion secondary battery, as a development trend, high energy density and high output of the battery are demanded, and development of a thin battery is progressing as a countermeasure. As a technique for obtaining such a thin and light battery, there is a polymer battery in which the electrolyte portion that is a solution is made solid to reduce the thickness.

  Such a technique is already a well-known technique. However, in recent years, the improvement of characteristics has progressed, and the battery characteristics have improved to the extent that it cannot be compared with the original disclosure of the technique.

  As an example of a polymer battery, a solid polyvinylidene fluoride-based solid electrolyte medium is prepared, this is joined to a positive electrode and a negative electrode, a plasticizer is extracted from the entire battery body, and an electrolyte solution is injected. And the technique of gelling the whole. By gelling the entire battery body in this way, there is no free electrolyte in the battery. However, when a solid gelled electrolyte is used, in addition to the problem that the strength tends to be insufficient, there is a problem that it is difficult to apply a uniform thin film electrolyte.

In order to solve such a problem, for example, Patent Document 1 discusses a method of using a solid electrolyte and a separator in combination.
JP 2001-43897 A

  However, in Patent Document 1, in order to increase the capacity of the battery, the resistance due to diffusion of the polymer electrolyte increases when the thickness of the electrode exceeds a certain thickness.

  Accordingly, the present invention has been made in view of the above circumstances, and an object thereof is to provide a high-capacity and high-power secondary battery that can be easily charged and discharged with a large current.

  The present inventors have intensively studied to solve the above problems. As a result, it has been found that a battery having a high capacity and a high output can be obtained by setting the conductivity of the electrolyte of the negative electrode layer to be higher than the conductivity of at least one of the separator layer and the positive electrode layer.

  According to the present invention, since the conductivity of the electrolyte of the negative electrode layer is higher than the conductivity of the electrolyte of at least one of the separator layer and the positive electrode layer, it is possible to improve the electrolyte transport capability in the negative electrode layer. In addition, the state of high reactivity at the interface of the negative electrode can be maintained. Therefore, when the secondary battery of the present invention is used, a battery with high capacity and high output can be obtained.

  The present invention is a secondary battery including at least one single battery layer in which a positive electrode layer, a separator layer, and a negative electrode layer are laminated in this order, and the conductivity of the electrolyte of the negative electrode layer is that of the separator layer and the positive electrode layer. The present invention relates to a secondary battery having a conductivity higher than that of at least one electrolyte.

  Conventionally, the separator layer uses a liquid electrolyte in which a lithium salt as a supporting salt is dissolved in an organic solvent as a plasticizer, or a gel electrolyte in which a liquid electrolyte is injected into a matrix polymer made of an ion conductive polymer. ing. Among these, in the former case, when used for a long time, lithium precipitates during the charge cycle, which may cause an internal short circuit of the battery. For this reason, it is desirable to use a gel electrolyte for the separator layer. However, in the separator used conventionally, the mechanical strength may not be sufficient, and all of the positive electrode layer, the separator layer, and the negative electrode layer are solid. When an electrolyte is used, resistance due to diffusion of the polymer electrolyte increases. In particular, when a carbon-based material is used as the negative electrode active material, there is a problem that charging / discharging with a large current becomes difficult because the interface resistance between the active material and the polymer electrolyte is large.

  On the other hand, according to the present invention, by using an electrolyte with high conductivity as the electrolyte of the negative electrode layer having low reactivity and high resistance, the electrolyte transport capability in the negative electrode layer can be improved. In particular, when a polymer electrolyte is used for the separator layer, the separator layer and the electrolyte layer can be integrated, so that the separator layer can be made thin. Furthermore, there are few concerns about conventional problems such as lithium deposition during the charge cycle and internal short circuit of the battery.

  Therefore, the secondary battery according to the present invention can reduce the thickness of the separator layer, has a high electrolyte transport capability in the negative electrode layer, and can maintain a high reactivity at the negative electrode interface. It can be. In particular, when a liquid substance (hereinafter also referred to as “liquid electrolyte”) is used for the electrolyte of the negative electrode layer, the above advantages can be achieved more efficiently.

  The at least one single battery layer constituting the secondary battery of the present invention is formed such that the positive electrode layer and the negative electrode layer (positive electrode and negative electrode respectively) face each other, and the separator layer is disposed between the positive electrode layer and the negative electrode layer. Is arranged. At this time, at least one of the separator layer and the positive electrode layer, particularly the separator layer, is infiltrated with an electrolyte having a lower conductivity than the electrolyte of the negative electrode layer, particularly a solid electrolyte. Since the electrolyte is thus held in the structure called the separator layer, even if the electrolyte touches the electrolyte solution in the negative electrode layer, the solid electrolyte flows out due to swelling and expansion, and the electrode and separator layer thereby Separation at the interface with the substrate can be suppressed / prevented. Furthermore, the above-described conventional problems are less likely to occur by keeping the negative electrode layer and / or the positive electrode layer and the separator layer in close contact with each other. Therefore, according to the present invention, a liquid material having high reactivity and excellent ion conductivity can be used as the electrolyte of the positive electrode layer or the negative electrode layer, particularly the negative electrode layer having low reactivity and high resistance. In particular, when a polymer electrolyte is used as the electrolyte of the separator layer, the separator layer can be thinned, and the secondary battery can have higher output.

  Embodiments of the present invention will be described below.

  In the present invention, in at least one of the single battery layers constituting the secondary battery of the present invention, it is essential to set the conductivity of the electrolyte of the negative electrode layer higher than the conductivity of the electrolyte of at least one of the separator layer and the positive electrode layer. This is a configuration requirement. At this time, the conductivity of the electrolyte of the negative electrode layer may be higher than the conductivity of the electrolyte of at least one of the separator layer and the positive electrode layer, but is preferably higher than the conductivity of the electrolyte of the separator layer. Thereby, the said problem at the time of using a polymer electrolyte for a separator layer can be avoided effectively.

In the present specification, the conductivity of the electrolyte is defined as a value measured according to the method described in JIS KO102 as described in detail below. That is, the distance ("length" in the following formula) (cm) and area ("area" in the following formula) (cm ² ) between two opposing metal plates used for measurement are measured, and these The cell constant (cm ⁻¹ ) is calculated from the value of

  Further, the conductivity (S / cm) of the electrolyte is calculated using the cell constant thus calculated and the separately measured resistance (Ω).

More specifically, when measuring the conductivity of the polymer electrolyte, the polymer precursor solution is applied to the release film. Further sandwiched with a release film, sandwiched between them with a transparent glass plate, and photopolymerized to produce a polymer film of an appropriate thickness, and this polymer film is two sheets having a predetermined area with a lead wire attached Sandwiched between metal plates. The film thickness of the polymer film is measured in a state sandwiched between the two metal plates in this way, and this is defined as the length (cm). From this length and the area (cm ² ) of the metal plate, the cell constant (cm ⁻¹ ) is determined. Also, connect the lead wire to an impedance measuring instrument and measure the resistance (Ω). The conductivity (S / cm) is calculated using the cell constant (cm ⁻¹ ) and the resistance (Ω).

  In the present invention, it is preferable that the ratio of the conductivity of the electrolyte of the separator layer and the positive electrode layer to the conductivity of the electrolyte of the negative electrode layer, particularly the electrolyte of the separator layer is 1/2 to 1/100. When the ratio is ½ or less, even when an internal short circuit occurs in the battery, the short circuit current can be kept small, and the battery function can be maintained. On the other hand, if it is 1/100 or more, the electrical conductivity is appropriate, and the performance of the obtained secondary battery is sufficient.

  More preferably, the ratio of the conductivity of the electrolyte of at least one of the separator layer and the positive electrode layer to the conductivity of the electrolyte of the negative electrode layer is 1/2 to 1/50, more preferably 1/2 to 1/20. Within such a range, the short circuit of the battery does not occur, and the obtained secondary battery as a whole can exhibit sufficient battery performance.

  In the present invention, the electrolyte of the negative electrode layer is preferably a liquid material, and at least one of the separator layer and the positive electrode layer is preferably a polymer electrolyte. (1) The electrolyte of the negative electrode layer and the positive electrode layer is a liquid material, and the electrolyte of the separator layer is a polymer electrolyte; (2) The electrolyte of the negative electrode layer and the separator layer is a liquid material, and the electrolyte of the positive electrode layer Or (3) the electrolyte of the negative electrode layer is a liquid material, and the electrolyte of the separator layer and the positive electrode layer is preferably a polymer electrolyte. The above (1) and (3) are more preferable. Since the negative electrode layer has relatively low reactivity and high resistance compared to the positive electrode layer, it is preferable to use a liquid material having high reactivity and excellent ion conductivity as the electrolyte of the negative electrode layer. In the case of (1), the separator layer can be made thin, the electrolyte transport capability in the negative electrode layer is high, and the reactivity of the interface of the negative electrode can be maintained high. An output battery can be obtained. In the case of (3), since the electrolyte of the positive electrode layer is a polymer electrolyte, deterioration due to elution of the positive electrode can be effectively suppressed / prevented. When a polymer electrolyte is used as the separator layer electrolyte, the separator layer can be made thin, and the electrolyte of the negative electrode layer is a liquid material. Therefore, the electrolyte transport capability in the negative electrode layer is high, and the interface of the negative electrode layer is high. Since the reactivity can be maintained at a high level, a secondary battery having a high capacity and a high output can be obtained.

  In the present invention, the liquid substance is not particularly limited and is generally prepared by dissolving a supporting salt in a non-aqueous solvent. Here, the non-aqueous solvent is not particularly limited, and a known non-aqueous solvent (a plasticizer such as an aprotic solvent) can be used. For example, cyclic carbonates such as propylene carbonate and ethylene carbonate; chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1 Ethers such as 1,2-dibutoxyethane, 1,3-dioxolane, diethyl ether; lactones such as γ-butyrolactone; nitriles such as acetonitrile; esters such as methyl propionate; amides such as dimethylformamide; Examples include esters such as methyl and methyl formate; sulfolane; dimethyl sulfoxide; or 3-methyl-1,3-oxazolidine-2-one. The non-aqueous solvent may be used alone or in combination of two or more. The mixing ratio in the latter case is not particularly limited as long as it is a ratio capable of dissolving the supporting salt, and can be appropriately selected according to the type of non-aqueous solvent used and desired characteristics.

The supporting salt is not particularly limited, and a known supporting salt (lithium salt) can be used. For example, inorganic acid anion salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ ; LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li Examples thereof include organic acid anion salts such as (C ₂ F ₅ SO ₂ ) ₂ N, and among these, LiPF ₆ is preferably used. These supporting salts may be used alone or in combination of two or more.

  In the present invention, the polymer electrolyte is not particularly limited, but includes a gel polymer electrolyte and an intrinsic (all solid) polymer electrolyte. Here, the gel polymer electrolyte is not particularly limited, but a solid polymer electrolyte having ion conductivity containing an electrolyte used in a conventionally known lithium ion secondary battery, and lithium ion conductivity In a polymer skeleton that does not have a structure, an electrolyte solution used in a conventionally known lithium ion secondary battery is held. Examples of solid polymer electrolytes having ion conductivity include ion conductive polymers such as known solid polymer electrolytes such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. The matrix polymer etc. which become are mentioned. Such polyalkylene oxide polymers are preferred because electrolyte salts such as lithium salts can be dissolved well. Examples of the polymer having no lithium ion conductivity include polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), and polymethyl methacrylate (PMMA). However, it is not necessarily limited to these. Note that PAN, PMMA, and the like are in a class that has almost no ionic conductivity, and thus can be a polymer having the ionic conductivity. However, it is exemplified here as a polymer having no lithium ion conductivity used for the polymer gel electrolyte.

The electrolytic solution contained in the gel polymer electrolyte is not particularly limited and is generally the same as the above liquid substance, and is prepared by dissolving a supporting salt in a nonaqueous solvent. That is, the non-aqueous solvent is not particularly limited, and the same non-aqueous solvent (plasticizer such as an aprotic solvent) similar to the above can be used. The non-aqueous solvent may be used alone or in combination of two or more. The mixing ratio in the latter case is not particularly limited as long as it is a ratio capable of dissolving the supporting salt, and can be appropriately selected according to the type of non-aqueous solvent used and desired characteristics. For example, when ethylene carbonate (EC) and diethyl carbonate (DEC) are used in combination, the volume ratio of EC to the total volume of EC and DEC is 10 to 80% by volume, more preferably 20 to 60 volumes. % Is preferable. The supporting salt is not particularly limited, and the same supporting salt (lithium salt) as described above can be used. These supporting salts may be used alone or in combination of two or more. Moreover, the addition amount to the non-aqueous solvent of a support salt is not specifically limited, The same amount as before can be used. The amount is such that the molar concentration of the supporting salt in the non-aqueous solvent is preferably 0.5 to 2 mol / dm ³ . If it is such a range, sufficient reactivity (ionic conductivity) can be achieved.

  Further, the intrinsic (all solid) polymer electrolyte has a structure in which a supporting salt (lithium salt) is dissolved in the matrix polymer, and does not include an organic solvent (nonaqueous solvent) that is a plasticizer as described above. . Therefore, when constituted by an intrinsic polymer electrolyte, there is no fear of liquid leakage from the battery, and the battery reliability can be improved. The intrinsic polymer battery is a battery using a solid polymer electrolyte having ion conductivity as an electrolyte. Examples of the matrix polymer include known solid polymer electrolytes such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.

  In the present invention, the gel polymer electrolyte and the intrinsic (all solid) polymer electrolyte may be used alone or in the form of a mixture of two or more. Further, one or more of a gel polymer electrolyte and an intrinsic (all solid) polymer electrolyte may be used in combination. Further, as described in (3) above, when the separator layer and the positive electrode layer in one single battery layer are polymer electrolytes, the separator layer electrolyte and the positive electrode layer electrolyte may be the same or It may be different. Considering the ease of the manufacturing process and the like, it is preferable that they are the same. Similarly, when the secondary battery of the present invention is composed of two or more single cells, the electrolyte of the separator layer and the electrolyte of the positive electrode layer in each single cell may be the same or different. However, considering the ease of the manufacturing process, it is preferable that they are the same.

  In the present invention, it is preferable that at least the positive electrode layer and the separator layer are in close contact. This is because when the positive electrode layer and the separator layer are in close contact with each other, it is possible to suppress the outflow of the polymer due to the swelling of the polymer in the separator from the separator surface due to the leakage of the electrolyte solution of the negative electrode layer. More preferably, the positive electrode layer and the separator layer, and the negative electrode layer and the separator layer are in close contact with each other. In this way, the positive electrode layer and the separator layer, and the negative electrode layer and the separator layer are in close contact with each other, so that the electrolyte solution oozes out from the negative electrode layer or the positive electrode layer, so that the polymer in the separator is swollen from the separator surface. This is because the outflow can be further suppressed.

  In this specification, “the positive electrode layer and the separator layer are in close contact with each other” means that even when the liquid material contained in the negative electrode layer is leached, the electrolyte (particularly, polymer electrolyte) in the separator swells from the separator surface. It means a state where electrolyte does not flow out. “The positive electrode layer and the separator layer and the negative electrode layer and the separator layer are in close contact with each other” has the same meaning. Specifically, in the case of “the positive electrode layer and the separator layer are in close contact with each other”, the close contact state between the positive electrode layer and the separator layer is determined by the thickness of the laminate from the outside of the positive electrode layer and the separator layer. A state in which the positive electrode layer and the separator layer are pressed against each other by applying pressure in the direction; a state in which the positive electrode layer and the separator layer are bonded by, for example, polymerizing an adhesive or an electrolyte in the separator layer in the presence of a polymerization initiator; Is included. Of these, the positive electrode layer and the separator layer or the positive electrode layer, the separator layer, and the negative electrode layer are preferably bonded, and the positive electrode layer, the separator layer, and the negative electrode layer are more preferably bonded.

  In the present invention, when the electrode layers (positive electrode layer and negative electrode layer) include a current collector and an active material layer containing an active material formed on the current collector, the positive electrode active material layer and It is preferable that the negative electrode active material layer has a structure having a groove on the side in contact with the current collector.

  In such a form, in the step of impregnating the electrolyte when manufacturing the electrode layer, the permeability of the electrolyte (the polymer electrolyte precursor and the liquid electrolyte, which will be described later) to the central portion where the liquid is difficult to penetrate is further improved. Therefore, it is preferable. Since the polymer electrolyte precursor is less permeable to the electrolyte than the liquid electrolyte, it is preferable that the electrode layer impregnated with at least the polymer electrolyte precursor has grooves formed therein. The active material layer and the current collector will be described later.

  The shape and size of the groove are not particularly limited. For example, the cross-sectional shape of the groove is not limited as long as the electrolyte solution can easily permeate, and examples thereof include a square, a rectangle, a quadrangle, an equilateral triangle, an isosceles triangle, a triangle, a semicircular shape, and a semielliptical shape. In addition, the size of the groove is not limited as long as the electrolyte solution can easily penetrate, and the width of the groove is the average particle diameter of the positive electrode active material (in the case of the positive electrode layer) and the negative electrode active material (in the case of the negative electrode layer). It is preferable that it is 100 to 5000%. Moreover, it is preferable that the depth of a groove | channel is 100 to 200% of the average particle diameter of a positive electrode active material (in the case of a positive electrode layer) and a negative electrode active material (in the case of a negative electrode layer). In the positive electrode layer and / or the negative electrode layer, the volume ratio of the groove is preferably 5 to 30% with respect to the volume of the electrode layer [(total volume of groove / volume of electrode layer) × 100 (%) ]. With such a shape and the size of the groove, the electrolyte (liquid electrolyte, polymer electrolyte precursor, etc.) can sufficiently permeate into the central portion that is difficult to penetrate.

  In addition, the direction of formation of the groove is not limited as long as the electrolyte can easily permeate. For example, when formed in vertical and horizontal directions in a grid pattern, when formed in parallel to a certain direction, The shape is formed. Among these, it is preferable to form in a certain direction, particularly in parallel with the direction in which the electrolytic solution is injected. If it is such a direction, electrolyte solution will be smoothly poured into a groove | channel.

  The method for forming the groove is not particularly limited, and specific examples include the following methods. First, as the first layer, a slurry containing an active material is pattern-coated on the current collector surface so as to form grooves. Thereafter, a method of transferring and applying on the first layer to form the second layer can be mentioned. For pattern coating, a generally known method can be used, and examples thereof include spray coating, screen printing, and ink jet method. FIG. 6 shows a schematic diagram of this embodiment. In FIG. 6, the electrode layer 530 includes a current collector 500 and an active material layer 510 formed on the current collector 500. A first active material layer 511 is formed by pattern application. At this time, the pattern application is performed so that grooves are formed after the second active material layer application. After that, a second active material layer 512 corresponding to almost the entire area of the current collector is formed on the first active material layer by transfer coating, whereby an electrode layer 530 having a groove 520 is obtained.

  The manufacturing method of the secondary battery of the present invention is not particularly limited, and a known manufacturing method can be applied similarly or appropriately modified. Hereinafter, preferred embodiments of a method for producing a single battery layer having a structure in which the electrolyte of the positive electrode layer and the negative electrode layer is a liquid substance, the electrolyte of the separator layer is a polymer electrolyte, and the positive electrode layer, the separator layer, and the negative electrode layer are bonded to each other. Will be described in detail. Note that the method for adhering the positive electrode layer and the separator layer can be the same as the above method except that the negative electrode layer is not used, and thus the description thereof is omitted here.

  That is, the supporting salt is dissolved in a non-aqueous solvent to prepare an electrolytic solution [step (1)]. The matrix polymer, the supporting salt and the polymerization initiator as described above are added to the electrolytic solution thus prepared to prepare an electrolyte precursor solution [step (2)]. Next, after immersing the separator substrate in the electrolyte precursor solution, the excess electrolyte precursor solution is removed to obtain an impregnated separator [step (3)]. The impregnated separator is sandwiched between the positive electrode layer and the negative electrode layer, the electrolyte of the impregnated separator is polymerized, and the positive electrode layer, the separator layer, and the negative electrode layer are brought into close contact with each other [step (4)].

  In the step (1), the non-aqueous solvent is not particularly limited, and a known non-aqueous solvent (a plasticizer such as an aprotic solvent) can be used. For example, cyclic carbonates such as propylene carbonate and ethylene carbonate; chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1 Ethers such as 1,2-dibutoxyethane, 1,3-dioxolane, diethyl ether; lactones such as γ-butyrolactone; nitriles such as acetonitrile; esters such as methyl propionate; amides such as dimethylformamide; Examples include esters such as methyl and methyl formate; sulfolane; dimethyl sulfoxide; or 3-methyl-1,3-oxazolidine-2-one. The non-aqueous solvent may be used alone or in combination of two or more. The mixing ratio in the latter case is not particularly limited as long as it is a ratio capable of dissolving the supporting salt, and can be appropriately selected according to the type of non-aqueous solvent used and desired characteristics. For example, when ethylene carbonate (EC) and diethyl carbonate (DEC) are used in combination, the volume ratio of EC to the total volume of EC and DEC is 10 to 80% by volume, more preferably 20 to 60 volumes. % Is preferable.

In the step (1), the supporting salt is not particularly limited, and a known supporting salt (lithium salt) can be used. For example, inorganic acid anion salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ ; LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li Preferred examples include organic acid anion salts such as (C ₂ F ₅ SO ₂ ) ₂ N. These supporting salts may be used alone or in combination of two or more. Moreover, the addition amount to the non-aqueous solvent of a support salt is not specifically limited, The same amount as before can be used. The amount is such that the molar concentration of the supporting salt in the non-aqueous solvent is preferably 0.5 to 2 mol / dm ³ . If it is such a range, sufficient reactivity (ionic conductivity) can be achieved.

  Next, in the step (2), a matrix polymer, a supporting salt and a polymerization initiator are added to the electrolytic solution prepared in the step (1) to prepare an electrolyte precursor solution. Here, the matrix polymer is preferably a polymer electrolyte as described above, more preferably polyethylene oxide (PEO), polypropylene oxide (PPO), or a copolymer thereof, and particularly preferably polyethylene oxide (PEO). Under the present circumstances, the electrolyte of a separator layer may be used independently or may be used in mixture of 2 or more types. Further, the electrolyte of the separator layer may be the same as or different from the ion conductive polymer used for the positive electrode layer and / or the negative electrode layer of the secondary battery of the present invention described later, but it should be the same. Is preferred.

  In the said process (2), a polymerization initiator acts on the crosslinkable group of a matrix polymer (polymer electrolyte), and is mix | blended in order to advance a crosslinking reaction. Depending on the external factor for acting as an initiator, it is classified into a photopolymerization initiator, a thermal polymerization initiator and the like. Examples of the polymerization initiator include azobisisobutyronitrile (AIBN) which is a thermal polymerization initiator, benzyldimethyl ketal (BDK) which is a photopolymerization initiator, and azobis which is a thermal polymerization initiator. Isobutyronitrile (AIBN) is preferably used. The amount of the polymerization initiator added to the electrolytic solution is not particularly limited, but the polymerization initiator is 10 to 10,000 ppm by mass, more preferably about 100 to 1,000 ppm by mass with respect to the matrix polymer. It is preferable to be added.

  Next, at the said process (3), a separator base material is immersed in the electrolyte precursor solution prepared at the said process (2). In this case, the separator substrate is not particularly limited, and a known separator substrate can be used. Examples thereof include polyolefin resins such as a microporous polyethylene film, a microporous polypropylene film, and a microporous ethylene-propylene copolymer film, and porous films or nonwoven fabrics such as aramid, polyimide, and cellulose, and laminates thereof. These have the outstanding effect that the reactivity with electrolyte (electrolyte solution) can be restrained low. In addition, a composite resin film in which a polyolefin-based resin nonwoven fabric or a polyolefin-based resin porous film is used as a reinforcing material layer, and the reinforcing material layer is filled with a vinylidene fluoride resin compound may be used.

  The thickness of the separator base material may be appropriately determined according to the intended use, but may be about 1 to 100 μm in the use of a secondary battery for driving a motor such as an automobile. Further, the porosity and size of the separator base material may be appropriately determined in consideration of the characteristics of the obtained secondary battery. For example, the porosity of the separator substrate is preferably 30 to 80%, more preferably 40 to 70%. When the porosity is 40 to 70%, a battery with higher output can be obtained. The curvature of the separator base material is preferably 1.2 to 2.8. If it is a separator base material which has such porosity, sufficient quantity of electrolyte solution and the electrolyte of a separator layer can be introduce | transduced, and the intensity | strength of a separator layer can also be fully maintained.

  In addition, the conditions for immersing the separator base material in the electrolyte precursor solution are not particularly limited as long as the electrolyte precursor solution sufficiently permeates the separator base material. Specifically, the separator base material may be immersed in the electrolyte precursor solution at a temperature of 15 to 60 ° C., more preferably 20 to 50 ° C., for 1 to 120 minutes, more preferably 5 to 60 minutes. preferable. Moreover, after immersing on predetermined conditions, an excess electrolyte precursor solution is removed, However, It does not restrict | limit especially as a method which can be used in this case, A well-known method can be used. For example, a method in which a separator base material infiltrated with an electrolyte precursor solution is sandwiched between footwear films and then lightly squeezed with a roll or the like; a method in which a separator base material infiltrated with an electrolyte precursor solution is lightly squeezed can be preferably used.

  Furthermore, in the step (4), the impregnated separator obtained in the step (3) is sandwiched between the positive electrode layer and the negative electrode layer, the electrolyte of the impregnated separator is polymerized, and the positive electrode layer, the separator layer, and the negative electrode layer are adhered. In this step, by sandwiching the impregnated separator between the positive electrode layer and the negative electrode layer, a part of the electrolyte precursor solution in the impregnated separator moves to the interface between the positive electrode layer, the negative electrode layer, and the separator layer. In order to carry out polymerization in this state, electrolytes (gel electrolyte, matrix polymer of intrinsic polymer electrolyte, etc.) existing at the interface between the separator layer and the electrode layer and the separator layer form a cross-linked structure and adhere (adhere) to each other. It is considered that excellent mechanical strength can be expressed. Note that the adhesion mechanism is speculation and is not limited to the above mechanism. The polymerization method is not particularly limited as long as such a crosslinked structure can be formed. For example, the separator layer electrolyte (PEO, PPO, etc.) may be subjected to a polymerization treatment such as thermal polymerization, photopolymerization, particularly ultraviolet polymerization, radiation polymerization, or electron beam polymerization. Thermal polymerization and photopolymerization are preferable, and thermal polymerization is more preferable.

  Further, in the above step (4), after the impregnated separator is sandwiched between the positive electrode layer and the negative electrode layer, before the electrolyte of the separator layer is polymerized, the positive electrode layer-impregnated separator-negative electrode layer laminate is formed of two appropriate sheets. It is preferable to fix with a plate (for example, glass or a release film). The polymerization reaction is preferably performed in a laminate bag or the like. Thereby, the shift | offset | difference of the surface direction of a positive electrode layer-impregnation separator-negative electrode layer laminated body and the change of the film thickness of the said laminated body at the time of superposition | polymerization can be suppressed and prevented.

  In the step (4), the polymerization conditions are not particularly limited as long as the positive electrode layer, the separator layer, and the negative electrode layer can sufficiently adhere to each other. For example, in the case of thermal polymerization, the positive electrode layer-impregnated separator-negative electrode layer laminate is 20 to 150 ° C., more preferably 30 to 100 ° C., 10 minutes to 10 hours, more preferably 30 minutes to It is preferable to heat for 5 hours.

  In addition, in the said process (4), a positive electrode layer and a negative electrode layer can be formed like a well-known method except not containing electrolyte. Specifically, the positive electrode layer or the negative electrode layer includes a positive electrode active material or a negative electrode active material, and, if necessary, an electrolyte salt for increasing ion conductivity, a conductive auxiliary agent for increasing electron conductivity, and Binders and the like can be included.

Here, the positive electrode active material has a composition that occludes ions during discharge and releases ions during charge. A preferable example is a lithium-transition metal composite oxide that is a composite oxide of a transition metal and lithium. Specifically, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, Li · Mn-based composite oxide such as spinel LiMn ₂ O _4, Li · such LiFeO ₂ Fe-based composite oxides and those obtained by replacing some of these transition metals with other elements can be used. These lithium-transition metal composite oxides are excellent in reactivity and cycle characteristics, and are low-cost materials. Therefore, it is possible to form a battery having excellent output characteristics by using these materials for electrodes. In addition, examples of the positive electrode active material include transition metal oxides such as LiFePO ₄ and lithium phosphate compounds and sulfuric acid compounds; transition metal oxides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ , and sulfides. Materials; PbO ₂ , AgO, NiOOH, etc. can also be used. The positive electrode active material may be used alone or in the form of a mixture of two or more. The average particle diameter of the positive electrode active material is not particularly limited, but is preferably 1 to 100 μm, more preferably 1 to 20 μm, from the viewpoint of increasing the capacity, reactivity, and cycle durability of the positive electrode active material. Within such a range, the secondary battery can suppress an increase in the internal resistance of the battery during charging and discharging under high output conditions, and can extract a sufficient current. When the positive electrode active material is secondary particles, it can be said that the average particle diameter of the primary particles constituting the secondary particles is preferably in the range of 10 nm to 1 μm. It is not limited to. However, it goes without saying that, depending on the manufacturing method, the positive electrode active material may not be a secondary particle formed by aggregation, agglomeration, or the like. As the particle diameter of the positive electrode active material and the particle diameter of the primary particles, a median diameter obtained by using a laser diffraction method can be used. The shape of the positive electrode active material varies depending on the type and manufacturing method, and examples thereof include a spherical shape (powdered shape), a plate shape, a needle shape, a column shape, and a square shape, but are not limited thereto. Any shape can be used without any problems. Preferably, an optimal shape that can improve battery characteristics such as charge / discharge characteristics is appropriately selected.

Further, the negative electrode active material has a composition that releases ions during discharging and can store ions during charging. Examples of the negative electrode active material include metals such as Si and Sn, or metal oxides such as TiO, Ti ₂ O ₃ , TiO ₂ , SiO ₂ , SiO, and SnO ₂ , Li _4/3 Ti _5/3 O _4. Alternatively, a composite oxide of lithium and transition metal such as Li ₇ MnN, Li—Pb alloy, Li—Al alloy, Li, or natural graphite, artificial graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, Or carbon materials, such as hard carbon, are mentioned preferably. The negative electrode active material may be used alone or in the form of a mixture of two or more. The average particle size of the negative electrode active material is not particularly limited, but is preferably 1 to 100 μm, more preferably 1 to 20 μm from the viewpoint of increasing the capacity, reactivity, and cycle durability of the negative electrode active material. Within such a range, the secondary battery can suppress an increase in the internal resistance of the battery during charging and discharging under high output conditions, and can extract a sufficient current. In addition, when the negative electrode active material is secondary particles, it can be said that the average particle diameter of primary particles constituting the secondary particles is desirably in the range of 10 nm to 1 μm. It is not limited to. However, it goes without saying that, depending on the manufacturing method, the negative electrode active material may not be a secondary particle formed by aggregation, lump or the like. As the particle size of the negative electrode active material and the particle size of the primary particles, the median diameter obtained using a laser diffraction method can be used. The shape of the negative electrode active material varies depending on the type and manufacturing method, and examples thereof include a spherical shape (powdered shape), a plate shape, a needle shape, a column shape, and a square shape, but are not limited thereto. Any shape can be used without any problems. Preferably, an optimal shape that can improve battery characteristics such as charge / discharge characteristics is appropriately selected.

The electrolyte salt is not particularly limited, but BETI (lithium bis (perfluoroethylenesulfonylimide); also described as Li (C ₂ F ₅ SO ₂ ) ₂ N), LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiBOB (lithium bisoxide borate) or a mixture thereof.

  Examples of the conductive assistant include acetylene black, carbon black, ketjen black, vapor grown carbon fiber, carbon nanotube, expanded graphite, and graphite. As the binder, polyvinylidene fluoride (PVDF), SBR, polyimide, PTFE, or the like can be used. However, needless to say, the conductive assistant and the binder are not limited to these.

  The positive electrode layer and the negative electrode layer are usually formed by forming an active material layer containing an electrolyte, an electrolyte salt, a conductive additive, a binder, and the like on a suitable current collector. The material of the current collector is not particularly limited, but specific examples include, for example, iron, chromium, nickel, manganese, titanium, molybdenum, vanadium, niobium, aluminum, copper, silver, gold, platinum, and carbon. At least one current collector material selected from the group consisting of, more preferably at least one current collector material selected from the group consisting of aluminum, titanium, copper, nickel, silver, or stainless steel (SUS) These may be preferably used, and these may be used in a single layer structure (for example, in the form of a foil), may be used in a multilayer structure composed of different types of layers, or clad materials coated with these ( For example, a clad material of nickel and aluminum or a clad material of copper and aluminum may be used. Alternatively, a plating material of a combination of these current collector materials can be preferably used. Further, a current collector in which the surface of a metal (excluding aluminum) as the current collector material is coated with aluminum as another current collector material may be used. Moreover, you may use the electrical power collector which bonded together the metal foil which is two or more said electrical power collector materials depending on the case. The above materials are excellent in corrosion resistance, conductivity, workability, and the like. The general thickness of the current collector is 5 to 50 μm. However, a current collector having a thickness outside this range may be used.

  The size of the current collector is determined according to the intended use of the battery. If a large electrode used for a large battery is manufactured, a current collector having a large area is used. If a small electrode is produced, a current collector with a small area is used.

  The method for forming the positive electrode layer (or the negative electrode layer) on the surface of the current collector is not particularly limited, and known methods can be used in the same manner. For example, as described above, a positive electrode active material (or a negative electrode active material), and if necessary, an electrolyte salt for increasing ionic conductivity, a conductive assistant for increasing electronic conductivity, and a binder, A positive electrode active material liquid (or a negative electrode active material liquid) is prepared by dispersing and dissolving in an appropriate solvent. This is applied onto a current collector, dried to remove the solvent, and then pressed to form a positive electrode layer (or negative electrode layer) on the current collector. In this case, the solvent is not particularly limited, and N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylformamide, cyclohexane, hexane and the like can be used. In the case where polyvinylidene fluoride (PVDF) is employed as the binder, NMP may be used as a solvent.

  In the above method, the positive electrode active material liquid (or the negative electrode active material liquid) is applied onto the current collector, dried, and then pressed. At this time, the porosity of the positive electrode layer (or the negative electrode layer) can be controlled by adjusting the pressing conditions.

  Specific means and press conditions for the press treatment are not particularly limited, and can be appropriately adjusted so that the porosity of the positive electrode layer (or the negative electrode layer) after the press treatment becomes a desired value. Specific examples of the press process include a hot press machine and a calendar roll press machine. Also, the pressing conditions (temperature, pressure, etc.) are not particularly limited, and conventionally known knowledge can be referred to as appropriate.

  The thicknesses of the positive electrode layer and the negative electrode layer are not particularly limited, but are preferably 10 to 200 μm, particularly 20 to 100 μm. At this time, the thicknesses of the positive electrode layer and the negative electrode layer may be the same or different.

  Each of the positive electrode layer and the negative electrode layer may be a single layer or a laminate of two or more layers. When the positive electrode layer and the negative electrode layer are laminates, the number of layers is not particularly limited, and is 1 to 3 in consideration of ease of liquid electrolyte injection and ion conductivity, which will be described in detail below. It is preferable.

  When the positive electrode layer and the negative electrode layer are laminates, the positive electrode layer and the negative electrode layer are preferably composed of a plurality of layers having different porosity in the thickness direction of the negative electrode layer. Here, either one or both of the positive electrode layer and the negative electrode layer may have a structure composed of a plurality of layers having different porosity in the thickness direction of the negative electrode layer as described above. It is preferable that at least the negative electrode layer has the above structure. Such a structure is achieved by repeatedly forming the positive electrode layer and the negative electrode layer using the same method as described above.

  Generally, when injecting from the direction along the surface of the laminate, the liquid electrolyte hardly penetrates near the center of each layer. There is a possibility that a part that does not occur. For this reason, as described above, the presence of even one coarse layer along the surface can promote the penetration of the electrolytic solution in the surface direction. Since the permeation distance of the liquid is short in the depth direction of the surface, the surface can be sufficiently permeated and ion conductivity can be sufficiently secured. In addition, when the positive electrode layer and the negative electrode layer are one layer, the porosity of the layer, and in the case of a laminate of two or more layers, the porosity of each layer is preferably 30 to 60%. It is good. If the porosity of each layer is 30% or more, sufficient voids can be secured and a sufficient amount of liquid substance can be distributed. Conversely, if it is 60% or less, a sufficient capacity as a secondary battery can be secured. Further, when the electrode layer is impregnated with the polymer electrolyte precursor, the penetration of the electrolyte is similarly promoted.

  The positive electrode layer, the separator layer, and the negative electrode layer are brought into close contact with each other by the above steps (1) to (4). Next, a liquid substance (liquid electrolyte) is injected into the thus obtained positive electrode layer-separator layer-negative electrode layer laminate (liquid injection step). That is, a preferable manufacturing method of the secondary battery of the present invention includes a step of bonding a positive electrode layer, a separator layer, and a negative electrode layer to produce a laminate of the positive electrode layer, the separator layer, and the negative electrode layer, after the bonding step. And a step of injecting a liquid electrolyte into the laminate. By the above steps (1) to (4) and the liquid injection step, the electrolyte of the negative electrode layer and the positive electrode layer is a liquid substance (liquid electrolyte), and the electrolyte of the separator layer is a polymer electrolyte. A laminate is obtained. In the present invention, as described above, the electrolytes of both the negative electrode layer and the positive electrode layer need not be liquid materials. For example, when the electrolyte of the negative electrode layer is a liquid substance, but the electrolyte of the positive electrode layer is a polymer electrolyte, it can be produced as follows. First, the positive electrode layer manufactured in the same manner as described above is immersed in the electrolyte precursor solution prepared in the step (2) to form a positive electrode layer containing an electrolyte. Thereafter, in the same manner as in the above step (4), the impregnated separator obtained in the above step (3) is sandwiched between the positive electrode layer and the negative electrode layer, and the electrolyte of the impregnated separator is polymerized to obtain the positive electrode layer, the separator layer, and the negative electrode layer. Can be adhered. Or you may perform the said process (4) similarly except using the positive electrode layer produced in the state containing the electrolyte similarly to the well-known method.

  In the liquid injection step, the liquid injection method is not particularly limited as long as the liquid electrolyte can sufficiently permeate the positive electrode layer / negative electrode layer not containing the electrolyte. Specifically, a laminate of a positive electrode layer-separator layer-negative electrode layer is put in a laminate bag, and an electrolytic solution is injected into the bag; a laminate of positive electrode layer-separator layer-negative electrode layer is laminated A method of laminating and packing in a bag after filling the bag with an electrolytic solution is preferably used.

  Here, the positive electrode layer-separator layer-negative electrode layer stack is laminated in a state where the positive electrode layer, the separator layer, and the negative electrode layer are in close contact. Therefore, a method (vacuum impregnation step) in which the laminate of the positive electrode layer-separator layer-negative electrode layer is put in a laminate bag, an electrolyte solution is poured into the bag, and then laminated in a vacuum (vacuum impregnation step) is particularly preferable. By such a method, the electrolytic solution sufficiently permeates the contact portion between the positive electrode layer, the separator layer, and the negative electrode layer and the central portion where the liquid does not easily permeate.

  That is, a more preferable manufacturing method of the secondary battery of the present invention includes a step of bonding the positive electrode layer, the separator layer, and the negative electrode layer to produce a laminate of the positive electrode layer, the separator layer, and the negative electrode layer, Thereafter, a liquid electrolyte is injected into the laminated body and vacuum impregnated.

  In the liquid injection process, from the direction perpendicular to the surface of the laminate (that is, the thickness direction of the laminate) so that the thickness of the laminate of the positive electrode layer-separator layer-negative electrode layer does not change in the liquid injection process (low displacement). It is preferable to pressurize. This can be achieved, for example, by sandwiching the laminated body between two glass plates. In addition, in the said process (4), it is preferable to use for a liquid-injection process with this state put into the bag of the laminate in the state pinched | interposed with two glass plates at the time of thermal polymerization. Further, in the liquid injection process, when the pressure is applied from the direction perpendicular to the surface of the laminate (that is, in the thickness direction of the laminate), the pressure does not change the thickness of the laminate in the liquid injection process (low displacement). If it is a grade, it will not specifically limit. For example, a method of fixing two glass plates with a clip or the like so as to maintain the thickness of the laminated body; and pressing with a spring or the like can be preferably used. Specifically, the thickness of the laminate in the liquid injection step is preferably within 5% of a predetermined thickness (the length between the glass plates when the laminate is sandwiched between two glass plates), more preferably Is preferably adjusted within a range of 0.01 to 1%.

  In the present invention, in order to further improve the permeability of the electrolyte (polymer electrolyte precursor or liquid electrolyte) into the central portion, the current collector used for forming the positive electrode layer and the negative electrode layer is a foil. In the case of a flat plate shape, it is preferable to have a groove on the surface. That is, the positive electrode layer includes a positive electrode active material, and the positive electrode layer is formed on a current collector having a groove having a width and a depth of 10% or less of an average particle diameter of the positive electrode active material, and / or The negative electrode layer includes a negative electrode active material, and the negative electrode layer is formed on a current collector having a groove having a width and depth of 10% or less of an average particle diameter of the negative electrode active material on a surface of the negative electrode layer. preferable. When the current collector has a groove, the shape and size of the groove are not particularly limited. For example, the cross-sectional shape of the groove is not limited as long as the electrolyte solution can easily permeate, and examples thereof include a square, a rectangle, a quadrangle, an equilateral triangle, an isosceles triangle, a triangle, a semicircular shape, and a semielliptical shape. Further, the size of the groove is not limited as long as the electrolyte can easily penetrate, and the width of the groove is the average particle diameter of the positive electrode active material (in the case of the positive electrode layer) and the negative electrode active material (in the case of the negative electrode layer). It is preferable that it is 10% or less. Moreover, it is preferable that the depth of a groove | channel is 10% or less of the average particle diameter of a positive electrode active material (in the case of a positive electrode layer) and a negative electrode active material (in the case of a negative electrode layer). Moreover, the volume ratio [(groove total volume / current collector volume) × 100 (%)] occupied by the grooves in the current collector is preferably 1 to 30%. With such a shape and the size of the groove, the electrolyte can sufficiently penetrate into the central portion that is difficult to penetrate. Further, the formation direction of the grooves of the current collector is not limited as long as the electrolyte is easy to penetrate, for example, when formed in a vertical and horizontal direction in a grid pattern, when formed in parallel to a certain direction, For example, it may be formed in a honeycomb shape (hexagonal shape). Among these, it is preferable to form in a certain direction, particularly parallel to the direction of liquid injection. In such a direction, the electrolyte is smoothly poured into the groove.

  Moreover, the liquid electrolyte used at the said liquid injection process is not restrict | limited in particular, For example, the electrolyte solution in the said process (1) can be used similarly. That is, the liquid electrolyte is prepared by dissolving a supporting salt in a nonaqueous solvent. Examples of the non-aqueous solvent that can be used in the liquid injection step include cyclic carbonates such as propylene carbonate and ethylene carbonate; chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; tetrahydrofuran, 2-methyltetrahydrofuran, 1 Ethers such as 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, 1,3-dioxolane, diethyl ether; lactones such as γ-butyrolactone; nitriles such as acetonitrile; methyl propionate Esters such as dimethylformamide; esters such as methyl acetate and methyl formate; sulfolane; dimethyl sulfoxide; or 3-methyl-1,3-oxazolidine-2-one It is. Preferably, ethylene carbonate and diethyl carbonate are used. The non-aqueous solvent may be used alone or in combination of two or more. The mixing ratio in the latter case is not particularly limited as long as it is a ratio capable of dissolving the supporting salt, and can be appropriately selected according to the type of non-aqueous solvent used and desired characteristics. For example, when ethylene carbonate (EC) and diethyl carbonate (DEC) are used in combination, the volume ratio of EC to the total volume of EC and DEC is 10 to 80% by volume, more preferably 20 to 60 volumes. % Is preferable.

The supporting salt is not particularly limited, and a known supporting salt (lithium salt) can be used. For example, inorganic acid anion salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ ; LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li Preferred examples include organic acid anion salts such as (C ₂ F ₅ SO ₂ ) ₂ N. These supporting salts may be used alone or in combination of two or more. Moreover, the addition amount to the non-aqueous solvent of a support salt is not specifically limited, The same amount as before can be used. The amount is such that the molar concentration of the supporting salt in the non-aqueous solvent is preferably 0.5 to 2 mol / dm ³ . If it is such a range, sufficient reactivity (ionic conductivity) can be achieved.

  The secondary battery of the present invention includes at least one single battery produced as described above. The cell according to the present invention is housed in a battery case or the like. As the battery case, it is preferable to use a battery case that can prevent external impact and environmental degradation when the battery is used. For example, a battery case made of a laminate material in which a polymer film and a metal foil are laminated together is joined to the periphery thereof by heat sealing. Alternatively, the opening formed in the bag shape is hermetically sealed by heat fusion, and the positive electrode lead terminal and the negative electrode lead terminal are taken out from the heat fusion portion. At this time, the location where the lead terminals of the positive and negative electrodes are taken out is not particularly limited to one location. Moreover, the material which comprises a battery case is not limited to the above-mentioned thing, The material by plastics, a metal, rubber | gum, etc., or these combination is possible, and things, such as a film, a board, and a box shape, can be used for a shape. In addition, a method of providing a terminal that conducts between the inside and outside of the case, connecting a current collector inside the terminal, and connecting a lead terminal outside the terminal to take out current can be applied.

  The structure of the secondary battery of the present invention is not particularly limited, and when it is distinguished by the form and structure, any conventionally known form such as a stacked (flat) battery or a wound (cylindrical) battery is used.・ Applicable to structures. Further, when viewed in terms of electrical connection form (electrode structure) in a lithium ion secondary battery, it can be applied to both (internal parallel connection type) batteries and bipolar (internal series connection type) batteries. .

  In the present invention, long-term reliability can be ensured by a simple sealing technique such as thermocompression bonding by adopting a laminated (flat) battery structure, which is advantageous in terms of cost and workability.

  Therefore, in the following description, the (internal parallel connection type) lithium ion secondary battery and the bipolar type (internal series connection type) lithium ion secondary battery of the present invention will be described very simply with reference to the drawings. Should not be limited to.

  FIG. 1 shows a flat type (stacked type) lithium ion secondary battery (hereinafter simply referred to as a non-bipolar lithium ion secondary battery or a non-bipolar type secondary battery), which is a typical embodiment of the lithium ion battery of the present invention. 1 is a schematic cross-sectional view schematically showing the entire structure of a secondary battery.

  As shown in FIG. 1, in the non-bipolar lithium ion secondary battery 10 of the present embodiment, a laminate film in which a polymer-metal composite is used for the battery exterior material 22 is used. And it has the structure which accommodated the electric power generation element (battery element) 17, and was sealed by joining all the peripheral parts of a laminate film by heat sealing | fusion. Here, the power generation element (battery element) 17 includes a positive electrode plate in which positive electrodes (positive electrode active material layers) 12 are formed on both surfaces of the positive electrode current collector 11, a separator layer 13, and negative electrodes ( The negative electrode plate on which the negative electrode active material layer) 15 is formed is laminated. At this time, the positive electrode (positive electrode active material layer) 12 on one surface of one positive electrode plate and the negative electrode (negative electrode active material layer) 15 on one surface of one negative electrode plate adjacent to the one positive electrode plate face each other through the separator layer 13. Thus, a plurality of positive electrodes, separator layers 13 and negative electrodes are stacked in this order.

  As a result, the adjacent positive electrode (positive electrode active material layer) 12, separator layer 13, and negative electrode (negative electrode active material layer) 15 constitute one unit cell layer 16. Therefore, it can be said that the lithium ion secondary battery 10 of the present embodiment has a configuration in which a plurality of single battery layers 16 are stacked and electrically connected in parallel. Note that the positive electrode (positive electrode active material layer) 12 is formed only on one side of the outermost layer positive electrode current collector 11 a located in both outermost layers of the power generation element (battery element; laminate) 17. In addition, by changing the arrangement of the positive electrode plate and the negative electrode plate in FIG. 1, the outermost negative electrode current collector (not shown) is positioned in both outermost layers of the power generation element (battery element) 17, and the outermost layer negative electrode Also in the case of the current collector, the negative electrode (negative electrode active material layer) 15 may be formed only on one side.

  Further, the positive electrode tab 18 and the negative electrode tab 19 that are electrically connected to the respective electrode plates (positive electrode plate and negative electrode plate) are connected to the positive electrode current collector 11 and the negative electrode of each electrode plate via the positive electrode terminal lead 20 and the negative electrode terminal lead 21. It is attached to the current collector 14 by ultrasonic welding, resistance welding, or the like, and has a structure that is sandwiched between the heat fusion parts and exposed to the outside of the battery exterior material 22.

  FIG. 2 shows another typical embodiment of the lithium ion battery of the present invention, a bipolar flat type (stacked type) lithium ion secondary battery (hereinafter simply referred to as a bipolar lithium ion secondary battery, or bipolar). 1 is a schematic cross-sectional view schematically showing the entire structure of a secondary battery.

  As shown in FIG. 2, in the bipolar lithium ion secondary battery 30 of the present embodiment, a substantially rectangular power generation element (battery element) 37 in which a charge / discharge reaction actually proceeds is sealed inside the battery exterior material 42. Has a structured. As shown in FIG. 2, the power generation element (battery element) 37 of the bipolar secondary battery 30 of the present embodiment is adjacent to each other with a separator layer 35 sandwiched between bipolar electrodes 34 composed of one or more sheets. A positive electrode (positive electrode active material layer) 32 and a negative electrode (negative electrode active material layer) 33 of the bipolar electrode 34 are opposed to each other. Here, the bipolar electrode 34 has a structure in which a positive electrode (positive electrode active material layer) 32 is provided on one surface of the current collector 31 and a negative electrode (negative electrode active material layer) 33 is provided on the other surface. That is, in the bipolar secondary battery 30, a bipolar electrode having a positive electrode (positive electrode active material layer) 32 on one surface of the current collector 31 and a negative electrode (negative electrode active material layer) 33 on the other surface. A power generation element (battery element) 37 having a structure in which a plurality of sheets 34 are stacked via a separator layer 35 is provided.

  The adjacent positive electrode (positive electrode active material layer) 32, separator layer 35, and negative electrode (negative electrode active material layer) 33 constitute one single battery layer (= battery unit or single cell). Therefore, it can be said that the bipolar secondary battery 30 has a configuration in which the single battery layers 36 are stacked. In addition, a seal portion (insulating layer) 43 is disposed around the unit cell layer 36 in order to prevent liquid junction due to leakage of the electrolyte from the separator layer 35. By providing the seal portion (insulating layer) 43, the adjacent current collectors 31 can be insulated and a short circuit due to contact between the adjacent electrodes (the positive electrode 32 and the negative electrode 33) can be prevented.

  The positive electrode 34a and the negative electrode 34b located in the outermost layer of the power generation element (battery element) 37 may not have a bipolar electrode structure, and are necessary for the current collectors 31a and 31b (or terminal plates). It is good also as a structure which has arrange | positioned the positive electrode (positive electrode active material layer) 32 or the negative electrode (negative electrode active material layer) 33 of only one side. A positive electrode (positive electrode active material layer) 32 may be formed on only one side of the positive electrode side outermost layer current collector 31 a located in the outermost layer of the power generation element (battery element) 37. Similarly, a negative electrode (negative electrode active material layer) 33 may be formed only on one side of the outermost current collector 31b on the negative electrode side located in the outermost layer of the power generation element (battery element) 37. In the bipolar lithium ion secondary battery 30, the positive electrode tab 38 and the negative electrode tab 39 are provided on the positive electrode side outermost layer current collector 31 a and the negative electrode side outermost layer current collector 31 b at both the upper and lower ends, respectively. 40 and the negative terminal lead 41 are joined. However, the positive electrode side outermost layer current collector 31 a may be extended to form a positive electrode tab 38, and may be derived from a laminate sheet that is the battery exterior material 42. Similarly, the negative electrode side outermost layer current collector 31b may be extended to form a negative electrode tab 39, which may be similarly derived from a laminate sheet that is the battery outer packaging material 42.

  In the bipolar lithium ion secondary battery 30, the power generation element (battery element; laminated body) 37 portion is used as a battery exterior material (exterior package) 42 in order to prevent external impact and environmental degradation during use. It is preferable to have a structure in which the positive electrode tab 38 and the negative electrode tab 39 are taken out of the battery exterior material 42 by being sealed under reduced pressure. The basic configuration of the bipolar lithium ion secondary battery 30 can be said to be a configuration in which a plurality of stacked single battery layers (single cells) 36 are connected in series.

  As described above, regarding each constituent requirement and manufacturing method of the non-bipolar lithium ion secondary battery and the bipolar lithium ion secondary battery, the electrical connection form (electrode structure) in the lithium ion secondary battery is different. Except for this, it is basically the same. Moreover, an assembled battery and a vehicle can also be comprised using the non-bipolar lithium ion secondary battery and / or bipolar lithium ion secondary battery of this invention.

[Appearance structure of lithium ion secondary battery]
FIG. 3 is a perspective view showing an appearance of a stacked flat non-bipolar or bipolar lithium ion secondary battery which is a typical embodiment of the lithium ion battery according to the present invention.

  As shown in FIG. 3, the stacked flat lithium ion secondary battery 50 has a rectangular flat shape, and a positive electrode tab 58 and a negative electrode tab 59 for taking out electric power from both sides thereof. Has been pulled out. The power generation element (battery element) 57 is wrapped by the battery outer packaging material 52 of the lithium ion secondary battery 50, and the periphery thereof is heat-sealed. The power generation element (battery element) 57 includes a positive electrode tab 58 and a negative electrode tab 59. It is sealed in a state where it is pulled out to the outside. Here, the power generation element (battery element) 57 corresponds to the power generation elements (battery elements) 17 and 37 of the non-bipolar or bipolar lithium ion secondary batteries 10 and 30 shown in FIG. 1 or FIG. To do. In addition, a plurality of single battery layers (single cells) 16 and 36 composed of positive electrodes (positive electrode active material layers) 12 and 32, separator layers 13 and 35, and negative electrodes (negative electrode active material layers) 15 and 33 are laminated. is there.

  The lithium ion battery of the present invention is not limited to the stacked flat shape as shown in FIGS. The wound lithium ion battery may have a cylindrical shape, or may be a rectangular flat shape obtained by deforming such a cylindrical shape. In the said cylindrical shape thing, a laminate film may be used for the exterior material, and the conventional cylindrical can (metal can) may be used, for example, It does not restrict | limit.

  Also, the removal of the tabs 58 and 59 shown in FIG. 3 is not particularly limited. The positive electrode tab 58 and the negative electrode tab 59 may be drawn out from the same side, or the positive electrode tab 58 and the negative electrode tab 59 may be divided into a plurality of parts and taken out from each side, as shown in FIG. It is not limited to. Further, in a wound type lithium ion battery, instead of a tab, for example, a terminal may be formed using a cylindrical can (metal can).

  The lithium ion battery of the present invention is used as a power source for driving a vehicle or an auxiliary power source that requires a high volume energy density and a high volume output density as a large capacity power source for an electric vehicle, a hybrid electric vehicle, a fuel cell vehicle, a hybrid fuel cell vehicle, etc. It can be suitably used.

[Battery]
The assembled battery of the present invention is formed by connecting a plurality of lithium ion secondary batteries of the present invention. Specifically, at least two or more are used, and are configured by serialization, parallelization, or both. Capacitance and voltage can be freely adjusted by paralleling in series. In the assembled battery of the present invention, the non-bipolar lithium ion secondary battery and the bipolar lithium ion secondary battery of the present invention are used, and these are combined in series, in parallel, or in series and in parallel. Thus, an assembled battery can also be configured.

  4 is an external view of a typical embodiment of the assembled battery according to the present invention, FIG. 4A is a plan view of the assembled battery, FIG. 4B is a front view of the assembled battery, and FIG. It is a side view of an assembled battery.

  As shown in FIG. 4, an assembled battery 300 according to the present invention forms a small assembled battery 250 that can be attached and detached by connecting a plurality of lithium ion secondary batteries of the present invention in series or in parallel. A large capacity and large output suitable for a vehicle driving power source and an auxiliary power source that require a high volume energy density and a high volume output density by connecting a plurality of these detachable small assembled batteries 250 in series or in parallel. It is also possible to form an assembled battery 300 having 4A is a plan view of the assembled battery, FIG. 4A is a front view, and FIG. 4C is a side view. The small assembled battery 250 that can be attached / detached has an electrical connection means such as a bus bar. The assembled battery 250 is stacked in a plurality of stages using the connection jig 310. How many non-bipolar or bipolar lithium ion secondary batteries are connected to produce the assembled battery 250, and how many assembled batteries 250 are stacked to produce the assembled battery 300 are mounted. What is necessary is just to determine according to the battery capacity and output of the vehicle (electric vehicle) to be.

[vehicle]
The vehicle of the present invention is characterized in that the lithium ion battery of the present invention or an assembled battery formed by combining a plurality of these is mounted. When the high-capacity positive electrode of the present invention is used, a battery having a high energy density can be configured. Therefore, when such a battery is mounted, a plug-in hybrid electric vehicle having a long EV travel distance or an electric vehicle having a long charge travel distance can be configured. In other words, the lithium ion battery of the present invention or an assembled battery formed by combining a plurality of these can be used as a power source for driving a vehicle. Examples of vehicles include hybrid vehicles, fuel cell vehicles, and electric vehicles (all are automobiles (commercial vehicles such as passenger cars, trucks, buses, light vehicles, etc.), motorcycles, and tricycles. ). However, the application is not limited to automobiles, and it can be applied to various power sources for other vehicles, for example, moving bodies such as trains, and can be used as a power source for mounting such as an uninterruptible power supply. It is also possible to do.

  FIG. 5 is a conceptual diagram of a vehicle equipped with the assembled battery of the present invention.

  As shown in FIG. 5, in order to mount the assembled battery 300 on a vehicle such as the electric vehicle 400, the battery pack 300 is mounted under the seat at the center of the vehicle body of the electric vehicle 400. This is because if it is installed under the seat, the interior space and the trunk room can be widened. The place where the assembled battery 300 is mounted is not limited to the position under the seat, but may be a lower part of the rear trunk room or an engine room in front of the vehicle. The electric vehicle 400 using the assembled battery 300 as described above has high durability and can provide sufficient output even when used for a long period of time. Furthermore, it is possible to provide electric vehicles and hybrid vehicles that are excellent in fuel efficiency and running performance. A vehicle equipped with the assembled battery of the present invention can be widely applied to a hybrid vehicle, a fuel cell vehicle and the like in addition to an electric vehicle as shown in FIG.

  The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

<Example 1>
Production of positive electrode layer LiMn ₂ O ₄ (average particle diameter: 10 μm) (90 parts by mass) as a positive electrode active material, carbon black (6 parts by mass) as a conductive additive, and polyvinylidene fluoride (PVDF # 1300) as a binder (4 parts by mass) was mixed. The mixture was used as a positive electrode mixture, and N-methyl-2-pyrrolidone (50 parts by mass) was dispersed as a solvent to obtain a slurry. The slurry thus obtained was applied onto an aluminum (Al) foil as a current collector having a thickness of 20 μm so that the final positive electrode layer had a thickness of 70 μm, pressed, dried, A positive electrode layer was obtained.

Production of Negative Electrode Layer Artificial graphite powder (average particle size: 10 μm) (90 parts by mass) as a negative electrode active material and polyvinylidene fluoride (PVDF # 9200) (10 parts by mass) as a binder are N-methyl-2- Pyrrolidone (50 parts by mass) was dispersed as a solvent to obtain a slurry. The slurry thus obtained was coated, dried and pressed on a 20 μm copper (Cu) foil as a negative electrode current collector so that the final negative electrode layer had a thickness of 40 μm. did.

Preparation of Electrolytic Solution Using ethylene carbonate (30 parts by volume) and diethyl carbonate (70 parts by volume) as a mixed solvent, LiPF ₆ was added as a solute at a ratio of 1 mol · dm ⁻³ to prepare a nonaqueous electrolytic solution.

Preparation of Solid Electrolyte Precursor Solution 40% by Mass—Polyethylene Oxide as Polymer Electrolyte / 60% by Mass—Azobisiso as a thermal polymerization initiator equivalent to 5000 ppm by mass with respect to the polymer electrolyte Butyronitrile (AIBN) was added to prepare a solid electrolyte precursor solution.

  A polyolefin film (made of polyethylene (PE), thickness 10 μm, porosity 45%, curvature 1.5) as a separator substrate is immersed in a container filled with the solid electrolyte precursor solution obtained above. And vacuum impregnation at room temperature for 1 hour. Thereafter, the polyolefin film was sandwiched between the footwear films and lightly squeezed with a roll to remove the excess solid electrolyte precursor solution, thereby obtaining an impregnated separator. Further, the impregnated separator is sandwiched between the positive electrode layer and the negative electrode layer prepared above, put into a laminate bag, and then sandwiched (fixed) between two glass plates from both sides, and then in an oven at 80 ° C. for 3 hours. And a thermal polymerization was performed to obtain a laminate of positive electrode layer-separator layer-negative electrode layer. As a result, the contact surface of each layer is brought into close contact (adhesion) by polymerization of the solid electrolyte precursor. Moreover, the electrolyte solution is not contained in the positive electrode layer and the negative electrode layer at this time.

  Thereafter, the electrolyte layer was poured while the laminate of the positive electrode layer-separator layer-negative electrode layer was sandwiched between the two glass plates as described above, and then laminated in a vacuum to produce a laminated secondary battery.

In the laminated secondary battery thus obtained, the electrolyte of the negative electrode layer and the positive electrode layer is a liquid material, and the electrolyte of the separator layer is a polymer electrolyte. A liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) was used for the negative electrode layer and the positive electrode layer of the stacked secondary battery. Moreover, the gel polymer electrolyte whose electrical conductivity is 6 * 10 < ^-4 > (S / cm) was used for the separator layer. Thus, it can be seen that the separator layer is in a state in which the gel polymer electrolyte having a lower electrical conductivity is infiltrated (held) than the liquid electrolyte infiltrated into the positive electrode layer or the negative electrode layer.

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Charge / discharge characteristics test>
Charging / discharging test is 1: constant current charging (charging to a predetermined voltage with a predetermined current. After that, the charging time is held so that the total charging time is 15 hours.) 2: pause (pause for 10 minutes) 3: Constant voltage discharge (discharged to a predetermined voltage with a predetermined current) 4: Pause (pause for 10 minutes). The charging current is 0.1 C, the charging voltage is 4.2 V, and the discharging voltage is 2 V. Here, 1C is a current value at which the battery is fully charged (100% charged) when charged at that current value for 1 hour. For example, 2C is a current value that is twice that of 1C, and is a current value that can fully charge the battery in 30 minutes. In addition, the discharge current in the first cycle was 0.2C, the second cycle was 0.5C, and the third and subsequent cycles were 0.2C.

  Discharge efficiency is the ratio of the discharge capacity when using a polymer electrolyte when the discharge capacity when using only a liquid electrolyte as the electrolyte and charging at 0.1 C and discharging at 0.2 C is 100%. did. That is, the discharge efficiency is expressed by the following formula; discharge efficiency (%) = [(discharge capacity when using polymer electrolyte) / (discharge capacity when using only liquid electrolyte as electrolyte)] × 100. .

<Example 2>
In the same manner as described in Example 1, a positive electrode layer was produced. The positive electrode layer thus prepared was immersed in a container filled with a solid electrolyte precursor solution prepared in the same manner as described in Example 1, and vacuum impregnated at room temperature for 1 hour. Thereafter, the positive electrode layer was sandwiched between the footwear films and lightly squeezed with a roll to remove the excess solid electrolyte precursor solution to obtain an impregnated positive electrode layer.

  Except for using the impregnated positive electrode layer thus produced as the positive electrode layer, thermal polymerization was performed in the same manner as in Example 1 to obtain a laminate of the positive electrode layer-separator layer-negative electrode layer. As a result, the contact surface of each layer is brought into close contact (adhesion) by polymerization of the solid electrolyte precursor. In addition, the negative electrode layer at this time does not contain an electrolyte.

  Thereafter, in the same manner as in the method described in Example 1, a laminated secondary battery was produced.

In the laminated secondary battery thus obtained, the electrolyte of the negative electrode layer is a liquid material, and the electrolyte of the separator layer and the positive electrode layer is a polymer electrolyte. In addition, a liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) was used for the negative electrode layer of the stacked secondary battery. Moreover, the gel polymer electrolyte whose electrical conductivity is 6 * 10 < ^-4 > (S / cm) was used for the separator layer and the positive electrode layer. Thus, it can be seen that the separator polymer and the positive electrode layer are in a state where the gel polymer electrolyte having a lower conductivity than the liquid electrolyte soaked in the negative electrode layer is soaked (held).

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Example 3>
Production of positive electrode layer LiMn ₂ O ₄ (average particle size: 10 μm) (90 parts by mass) as a positive electrode active material, carbon black (6 parts by mass) as a conductive additive, and polyvinylidene fluoride (PVDF # 1300) as a binder (4 parts by mass) was mixed. The mixture was used as a positive electrode mixture, and N-methyl-2-pyrrolidone (50 parts by mass) was dispersed as a solvent to obtain a slurry. The slurry thus obtained was applied to a current collector aluminum (Al) foil having a thickness of 20 μm, dried and pressed so that the final positive electrode layer had a thickness of 36 μm. One positive electrode layer was formed. At this time, the porosity of the first positive electrode layer was 35%. Next, a slurry similar to the above is applied onto the first positive electrode layer so that the final positive electrode layer has a thickness of 40 μm, and is pressed at a lower pressing pressure than that at the time of preparing the first positive electrode layer, and then dried. And it was set as the 2nd positive electrode layer. At this time, the porosity of the second positive electrode layer was 40%.

Production of Negative Electrode Layer Artificial graphite powder (average particle size: 10 μm) (90 parts by mass) as a negative electrode active material and polyvinylidene fluoride (PVDF # 9200) (10 parts by mass) as a binder are N-methyl-2- Pyrrolidone (50 parts by mass) was dispersed as a solvent to obtain a slurry. The slurry thus obtained was applied onto a negative electrode current collector copper (Cu) foil having a thickness of 20 μm so that the final negative electrode layer had a thickness of 20 μm, and press-dried. One negative electrode layer was formed. At this time, the porosity of the first negative electrode layer was 35%. Next, a slurry similar to the above is applied onto the first negative electrode layer so that the final negative electrode layer has a thickness of 25 μm, and is pressed at a lower pressing pressure than that at the time of preparing the first negative electrode layer, and then dried. And it was set as the 2nd negative electrode layer. At this time, the porosity of the second negative electrode layer was 40%.

  A multilayer secondary battery was produced in the same manner as in Example 1 except that the positive electrode layer and the negative electrode layer thus produced were used.

In the laminated secondary battery thus obtained, the electrolyte of the negative electrode layer and the positive electrode layer is a liquid material, and the electrolyte of the separator layer is a polymer electrolyte. A liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) was used for the negative electrode layer and the positive electrode layer of the stacked secondary battery. Moreover, the gel polymer electrolyte whose electrical conductivity is 6 * 10 < ^-4 > (S / cm) was used for the separator layer. Thus, it can be seen that the separator layer is in a state in which the gel polymer electrolyte having a lower electrical conductivity is infiltrated (held) than the liquid electrolyte infiltrated into the positive electrode layer or the negative electrode layer.

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Example 4>
In Example 2, a laminated secondary battery was produced in the same manner as in Example 2 except that the positive electrode layer and the negative electrode layer used in Example 3 were used.

In the laminated secondary battery thus obtained, the electrolyte of the negative electrode layer is a liquid material, and the electrolyte of the separator layer and the positive electrode layer is a polymer electrolyte. In addition, a liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) was used for the negative electrode layer of the stacked secondary battery. Moreover, the gel polymer electrolyte whose electrical conductivity is 6 * 10 < ^-4 > (S / cm) was used for the separator layer and the positive electrode layer. Thus, it can be seen that the separator polymer and the positive electrode layer are in a state where the gel polymer electrolyte having a lower conductivity than the liquid electrolyte soaked in the negative electrode layer is soaked (held).

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Example 5>
In Example 1, an aluminum (Al) foil (thickness: 1 μm in width and 1 μm in depth) on the surface having grooves for infiltrating an electrolyte solution at a 1 μm interval so that the volume ratio to the current collector is 2.5%. 20 μm) was used to produce a positive electrode layer. Further, in Example 1, a copper (Cu) foil (thickness) having grooves for infiltrating an electrolyte solution having a width of 1 μm and a depth of 1 μm on the surface so that the volume ratio to the current collector becomes 2.5% at intervals of 1 μm. Sa: 20 μm) was used to prepare a negative electrode layer. Except for this, a multilayer secondary battery was produced in the same manner as in Example 1. In this example, the positive electrode layer—the separator layer—so that the grooves in the current collector (aluminum (Al) foil and copper (Cu) foil) are parallel to the injection direction of the electrolytic solution. The laminate of the negative electrode layer was placed in a laminate bag.

In the laminated secondary battery thus obtained, the electrolyte of the negative electrode layer and the positive electrode layer is a liquid material, and the electrolyte of the separator layer is a polymer electrolyte. A liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) was used for the negative electrode layer and the positive electrode layer of the stacked secondary battery. Moreover, the gel polymer electrolyte whose electrical conductivity is 6 * 10 < ^-4 > (S / cm) was used for the separator layer. Thus, it can be seen that the separator layer is in a state in which the gel polymer electrolyte having a lower electrical conductivity is infiltrated (held) than the liquid electrolyte infiltrated into the positive electrode layer or the negative electrode layer.

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Example 6>
In Example 2, an aluminum (Al) foil (thickness: 1 μm in width and 1 μm in depth) on the surface having grooves for infiltrating an electrolyte solution at a 1 μm interval so that the volume ratio to the current collector is 2.5%. 20 μm) was used to make a negative electrode layer. Further, in Example 2, a copper (Cu) foil (thickness) having grooves for infiltrating an electrolyte solution having a width of 1 μm and a depth of 1 μm on the surface so that the volume ratio to the current collector becomes 2.5% at intervals of 1 μm. Sa: 20 μm) was used to prepare a negative electrode layer. Except for this, a multilayer secondary battery was produced in the same manner as in Example 2.

In the laminated secondary battery thus obtained, the electrolyte of the negative electrode layer is a liquid material, and the electrolyte of the separator layer and the positive electrode layer is a polymer electrolyte. Moreover, the gel polymer electrolyte whose electrical conductivity is 6 * 10 < ^-4 > (S / cm) was used for the separator layer and the positive electrode layer. Thus, it can be seen that the separator polymer and the positive electrode layer are in a state where the gel polymer electrolyte having a lower conductivity than the liquid electrolyte soaked in the negative electrode layer is soaked (held).

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Example 7>
Production of positive electrode layer LiMn ₂ O ₄ (average particle diameter: 10 μm) (90 parts by mass) as a positive electrode active material, carbon black (6 parts by mass) as a conductive additive, and polyvinylidene fluoride (PVDF # 1300) as a binder (4 parts by mass) was mixed. The mixture was used as a positive electrode mixture, and N-methyl-2-pyrrolidone (50 parts by mass) was dispersed as a solvent to obtain a slurry. A current collector having a thickness of 20 μm was formed from the slurry thus obtained so that a groove for penetration of an electrolyte solution having a width of 10 μm and a depth of 10 μm (volume ratio of 6.25% with respect to the electrode layer) was formed. A pattern was applied on an aluminum (Al) foil. Thereafter, a groove was formed on the layer formed by pattern coating by further transfer coating, and then pressed and dried so that the final thickness of the positive electrode layer was 80 μm, thereby producing a positive electrode layer. .

Production of Negative Electrode Layer Artificial graphite powder (average particle size: 10 μm) (90 parts by mass) as a negative electrode active material and polyvinylidene fluoride (PVDF # 9200) (10 parts by mass) as a binder are N-methyl-2- Pyrrolidone (50 parts by mass) was dispersed as a solvent to obtain a slurry. The slurry thus obtained was provided with a groove (10% volume ratio with respect to the electrode layer) for impregnating an electrolyte having a width of 10 μm and a depth of 10 μm on a negative electrode current collector of 20 μm copper (Cu) foil. It was produced by pattern coating. Thereafter, a groove was formed on the layer formed by pattern coating by transfer coating, and then pressed and dried so that the final negative electrode layer had a thickness of 50 μm, thereby preparing a negative electrode layer. In addition, the positive electrode layer-separator layer-negative electrode layer laminate was placed in a laminate bag so that the groove in the electrode was parallel to the electrolyte injection direction.

  A multilayer secondary battery was produced in the same manner as in Example 1 except that the positive electrode layer and the negative electrode layer thus produced were used.

In the laminated secondary battery thus obtained, the electrolyte of the negative electrode layer and the positive electrode layer is a liquid material, and the electrolyte of the separator layer is a polymer electrolyte. A liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) was used for the negative electrode layer and the positive electrode layer of the stacked secondary battery. Moreover, the gel polymer electrolyte whose electrical conductivity is 6 * 10 < ^-4 > (S / cm) was used for the separator layer. Thus, it can be seen that the separator layer is in a state in which the gel polymer electrolyte having a lower electrical conductivity is infiltrated (held) than the liquid electrolyte infiltrated into the positive electrode layer or the negative electrode layer.

  The secondary battery thus produced was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 and FIG.

<Example 8>
In Example 2, a battery was produced in the same manner as in Example 2 except that the positive electrode layer and the negative electrode layer produced in Example 7 were used.

In the laminated secondary battery thus obtained, the electrolyte of the negative electrode layer is a liquid material, and the electrolyte of the separator layer and the positive electrode layer is a polymer electrolyte. In addition, a liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) was used for the negative electrode layer of the stacked secondary battery. Moreover, the gel polymer electrolyte whose electrical conductivity is 6 * 10 < ^-4 > (S / cm) was used for the separator layer and the positive electrode layer. Thus, it can be seen that the separator polymer and the positive electrode layer are in a state where the gel polymer electrolyte having a lower conductivity than the liquid electrolyte soaked in the negative electrode layer is soaked (held).

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Comparative Example 1>
In Example 1, the positive electrode layer and the negative electrode layer were also impregnated with vacuum at room temperature for 1 hour in the same manner as the polyolefin film, sandwiched between the negative electrode layer and the polyolefin film with the footwear film, lightly rubbed with a roll, and excess solids The electrolyte electrolyte precursor solution is removed. It is overlapped with the dried negative electrode layer, put into a laminate bag, sandwiched between glass plates from both sides, and subjected to thermal polymerization in an oven at 80 ° C. for 3 hours under pressure. At this time, the positive electrode layer, the separator layer, and the negative electrode layer are in close contact. Thereafter, a secondary battery was produced in the same manner as in Example 1. For the positive electrode layer, the separator layer, and the negative electrode layer, a gel polymer electrolyte having a conductivity of 6 × 10 ⁻⁴ (S / cm) was used.

<Comparative example 2>
A negative electrode layer was prepared in the same manner as described in Example 1. The negative electrode layer thus produced was immersed in a container filled with the solid electrolyte precursor solution prepared in the same manner as described in Example 1, and vacuum impregnated at room temperature for 1 hour. Thereafter, the negative electrode layer was sandwiched between the footwear films and lightly squeezed with a roll to remove the excess solid electrolyte precursor solution, thereby obtaining an impregnated negative electrode layer.

  Except for using the impregnated negative electrode layer thus prepared as the negative electrode layer, thermal polymerization was performed in the same manner as in Example 1 to obtain a laminate of the positive electrode layer-separator layer-negative electrode layer. At this time, the electrolyte layer is not contained in the positive electrode layer.

  Thereafter, in the same manner as in the method described in Example 1, a laminated secondary battery was produced.

In the multilayer secondary battery thus obtained, the electrolyte of the positive electrode layer is a liquid material, and the electrolyte of the separator layer and the negative electrode layer is a polymer electrolyte. Further, a liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) is used for the positive electrode layer of the stacked secondary battery, and a conductivity of 6 × is used for the separator layer and the negative electrode layer. A 10 ⁻⁴ (S / cm) gel polymer electrolyte was used.

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Comparative Example 3>
In Comparative Example 2, a laminated secondary battery was produced in the same manner as Comparative Example 2 except that the positive electrode layer and the negative electrode layer used in Example 3 were used.

In the multilayer secondary battery thus obtained, the electrolyte of the positive electrode layer is a liquid material, and the electrolyte of the separator layer and the negative electrode layer is a polymer electrolyte. Further, a liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) is used for the positive electrode layer of the stacked secondary battery, and a conductivity of 6 × is used for the separator layer and the negative electrode layer. A 10 ⁻⁴ (S / cm) gel polymer electrolyte was used.

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Comparative Example 4>
In Comparative Example 2, a laminated secondary battery was produced in the same manner as in Comparative Example 1 except that the positive electrode layer and the negative electrode layer used in Example 5 were used.

In the multilayer secondary battery thus obtained, the electrolyte of the positive electrode layer is a liquid material, and the electrolyte of the separator layer and the negative electrode layer is a polymer electrolyte. Further, a liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) is used for the positive electrode layer of the stacked secondary battery, and a conductivity of 6 × is used for the separator layer and the negative electrode layer. A 10 ⁻⁴ (S / cm) gel polymer electrolyte was used.

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

<Comparative Example 5>
In Comparative Example 2, a battery was produced in the same manner as in Comparative Example 1, except that the positive electrode layer and the negative electrode layer produced in Example 7 were used.

In the multilayer secondary battery thus obtained, the electrolyte of the positive electrode layer is a liquid material, and the electrolyte of the separator layer and the negative electrode layer is a polymer electrolyte. Further, a liquid electrolyte having a conductivity of 2 × 10 ⁻³ (S / cm) is used for the positive electrode layer of the stacked secondary battery, and a conductivity of 6 × is used for the separator layer and the negative electrode layer. A 10 ⁻⁴ (S / cm) gel polymer electrolyte was used.

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

  The secondary battery thus manufactured was tested for charge / discharge characteristics according to the following method, and the results are shown in Table 1 below.

  Examples 1 and 2 and Comparative Examples 1 and 2; Examples 3 and 4 and Comparative Example 3; Examples 5 and 6 and Comparative Example 4; It can be seen that the battery is a battery with excellent discharge efficiency, high capacity and high output.

1 is a schematic cross-sectional view schematically showing an outline of a laminated flat non-bipolar lithium ion secondary battery which is a typical embodiment of a lithium ion battery of the present invention. It is the cross-sectional schematic which represented typically the outline | summary of the laminated flat bipolar lithium ion secondary battery which is another typical embodiment of the lithium ion battery of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view schematically showing an appearance of a stacked flat lithium ion secondary battery that is a typical embodiment of a lithium ion battery according to the present invention. 4A and 4B are external views schematically showing typical embodiments of the assembled battery according to the present invention, in which FIG. 4A is a plan view of the assembled battery, FIG. 4B is a front view of the assembled battery, and FIG. It is a side view of a battery. It is a conceptual diagram of the vehicle carrying the assembled battery of this invention. It is the schematic diagram showing one Embodiment of the electrode layer of the lithium ion battery which concerns on this invention.

Explanation of symbols

10 Non-bipolar lithium ion secondary battery,
11 positive electrode current collector,
11a Outermost layer positive electrode current collector,
12, 32 positive electrode (positive electrode active material layer),
13, 35 electrolyte layer,
14 negative electrode current collector,
15, 33 negative electrode (negative electrode active material layer),
16, 36 single battery layer (= battery unit or single cell),
17, 37, 57 Power generation element (battery element; laminate),
18, 38, 58 positive electrode tab,
19, 39, 59 negative electrode tab,
20, 40 Positive terminal lead,
21, 41 Negative terminal lead,
22, 42, 52 Battery exterior material (for example, laminate film),
30 Bipolar lithium ion secondary battery,
31 current collector,
31a The outermost layer current collector on the positive electrode side,
31b The outermost layer current collector on the negative electrode side,
34 Bipolar electrode,
34a, 34b The electrode located in the outermost layer,
43 Sealing part (insulating layer),
50 lithium ion secondary battery,
250 small battery pack,
300 battery packs,
310 connection jig,
400 electric car,
500 current collector,
510 active material layer,
511 first active material layer,
512 second active material layer,
520 groove,
530 Electrode layer.

Claims (9)

A secondary battery including at least one single battery layer in which a positive electrode layer, a separator layer, and a negative electrode layer are laminated in this order,
Electrolyte conductivity of the negative electrode layer is rather high than the separator layer and the conductivity of the at least one of the electrolyte of the positive electrode layer, the electrolyte of the negative electrode layer is a liquid material, an electrolyte polymer electrolyte of the separator layer, the electrolyte of the positive electrode layer Is a liquid substance or polymer electrolyte,
At least the positive electrode layer and the separator layer are in pressure contact, and the electrolyte present at the interface between the separator layer and the positive electrode layer and the separator layer forms a cross-linked structure, and at least the positive electrode layer and the separator layer are in close contact with each other , Secondary battery. The secondary battery according to claim 1 , wherein the positive electrode layer and the separator layer, and the negative electrode layer and the separator layer are in close contact with each other. In the secondary battery, the negative electrode layer comprises a plurality of layers having different porosities in the thickness direction of the negative electrode layer, the secondary battery according to claim 1 or 2. The positive electrode layer includes a current collector and an active material layer containing a positive electrode active material formed on the current collector, and the current collector is 10% or less of an average particle diameter of the positive electrode active material And / or the negative electrode layer includes a current collector and an active material layer including a negative electrode active material formed on the current collector, and the current collector There has a groove of the negative active average of 10% or less of the width and depth of the particle diameter of material, the secondary battery according to any one of claims 1-3. The positive electrode layer includes a current collector and an active material layer including a positive electrode active material formed on the current collector, the active material layer has a groove, and / or the negative electrode layer includes: The active material layer containing the electrical power collector and the negative electrode active material formed on the said electrical power collector, The said active material layer has a groove | channel of any one of Claims 1-4 . Secondary battery. By applying pressure in the thickness direction of the laminate from the outside to the laminate of the separator layer impregnated with the positive electrode layer and the polymer electrolyte precursor solution and the negative electrode layer not containing the electrolyte, and polymerizing the electrolyte of the separator, A step of bonding the positive electrode layer, the separator layer, and the negative electrode layer to produce a laminate of the positive electrode layer, the separator layer, and the negative electrode layer; and a step of injecting a liquid electrolyte into the laminate after the bonding step I have a,
A method for producing a secondary battery, wherein the conductivity of the electrolyte of the negative electrode layer of the obtained secondary battery is higher than the conductivity of the electrolyte of at least one of the separator layer and the positive electrode layer . By applying pressure in the thickness direction of the laminate from the outside to the laminate of the separator layer impregnated with the positive electrode layer and the polymer electrolyte precursor solution and the negative electrode layer not containing the electrolyte, and polymerizing the electrolyte of the separator layer A step of adhering the positive electrode layer, the separator layer, and the negative electrode layer to produce a laminate of the positive electrode layer, the separator layer, and the negative electrode layer; and after the bonding step, injecting a liquid electrolyte into the laminate, We have a process of vacuum impregnation,
A method for producing a secondary battery, wherein the conductivity of the electrolyte of the negative electrode layer of the obtained secondary battery is higher than the conductivity of the electrolyte of at least one of the separator layer and the positive electrode layer . The manufacturing method according to claim 6 or 7 , wherein, in the liquid injection step, pressurization is performed from a direction perpendicular to the surface of the laminate so that the thickness of the laminate is within 5% of a predetermined thickness. A positive electrode active material, wherein the positive electrode layer is formed on a current collector having a groove having a width and a depth of 10% or less of an average particle diameter of the positive electrode active material, and / or the negative electrode layer is a negative electrode active material The negative electrode layer is formed on a current collector having a groove having a width and a depth of 10% or less of the average particle diameter of the negative electrode active material on the surface of the negative electrode layer.
The method according to any one of claims 6-8.

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