CN1245593A - Manufacture method of lithium ion secondary battery - Google Patents

Abstract

The manufacture of a lithium ion secondary battery which can take optional form such as a thin type, is compact and highly efficient and has stable properties, being composed of a positive electrode, a negative electrode, a separator, and an electrolyte. In this manufacture, a battery laminate, which has layers of laminates each of which is made by laying a positive electrode and a negative electrode severally on a separator after applying the binder resin solution made by dissolving fluoric resin or polyvinyl alcohol in a solvent, to the separator is made, and a plate-shaped battery laminate is made by drying this battery laminate under pressure so as to evaporate the solvent, and then this plate-shaped battery laminate is impregnated with an electrolyte.

Description

Manufacturing method of lithium ion secondary battery

technical field

The present invention relates to a method for manufacturing a lithium ion secondary battery, and more specifically, relates to a method for manufacturing a lithium ion secondary battery that can be thinned and lightened in any shape.

Background technique

In keeping with the downsizing and weight reduction of portable electronic devices, improvement of the electric energy capacity of batteries has become the most important issue, and various batteries have been developed and improved. Among conventional batteries, lithium-ion secondary batteries are the secondary batteries in which high capacity can be expected the most, and improvements are still actively being made. A lithium ion secondary battery has, as its main components, a positive electrode, a negative electrode, and an ion conductive layer sandwiched between the positive electrode and the negative electrode. In lithium-ion secondary batteries that are currently in practical use, the ion-conductive layer is one in which a porous film such as polyethylene or polypropylene is impregnated with a non-aqueous solvent containing lithium ions.

Lithium-ion secondary batteries that are currently in practical use use a strong outer can made of stainless steel or the like, and pressurize to maintain the electrical connection between the positive electrode-ion conductive layer-negative electrode. However, the above-mentioned exterior can increases the weight of the lithium ion secondary battery, making it difficult to reduce the size and weight of the lithium ion secondary battery, and also makes it difficult to form an arbitrary shape due to the rigidity of the exterior can. In order to reduce the size and weight of lithium-ion secondary batteries and to achieve arbitrary shapes, it is necessary to join the positive electrode and the ion-conducting layer, and the negative electrode and the ion-conducting layer, and maintain this state without applying pressure from the outside.

As a method in this regard, in U.S. Patent No. 5,437,692, there is disclosed a method in which a lithium-ion-conductive polymer is used as an ion-conducting layer, and a positive electrode and a negative electrode are bonded to the above-mentioned conductive layer with an adhesive layer containing a lithium compound. method. In addition, WO95/15589 discloses a method of forming a plastic ion-conducting layer first, and then using the plastic ion-conducting layer to join positive and negative electrodes.

However, if the method disclosed in the above-mentioned U.S. Patent No. 5,437,692 is used, sufficient strength cannot be obtained, and the battery cannot be made thin enough. In addition, the ionic conduction resistance between the ion-conducting layer and the positive electrode and the negative electrode is also high, and the charge-discharge Battery characteristics, such as battery characteristics, also have practical problems. In addition, according to the above-mentioned WO95/15589, since the plastic ion-conducting layer is bonded, there is a problem that sufficient strength cannot be obtained, and the battery cannot be made thin enough.

The present invention is made in order to eliminate the above-mentioned problems, and the purpose is to provide a manufacturing method of a lithium-ion secondary battery: use an adhesive resin to make the positive electrode and the negative electrode and the ion-conducting layer (separator) adhere tightly, and the battery can be ensured. Sufficient bonding strength between the electrodes and the separator can be ensured, and the ion conduction resistance between the positive electrode and the negative electrode and the separator can be ensured to be similar to that of a battery using a conventional external can.

disclosure of invention

The manufacturing method of the 1st kind of lithium ion secondary battery of the present invention has the following steps: forming the positive electrode and negative electrode active material layers on the positive electrode and the negative electrode current collector respectively to form the process of each electrode; The process of applying an adhesive resin solution formed by dissolving resin or polyvinyl alcohol into a solvent to a separator; the process of overlapping each of the above-mentioned electrodes alternately between the separators to form a multilayer laminate; the laminate a step of drying the body under pressure to evaporate the solvent to form a flat battery laminate; and a step of impregnating the flat battery laminate with an electrolytic solution.

A second method of manufacturing a lithium ion secondary battery of the present invention is a method of forming a multilayer laminate through cut separators in the above first method of manufacturing a lithium ion secondary battery.

A third method of manufacturing a lithium ion secondary battery of the present invention is a method of forming a multilayer laminate through a wound separator in the above first method of manufacturing a lithium ion secondary battery .

A fourth method of manufacturing a lithium ion secondary battery of the present invention is a method of forming a multilayer laminate through a folded separator in the above first method of manufacturing a lithium ion secondary battery.

Adoption of the manufacturing method of the above-mentioned 1st to 4th lithium ion secondary battery makes it possible to prevent the gap between the separators and the separators composed of the positive electrode and the negative electrode active material and the positive electrode and the negative electrode current collector respectively bonded to the active material. Even if there is no rigid case, the structure of the battery can be maintained, so the battery can be made lighter and thinner, and the charge and discharge can be improved by the adhesive resin solution applied to the separator. characteristics, by adopting a multilayer laminated body, a small and compact lithium ion secondary battery with stable characteristics can be obtained. In addition, when an external force or internal thermal stress acts on the formed battery to deform it, since it is between the active material layer of the electrode and the collector rather than the separator that is destroyed, it also has The effect of safety can be maintained.

The 5th kind of manufacturing method of lithium-ion secondary battery of the present invention is that in the manufacturing method of the above-mentioned 1st kind of lithium-ion secondary battery, the adhesive resin solution uses dimethylformamide as a solvent, and the solvent contains Fluorine resin or polyvinyl alcohol solution method.

The 6th kind of manufacturing method of lithium-ion secondary battery of the present invention is that in the manufacturing method of above-mentioned 5th kind of lithium-ion secondary battery, adhesive resin solution is in dimethylformamide, fluorine-based resin or polyethylene The alcohol contains 3 to 25 parts by weight, preferably 5 to 15 parts by weight of the solution.

A seventh method of manufacturing a lithium ion secondary battery according to the present invention is a method of drying in an air current of 80° C. or lower in the above first method of manufacturing a lithium ion secondary battery. Therefore, the time required for drying can be shortened.

In the eighth method of manufacturing a lithium ion secondary battery of the present invention, in the above first method of manufacturing a lithium ion secondary battery, before applying the adhesive resin solution to the separator, the surface of the separator is Method of plasma treatment. Therefore, adhesiveness can be further improved.

A brief description of the drawings

FIG. 1, FIG. 2 and FIG. 3 are schematic sectional views of main parts of an example of a lithium ion secondary battery obtained by the manufacturing method of the present invention. FIG. 4 is a schematic view schematically showing the configuration of a single laminate shown in FIGS. 1 , 2 , and 3 described above.

preferred embodiment

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The schematic cross-sectional views of the main parts of Fig. 1, Fig. 2 and Fig. 3 show an embodiment of the lithium-ion secondary battery of the present invention, and the schematic diagram of Fig. 4 schematically shows the above-mentioned Fig. The composition of a single laminated body. In each figure, 12 is a laminated body, and the laminated body 12 is composed of the following parts: the positive electrode 1 formed by forming the positive electrode active material layer 3 is formed on the positive electrode current collector 2 made of metal such as aluminum foil, and the positive electrode 1 made of copper The upper side of the negative electrode current collector 5 made of metal such as the negative electrode 4 formed by forming the negative electrode active material 6, keeps the separator 7 containing the electrolyte solution of lithium ions, and makes the separator 7 and the positive electrode 1 and the separator 7 and the negative electrode 4 The adhesive resin layer 8 for bonding. The adhesive resin layer 8 has micropores, and the micropores hold the electrolytic solution.

As the positive electrode current collector 2 or the negative electrode current collector 5, any metal that is stable in the lithium-ion secondary battery can be used. It is desirable to use aluminum as the positive electrode current collector 2, and it is desirable to use aluminum as the negative electrode current collector. copper. The shape of the current collectors 2 and 5, foil, mesh, metal mesh, etc., can be used, but in order to obtain the bonding strength with the active material and to facilitate the impregnation of the electrolyte solution after bonding, a mesh A shape with a large surface area such as a metal mesh or a metal mesh is ideal.

The active material contained in the positive electrode active material layer, for example, can use a composite oxide between lithium and transition metals such as cobalt, manganese, nickel, a composite oxide between lithium and a chalcogenide, or in these composite compounds Composite compounds containing transition metals and composite compounds having various trace elements added to the above-mentioned composite oxides are not particularly limited to these.

The active material contained in the negative electrode active material layer 6 is preferably a carbonaceous material, but in the battery of the present invention, it can be used irrespective of its chemical characteristics, shape, and the like.

Any material used for the separator 7 can be used as long as it is an insulating porous film, net, non-woven fabric, etc. impregnated with an electrolytic solution and can obtain sufficient strength. It is preferable to use a porous membrane made of polypropylene, polyethylene, or the like from the viewpoint of ensuring safety.

As the polymer material for forming the adhesive resin layer 8, for example, a fluorine-based resin or a mixture mainly composed of a fluorine-based resin, polyvinyl alcohol or a mixture mainly composed of polyvinyl alcohol can be used. As the fluorine-based resin, specifically, polymers or copolymers having fluorine atoms in the molecular structure such as vinylidene fluoride and 4-vinyl fluoride, polymers or copolymers having vinyl alcohol in the molecular skeleton, or Mixture with polymethyl methacrylate, polystyrene, polyethylene, polypropylene, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polyethylene oxide, etc. In particular, polyvinylidene fluoride, which is a fluorine-based resin, is suitable.

As the electrolytic solution, ether solvents such as dimethoxyethane, diethoxyethane, dimethyl ether, and diethyl ether, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, etc., can be used. An electrolyte solution in which an electrolyte such as LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiC(CF ₃ SO ₂ ) _{3 ,} etc. is dissolved in a single or a mixture of ester solvents such as .

Next, a method for manufacturing the laminate of the lithium ion secondary battery shown in FIG. 1 will be described.

First, mix an appropriate amount of binder resin (conductive materials such as graphite powder into the active material of the positive electrode 1) in the respective active materials of the positive electrode 1 and the negative electrode 4 and make it into a paste. The active material in the shape of is coated on the positive electrode current collector 2 and the negative electrode current collector 5 respectively, and after drying, each electrode of the positive electrode 1 and the negative electrode 4 is formed. As the adhesive resin used here, besides the resin whose main component is the same as that used for the adhesive resin layer 8 , various resins such as polyethylene can be used.

Next, the above-mentioned adhesive resin solution for coating is uniformly applied to the entire surface of the spacer 7 . The coating can be applied by the pulling method of pulling up with the adhesive resin solution, the rod applicator method of dripping the adhesive resin on the spacer and applying it evenly with a bar applicator, and the spray method on the spacer. Spraying method of applying adhesive resin, etc. In addition, when a fluorine-based resin is used for the spacer, plasma treatment may be performed on the surface to secure adhesiveness.

In the case where the binding resin solution is applied to the electrodes instead of the separator, the binding resin solution will permeate into the electrodes, reducing the bonding strength between the separator and the electrodes. In addition, since the binder resin solution penetrates into the electrodes, the conduction path of lithium ions will be reduced and the battery characteristics will be reduced. In addition, when the binder resin used for electrode formation contains polyvinylidene fluoride or polyvinyl alcohol as a main component, it will be dissolved by the binder resin solution for coating, and the strength of the electrode will be lowered.

By applying the adhesive resin solution to the separator, the infiltration of the adhesive resin solution into the electrode can be prevented, and the dissolution of the adhesive resin for electrode formation caused by the adhesive resin solution can be prevented. The adhesive force between electrodes can be suppressed from decreasing in electrode strength.

Furthermore, the adhesive resin layer properly formed on the interface between the separator and the electrode can improve the utilization efficiency of the active material inside the electrode for doping and dedoping of lithium ions. That is to say, the ease of movement of lithium ions is equal to that in the solution, so the doping and dedoping of lithium ions are concentrated on the active material part adjacent to the separator, although there may be cases where the active material inside the electrode cannot be effectively used problem, but with the help of the adhesive resin solution applied to the separator to cover the surface of the active material near the separator, the active part becomes less than the active material inside the electrode, so that the active material near the separator and the active material inside the electrode The doping and dedoping speed of the active material is uniform, thereby improving the charge and discharge efficiency.

The adhesive resin solution usually uses an N-methylpyrrolidone solution mainly composed of 3 to 25 parts by weight, preferably 5 to 15 parts by weight, of polyvinylidene fluoride or polyvinyl alcohol. If the adhesive resin is too thin, enough resin cannot be applied and the adhesive strength will be insufficient. If the solution is too thick, the amount of applied resin will be too much. As a result, the ionic conductivity between the electrodes will decrease, resulting in Less than good battery characteristics.

Next, before the adhesive resin solution dries, one of the above-mentioned electrodes is superimposed between the separators coated with the adhesive resin, heated and dried by applying pressure from both sides with a pressure roller, etc., and then cut into a predetermined shape. Size, on the outside of the spacer sandwiching the electrode of one side, superimpose the electrode of the other side that has been coated with adhesive resin and cut into a specified size, and then superimpose the electrode that has been coated with adhesive resin on the outside. The electrodes on the other side are sandwiched between the separators. The above steps were repeated to produce a multilayer battery laminate, and the multilayer battery laminate was dried under pressure to form a flat battery laminate. The heating temperature at this time is preferably 60 to 100°C. At a temperature lower than 60°C, it takes a long time to dry, which is not preferable from an engineering point of view. At a temperature higher than 100° C., there is a possibility of adversely affecting spacers and the like, which is not preferable. Then, heating may be continued in order to remove residual solvent, but in this case, no special pressure is required. The practice of reducing the pressure during heating is effective in shortening the drying time, but it is not a necessary condition.

The flat battery laminate having the multi-layered laminate of the positive electrode 1 and the negative electrode 4 formed as described above bonded to the separator 7 was inserted into an aluminum laminated film bag, and the above-mentioned battery laminate was immersed in a reduced pressure state. The electrolyte solution is heat-sealed in an aluminum laminated film bag to complete a lithium-ion secondary battery.

As described above, since it is possible to prevent separation between the separators and the separators, which are composed of the positive electrode and negative electrode active materials and the positive electrode and negative electrode current collectors respectively bonded to the active materials, even if there is no rigid case, the The structure as a battery can be maintained, so the battery can be made lighter and thinner, and the charging and discharging characteristics can be improved by means of the adhesive resin solution applied to the separator, and a laminate with multiple layers can be used. A small and compact lithium ion secondary battery with stable characteristics can be obtained. In addition, when an external force or internal thermal stress acts on the formed battery to deform it, since it is between the active material layer of the electrode and the collector rather than the separator that is destroyed, it also has The effect of safety can be maintained.

In addition, as a solvent for the adhesive resin solution, use a solvent with a boiling point lower than that of N-methylpyrrolidone (boiling point 201°C), which can dissolve fluorine-based resins such as polyvinylidene fluoride or adhesives with polyvinyl alcohol as the main component. The dimethylformamide method of the resin can shorten the time of the solvent evaporation process. The binder resin mainly composed of polyvinylidene fluoride or polyvinyl alcohol in dimethylformamide is 3 to 25 parts by weight, preferably 5 to 15 parts by weight.

In addition, the time required for drying can be shortened by exposing each electrode to the separator coated with the adhesive resin solution and exposing it to an air flow below 80°C.

Hereinafter, the present invention will be further described in detail by giving examples including the examples shown in FIG. 2 and FIG. 3 .

Example 1

(production of positive electrode)

The positive active material paste prepared by dispersing 87 parts by weight of LiCoO ₂ , 8 parts by weight of graphite powder, and 5 parts by weight of polyvinylidene fluoride into N-methylpyrrolidone (hereinafter referred to as NMP) was used with a scraper blade ( Doctor Blade) coating thickness of about 300 microns to form a positive electrode active material film. An aluminum mesh with a thickness of 30 micrometers to be the positive electrode current collector 2 was placed on the top thereof, and a positive electrode active material paste adjusted to a thickness of 300 micrometers was applied again on the top thereof by the doctor blade method. After being left in a dryer at 60° C. for 60 minutes, it became semi-dry to form a laminate of the positive electrode current collector 2 and the positive electrode active material. The positive electrode 1 in which the positive electrode active material layer 3 was formed was produced by rolling the laminated body to a thickness of 400 μm. After immersing the positive electrode 1 in the electrolytic solution, the peel strength between the positive electrode active material layer and the positive electrode current collector was measured, and the value of the strength was 20 to 25 gf/cm.

(production of negative electrode)

Disperse 95 parts by weight of メソフェ-ズマィクロビ-ズカ-bon (Osaka Gas production) and 5 parts by weight of polyvinylidene fluoride into NMP to prepare the negative electrode active material paste, and apply it to a thickness of 300 microns with a doctor blade method , forming a negative electrode active material film. A copper mesh with a thickness of 20 micrometers to be a negative electrode current collector was placed on the upper part, and a negative electrode active material paste adjusted to a thickness of 300 micrometers was coated on the upper part again by the doctor blade method.

After being left in a dryer at 60° C. for 60 minutes, it became semi-dry to form a laminate of the negative electrode current collector 5 and the negative electrode active material. The negative electrode 4 in which the negative electrode active material layer 6 was formed was produced by rolling the laminated body to a thickness of 400 μm.

After the negative electrode 4 was soaked in the electrolytic solution, the peel strength between the negative electrode active material layer 6 and the negative electrode current collector 5 was measured, and the value of the strength was 5 to 10 gf/cm.

(production of batteries)

5 parts by weight of polyvinylidene fluoride and 95 parts by weight of NMP were mixed and sufficiently stirred to form a uniform solution to prepare an adhesive resin solution.

Next, the above-mentioned adhesive resin was dripped on each of one surface of two continuous rectangular strip-shaped porous polypropylene sheets (manufactured by ヘキスト, trade name: Selga-do #2400) used as the spacer 7. , On the spacer, move the rod applicator that finely winds the filament with a diameter of 0.5 mm on the glass tube with a diameter of 1 cm, and apply the adhesive resin solution evenly to the entire surface of the spacer.

Next, before the adhesive resin is dried, the positive electrode 1 as one electrode is closely pasted to the coated surface of the above-mentioned polypropylene sheet, and after being heated and dried with a pressure roller or the like from both sides, it is cut into a predetermined size, and then , with a rod applicator on the uncoated surface of the cut polypropylene sheet, the same adhesive resin solution is applied, and the negative electrode 4 that has been cut into a predetermined size as the other electrode is superimposed on the coated surface. Then use a rod applicator to apply an adhesive resin solution to the uncoated surface of the polypropylene sheet sandwiching the above-mentioned cut positive electrode, and make the coated surface overlap the above-mentioned negative electrode. . This fixation is repeated to form a multilayer laminate. The multi-layer laminate was heated in a drier at 60° C. in the airless state while being pressurized, and NMP as a solvent was evaporated to form a flat battery laminate as shown in FIG. 1 . By evaporating NMP, the adhesive resin becomes a porous film with continuous pores.

Next, insert the flat battery laminate formed into a predetermined size into an aluminum laminated film bag, and immerse it in ethylene carbonate (manufactured by Kanto Chemical Co., Ltd.) at a concentration of 1.0 mol/ ^dm3 under reduced pressure. An electrolyte solution in which LiPF ₆ (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in a mixed solvent (1:1 molar ratio) with dimethyl carbonate (manufactured by Wako Pure Chemical Industries, Ltd.). Afterwards, heat sealing is used for sealing treatment to produce a lithium ion secondary battery having the battery laminate shown in FIG. 1 .

Example 2

Only the adhesive resin solution of the above-mentioned Example 1 was changed as follows, and the same treatment as in Example 1 was carried out to produce a lithium ion secondary battery having the battery laminate shown in FIG. 1 .

5 parts by weight of polyvinyl alcohol and 95 parts by weight of NMP were mixed and sufficiently stirred to form a uniform solution to prepare an adhesive resin solution.

Example 3

The NMP used as the solvent of the adhesive resin solution in the above-mentioned Examples 1 and 2 was replaced with dimethylformamide, and the others were treated in the same manner as in Example 1 to obtain a lithium battery with the battery laminate shown in Figure 1. ion secondary battery. In this case, the step of evaporating the solvent can be shortened compared to Example 1.

Example 4

Using dimethylformamide instead of NMP as the solvent of the adhesive resin solution in the above-mentioned Examples 1 and 2, and exposing the process of evaporating the solvent to an air stream at 60°C, it is the same as in Example 1 except that By performing the same treatment, a lithium ion secondary battery having the battery laminate shown in FIG. 1 was obtained.

In this case, the process of evaporating the solvent can be shortened compared with Examples 1, 2 and 3.

The glass strength of the lithium ion secondary batteries obtained in Examples 1 to 4 above was measured. The peel strengths of positive electrode 1 and separator 7, negative electrode 4 and separator 7 were 23 gf/cm and 12 gf/cm, respectively, exceeding the adhesion between active material layers 3, 6 and current collectors 2, 5 in each electrode strength.

Example 5

In the above-mentioned Example 1, a flat battery laminate having a multilayer laminate was formed through a plurality of cut separators. In the present example, a plate-shaped battery laminate having a multilayer laminate is formed through a wound separator, and the same process as in Example 1 is performed except that the battery having the battery shown in FIG. 2 is obtained. Lithium-ion secondary battery of the battery stack.

(production of batteries)

Coating the adhesive resin solution on each single side of each of two strip-shaped separators 7 made of a porous polypropylene sheet (produced by ヘキスト, trade name セヘキスト, trade name セヘキスト) 4 (or the positive electrode) is sandwiched between the coated surfaces and pasted closely, and then dried by heating while pressing.

On one side of the strip-shaped separator 7 that sandwiches the negative electrode 4 (or positive electrode) and bonded in the middle, an adhesive resin solution is applied, and one end of the separator 7 is bent by a predetermined amount, and the positive electrode 1 ( Or negative electrode) sandwiched in the middle of the crease and overlapped to pass into the laminator. Next, apply an adhesive resin solution to the other side of the above-mentioned strip-shaped separator, and paste another positive electrode 1 (or negative electrode) at a position opposite to the positive electrode 1 (or negative electrode) sandwiched at the crease. ), the separator is rolled into an oblong shape, and the process of winding the separator while pasting another positive electrode 1 (or negative electrode) is repeated to form a multi-layer laminate, and the battery body is dried while being pressed to produce A flat battery laminate as shown in FIG. 2 was obtained.

In this embodiment, although the example of winding the separator 7 is shown, it is also possible to fold the separator in which the strip-shaped negative electrode 4 (or positive electrode 1) has been joined between the separators 7, and repeat it while folding. The process of folding the separator while affixing the positive electrode 1 (or negative electrode).

Example 6

Only the strip-shaped separator, the positive electrode and the negative electrode are wound at the same time, which is different from the above-mentioned Example 5, and the rest are processed in the same way as in Examples 1 and 5 to produce a flat battery laminate as shown in Figure 3. Lithium-ion secondary battery.

(production of batteries)

The strip-shaped negative electrode 4 (or positive electrode) is disposed between two strip-shaped separators 7 made of a porous polypropylene sheet (produced by ヘキスト, trade name セヘキスト, trade name #2400), and made to protrude by a certain amount. A strip-shaped positive electrode 1 (or negative electrode) is arranged outside one separator 7 . On the surface of the inside of each spacer 7 and the outer surface of the configuration positive pole 1 (or negative pole) spacer 7, apply adhesive resin, make positive pole 1 (or negative pole) and 2 pieces of spacer 7 and negative pole 4 (or positive pole) ) into the laminator, and then, on the outer surface of the other side of the spacer 7, the adhesive resin is coated, and the protruding positive electrode 1 (or negative electrode) is bent and pasted on the coated surface , the laminated laminate is wound into a long circle, so that the bent positive electrode 1 (or negative electrode) is wrapped inside to form a multi-layer laminate, and the battery body is dried while heating to obtain A flat battery laminate.

The characteristics of the lithium-ion secondary batteries obtained in Examples 1 to 6 were evaluated, and it was found that the gravimetric energy density was 100Wh/kg, and even after 200 charge-discharge cycles with a current value C/2, the charge capacity 75% of the initial level can still be maintained.

Possibility of industrial use

A secondary battery that can be used as a portable electronic device such as a portable personal computer and a handy phone can realize miniaturization, weight reduction, and arbitrary shape while improving the performance of the battery.

Claims (8)

1. A manufacturing method for a lithium ion secondary battery, characterized in that: possess the following steps: forming a positive electrode and a negative electrode active material layer on a positive electrode and a negative electrode current collector respectively to form each electrode; The process of applying an adhesive resin solution formed by dissolving fluorine-based resin or polyvinyl alcohol in a solvent to the separator; the process of overlapping the above-mentioned electrodes alternately between the separators to form a multi-layer laminate; a step of drying the laminate under pressure to evaporate the solvent to form a flat battery laminate; and a step of impregnating the flat battery laminate with an electrolytic solution. 2. The method for manufacturing a lithium ion secondary battery according to claim 1, wherein a multilayer laminate is formed through the cut separator. 3. The method for manufacturing a lithium ion secondary battery according to claim 1, wherein a multilayer laminate is formed through a wound separator. 4. The method for manufacturing a lithium ion secondary battery according to claim 1, wherein a multilayer laminate is formed through the folded separator. 5. The manufacturing method of a lithium ion secondary battery according to claim 1, wherein the adhesive resin solution is a solution containing dimethylformamide as a solvent, and the solvent contains a fluorine-based resin or polyvinyl alcohol. 6. The manufacturing method of lithium-ion secondary battery according to claim 5, characterized in that: the bonding resin solution is in dimethylformamide, and fluorine resin or polyvinyl alcohol contains 3 to 25 parts by weight, ideally It is a solution containing 5 to 15 parts by weight. 7. The manufacturing method of the lithium ion secondary battery as claimed in claim 1, characterized in that: the drying is carried out in an air flow below 80°C. 8. The method for manufacturing a lithium ion secondary battery as claimed in claim 1, wherein the surface of the separator is subjected to plasma treatment before the adhesive resin solution is applied to the separator.

Images