JP6531491B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery in which a battery element is accommodated in a film outer package, and in particular, even when gas is generated, the gas can be reliably discharged from a predetermined position, and a deformation of the battery element The present invention relates to a secondary battery provided with a safety mechanism capable of preventing the

  In recent years, there has been a strong demand for downsizing and weight reduction in batteries used as power sources for electronic devices and automobiles, and many of the battery exterior bodies use laminate films instead of conventional metal cans. It has become to. As the laminate film, a film using aluminum as the metal thin film, nylon (registered trademark) or polyethylene terephthalate on the outer surface of the battery as the heat fusible resin film, and polyethylene or polypropylene on the inner surface is generally used. A film-clad battery is a battery in which a battery element is housed together with an electrolyte in an outer package (also referred to as a "film package") made of such a laminate film.

  On the other hand, in the secondary battery, the electrolytic solution is electrolyzed or thermally decomposed under an overcharge or high temperature to generate a gas inside, which may increase the internal pressure of the outer package. Conventionally, various safety devices have been proposed in order to ensure the safety of the secondary battery. For example, it is known in the prior art to provide a weak seal portion which breaks preferentially in the seal portion of the film sheath and which functions as a safety valve.

Further, Patent Document 1 discloses a battery in which a needle-like member is provided on the inner surface of an exterior film. According to this battery, when the outer package expands more than a predetermined amount at the time of gas generation, the film is pierced by the needle-like member, and the gas inside can be discharged to the outside from the hole.
There is a risk of

JP 2010-238482

  In the secondary battery, as described above, it is preferable from the viewpoint of safety that the gas can be discharged even if a large amount of gas is generated due to some abnormality. However, in any of the configuration in which the weak seal portion is provided and the configuration in which perforation is performed by the needle-like member, the safety mechanism basically functions after the film case has significantly expanded and deformed. . Therefore, the laminate (battery element) may be deformed due to the deformation of the film casing before the gas is released, and a short circuit may occur.

  The present invention has been made in view of the above problems, and the object thereof is that even if gas is generated, the gas can be reliably discharged from a predetermined position, and An object of the present invention is to provide a secondary battery provided with a safety mechanism capable of preventing deformation of a battery element.

A battery according to one aspect of the present invention for achieving the above object is as follows:
A battery element comprising a positive electrode, a negative electrode, and a separator;
A film case for housing the battery element;
A reinforcing member formed in a cutting portion capable of piercing the film outer package in contact with the film outer package and directly or indirectly fixed to the battery element;
A secondary battery comprising the

(Explanation of terms)
"Indirectly fixed" means that one member is fixed to the other member with some intermediate member interposed.
"Film-clad battery" means a battery in which a battery element is accommodated in a film package together with an electrolyte, and generally has a flat shape as a whole. For example, a battery for an electric vehicle is required to have a large capacity, a low internal resistance, a high heat dissipation and the like, and the film-clad battery is advantageous in these respects.
-"Film exterior body" means an exterior body which is made of a flexible film and contains a battery element, and seals the battery element by arranging two films facing each other and fusing them together. The battery element may be sealed by folding one film and fusing the facing surfaces.

  According to the present invention, even when a gas is generated, the gas can be reliably discharged from a predetermined position, and a safety mechanism capable of preventing deformation of a battery element can be provided.

It is a perspective view which shows the basic structure of a film-clad battery. It is a disassembled perspective view which shows the basic structure of a film-clad battery. It is sectional drawing which shows typically the cross section of the battery of FIG. It is a top view which shows typically the structure of the film-clad battery which concerns on one form of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically the structure of the film-clad battery which concerns on one form of this invention. It is sectional drawing which shows typically the state expanded by gas generation. It is a figure which shows the example of a cutting part. It is sectional drawing of the film-clad battery concerning 2nd Embodiment. It is a top view of the film-clad battery which concerns on another form. It is a top view of the film-clad battery which concerns on another form. It is a top view of the film-clad battery which concerns on another form. It is a top view of the film-clad battery which concerns on another form.

1. Basic configuration of film-clad battery The basic configuration of the film-clad battery will be described with reference to FIGS. 1 to 3. As will be described later, the battery according to one aspect of the present invention is characterized in that a reinforcing member having a cut portion is disposed in the film case. However, for convenience of explanation, those illustrations are omitted in FIGS. 1 to 3. Although the following description will be made by taking a film-type battery with stacked battery elements as an example, the present invention itself is not necessarily limited to the stacked-type battery but may be applied to wound-type batteries and the like.

  The film-clad battery 1 according to an embodiment of the present invention includes a battery element 20, a film case 10 for housing the battery element 20 together with an electrolyte, a positive electrode tab 51 and a negative electrode tab 52 (hereinafter referred to simply as "electrode tabs"). Say)).

  The battery element 20 is formed by alternately laminating a plurality of positive electrodes 30 and a plurality of negative electrodes 40 with the separator 25 interposed therebetween. In the positive electrode 30, the electrode material 32 is applied to both surfaces of the metal foil 31, and similarly, the electrode material 42 is applied to both surfaces of the metal foil 41 in the negative electrode 40. The entire outer shape of the battery element 20 is not particularly limited, but in this example, it is a flat substantially rectangular parallelepiped.

  Each of the positive electrode 30 and the negative electrode 40 has a partially protruding extension in a part of the outer periphery. The extension part of the positive electrode 30 and the extension part of the negative electrode 40 are alternately arranged at shifted positions so as not to interfere with each other when the positive electrode and the negative electrode are stacked. The extensions of all the negative electrodes are collected into one and connected with the negative electrode tab 52, and similarly, with regard to the positive electrodes, the extensions of all the positive electrodes are collected into one and connected with the positive electrode tab 51 ( 2 and 3). A portion collected into one in the stacking direction of the extension portions in this manner is also called a "current collecting portion" or the like. The connection between the current collection portion and the electrode tab may be resistance welding, ultrasonic welding, laser welding, caulking, adhesion with a conductive adhesive, or the like.

  Although various materials can be adopted as the electrode tab, as an example, the positive electrode tab 51 is made of aluminum or an aluminum alloy, and the negative electrode tab 52 is made of copper or nickel. When the material of the negative electrode tab 52 is copper, nickel may be disposed on the surface. Each electrode tab 51, 52 is electrically connected to the battery element 20 and is drawn out of the film case 10.

2. Specifically, the following may be employed for each component of the battery element.

<Separator>
As the separator, for example, polyolefin resins such as aramid, polyimide, polyester, cellulose, polyethylene and polypropylene can be used. A polyolefin resin may be crosslinked by electron beam irradiation or addition of a crosslinking agent to increase the melting point. In addition, any structure such as a woven fabric, a non-woven fabric, or a microporous membrane may be used.

As the separator, a separator made of an inorganic material such as ceramic or glass can also be used. As an inorganic separator, the nonwoven fabric separator which consists of ceramic short fibers, such as an alumina, an alumina silica, and potassium titanate, can be used. Alternatively, it may be a separator comprising a substrate comprising a woven fabric, a non-woven fabric, a paper or a porous film and a layer comprising a heat resistant nitrogen-containing aromatic polymer and a ceramic powder. Alternatively, a heat-resistant layer is provided on part of the surface, and this heat-resistant layer is formed of a porous thin film layer containing ceramic powder, a porous thin film layer of heat resistant resin, or a composite of ceramic powder and heat resistant resin. It may be a porous thin film layer separator. Alternatively, it may be a separator provided with a porous membrane layer in which secondary particles obtained by sintering or dissolving / recrystallizing a part of primary particles of ceramic material are bound by a binder. Or a porous film formed by bonding a ceramic substance and a binder, and as the ceramic substance, silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ) ₂ ) A separator using a nitride of silicon (Si), a hydroxide of aluminum (Al), an alkoxide of zirconium (Zr), or a ketone compound of titanium (Ti). Alternatively, a separator comprising a polymer base and a ceramic-containing coating layer of Al ₂ O ₃ , MgO, TiO ₂ , Al (OH) ₃ , Mg (OH) ₂ , Ti (OH) ₄ formed on the polymer base Or the like.

<Negative electrode>
The negative electrode has a negative electrode current collector made of metal foil and a negative electrode active material layer coated on both sides of the negative electrode current collector. The negative electrode active material layer is bonded by a negative electrode binder so as to cover the negative electrode current collector. The negative electrode current collector is formed to have an extension connected to the negative electrode terminal, and the negative electrode active material is not coated on the extension.

  The negative electrode active material in the present embodiment is not particularly limited. For example, a carbon material capable of absorbing and desorbing lithium ions, a metal capable of alloying with lithium, and a metal oxide capable of absorbing and desorbing lithium ions Can be mentioned.

  As a carbon material, carbon, amorphous carbon, diamond-like carbon, a carbon nanotube, or these composites etc. are mentioned, for example. Here, carbon having high crystallinity has high electrical conductivity, and is excellent in adhesion to a negative electrode current collector made of a metal such as copper and voltage flatness. On the other hand, amorphous carbon having low crystallinity has a relatively small volume expansion, so the effect of alleviating the volume expansion of the entire negative electrode is high, and deterioration due to nonuniformity such as grain boundaries and defects hardly occurs.

  A negative electrode containing a metal or metal oxide is preferable in that it can improve energy density and increase the capacity per unit weight or unit volume of the battery.

  Examples of the metal include Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, an alloy of two or more of these, and the like. Moreover, you may use these metals or alloys in mixture of 2 or more types. Also, these metals or alloys may contain one or more nonmetallic elements.

  Examples of the metal oxide include silicon oxide, aluminum oxide, tin oxide, indium oxide, zinc oxide, lithium oxide, or a composite thereof. In the present embodiment, it is preferable to include tin oxide or silicon oxide as the negative electrode active material, and it is more preferable to include silicon oxide. This is because silicon oxide is relatively stable and hardly causes reaction with other compounds. In addition, one or two or more elements selected from nitrogen, boron and sulfur can be added to the metal oxide, for example, 0.1 to 5% by mass. By this, the electrical conductivity of the metal oxide can be improved.

  In addition, as the negative electrode active material, a plurality of materials can be mixed and used without using a single material. For example, like graphite and amorphous carbon, materials of the same type may be mixed, or as graphite and silicon, different materials may be mixed.

  The binder for the negative electrode is not particularly limited, and examples thereof include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and styrene-butadiene copolymer. Rubber, polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamide imide, polyacrylic acid and the like can be used. Among them, polyimide or polyamideimide is preferable because of its strong binding property. The amount of the binder for the negative electrode to be used is 0.5 to 25 parts by mass with respect to 100 parts by mass of the negative electrode active material from the viewpoint of "sufficient binding ability" and "high energy" in a trade-off relationship. Is preferred.

  As the negative electrode current collector, aluminum, nickel, stainless steel, chromium, copper, silver, and their alloys are preferable from the viewpoint of electrochemical stability. As the shape, foil, flat form, mesh form is mentioned.

<Positive electrode>
The positive electrode has a positive electrode current collector 32 formed of a metal foil, and a positive electrode active material coated on both sides of the positive electrode current collector. The positive electrode active material is bound by the positive electrode binder so as to cover the positive electrode current collector. The positive electrode current collector is formed to have an extension connected to the positive electrode terminal, and the positive electrode active material is not coated on the extension.

The positive electrode active material is not particularly limited as long as it is a material capable of absorbing and desorbing lithium, but from the viewpoint of high energy density, it is preferable to contain a high capacity compound. Examples of high-capacity compounds include lithium nickel composite oxide in which a part of nickel lithiumate (LiNiO ₂ ) or nickel lithiumate is substituted with another metal element, and a layer represented by the following formula (A) Lithium nickel composite oxide is preferred.

Li _y Ni _(1-x) M _x O ₂ (A)
(However, 0 ≦ x <1, 0 <y ≦ 1.2, M is at least one element selected from the group consisting of Co, Al, Mn, Fe, Ti and B.)

From the viewpoint of high capacity, the content of Ni is high, that is, in the formula (A), x is preferably less than 0.5, and more preferably 0.4 or less. As such a compound, for example, Li _α Ni _β Co _γ Mn _δ O ₂ (0 <α ≦ 1.2, β + γ + δ = 1, β ≧ 0.7, γ ≦ 0.2), Li _α Ni _β Co _γ Al _δ O ₂ (0 <α ≦ 1.2, β + γ + δ = 1, β ≧ 0.7, γ ≦ 0.2), etc., and in particular, LiNi _β Co _γ Mn _δ O ₂ (0.75 ≦ β ≦ 0.85, 0.05 ≦ γ ≦ 0.15, 0.10 ≦ δ ≦ 0.20). More specifically, for _{example, LiNi 0.8 Co 0.05 Mn 0.15 O} 2, LiNi 0.8 Co 0.1 Mn 0.1 O 2, LiNi 0.8 Co 0.15 Al 0.05 O ₂ , LiNi _0.8 Co _0.1 Al _0.1 O _{2 and the} like can be preferably used.

From the viewpoint of thermal stability, it is also preferable that the content of Ni does not exceed 0.5, that is, x in the formula (A) is 0.5 or more. It is also preferred that the specific transition metals do not exceed half. Such compounds _{include, Li α Ni β Co γ Mn} δ O 2 (0 <α ≦ 1.2, β + γ + δ = 1,0.2 ≦ β ≦ 0.5,0.1 ≦ γ ≦ 0.4, 0.1 ≦ δ ≦ 0.4). More specifically, LiNi _0.4 Co _0.3 Mn _0.3 O ₂ (abbreviated as NCM 433), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ (abbreviated as NCM523), LiNi _0.5 Co _0.3 Mn _0.2 O ₂ (abbreviated as NCM 532), etc. (however, the content of each transition metal in these compounds fluctuates by about 10%) Can also be mentioned.

  In addition, two or more of the compounds represented by the formula (A) may be mixed and used, for example, NCM532 or NCM523 and NCM433 in the range of 9: 1 to 1: 9 (as a typical example, 2 It is also preferable to use it by mixing in: 1). Furthermore, in the formula (A), a material having a high content of Ni (x is 0.4 or less) and a material having a content of Ni not exceeding 0.5 (x is 0.5 or more, for example, NCM 433) are mixed By doing this, it is possible to construct a battery with high capacity and high thermal stability.

In addition to the above, as a positive electrode active material, for example, LiMnO ₂ , Li _x Mn ₂ O ₄ (0 <x <2), Li ₂ MnO ₃ , Li _x Mn _1.5 Ni _0.5 O ₄ (0 <x < 2) Lithium manganate having a layered structure or spinel structure such as LiCoO ₂ or a part of these transition metals replaced with another metal; Li in these lithium transition metal oxides is more than stoichiometric composition And those having an olivine structure such as LiFePO ₄ . Furthermore, materials in which these metal oxides are partially substituted by Al, Fe, P, Ti, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, etc. Can also be used. Each of the positive electrode active materials described above can be used singly or in combination of two or more.

  Moreover, it is also possible to use a radical material etc. as a positive electrode active material.

  As the binder for the positive electrode, the same one as the binder for the negative electrode can be used. The amount of the positive electrode binder to be used is 0.5 to 15 parts by mass with respect to 100 parts by mass of the positive electrode active material from the viewpoint of "sufficient binding power" and "high energy" which are in a trade-off relationship. Is preferred.

  As the positive electrode current collector, the same one as the negative electrode current collector can be used.

  A conductive auxiliary material may be added to the coating layer of the positive electrode active material for the purpose of reducing the impedance. Examples of the conductive auxiliary include carbonaceous fine particles such as graphite, carbon black and acetylene black.

<Electrolyte>
As the electrolyte, a non-aqueous electrolytic solution containing a lithium salt (supporting salt) and a non-aqueous solvent capable of dissolving the supporting salt can be used.

  As the non-aqueous solvent, non-protic organic solvents such as carbonates (chain or cyclic carbonates), carboxylic acid esters (chain or cyclic carboxylic acid esters), phosphoric acid esters and the like can be used.

  As a carbonate solvent, cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), vinylene carbonate (VC), etc .; dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), linear carbonates such as dipropyl carbonate (DPC); and propylene carbonate derivatives.

  Examples of carboxylic acid ester solvents include aliphatic carboxylic acid esters such as methyl formate, methyl acetate and ethyl propionate; and lactones such as γ-butyrolactone.

  Among these, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (MEC), dipropyl carbonate Carbonates (cyclic or linear carbonates) such as (DPC) are preferred.

  Examples of phosphoric acid esters include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, trioctyl phosphate, triphenyl phosphate and the like.

  In addition, examples of the solvent that can be contained in the non-aqueous electrolytic solution include ethylene sulfite (ES), propane sultone (PS), butane sultone (BS), Dioxathiolane-2, 2-dioxide (DD), sulfolene, and the like. 3-Methylsulfolene, sulfolane (SL), succinic anhydride (SUCAH), propionic anhydride, acetic anhydride, acetic anhydride, maleic anhydride, diallyl carbonate (DAC), dimethyl 2,5-dioxahexanenoate 2,5- Dioxadienohexanoate dimethyl, furan, 2,5-dimethylfuran, diphenyldisulfide (DPS), dimethoxyethane (DME), dimethoxymethane (DMM), diethoxyethane (DEE), ethoxymethoxyethane, chloroethylene carbonate, Dimethyl ether, methyl ether Ether, methyl propyl ether, ethyl propyl ether, dipropyl ether, methyl butyl ether, diethyl ether, phenyl methyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), tetrahydropyran (THP), 1,4-dioxane (DIOX), 1,3-dioxolane (DOL), methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methyl difluoroacetate, methyl propionate, ethyl propionate, propyl propionate, methyl formate Ethylformate, Ethylbutyrate, Isopropylbutyrate, Methylisobutyrate, Methylcyanoacetate, Vinyl Acetate, Dipheny Disulfide, dimethyl sulfide, diethyl sulfide, adiponitrile, valeronitrile, glutaronitrile, malononitrile, succinonitrile, pimeronitrile, suberonitrile, isobutyronitrile, biphenyl, thiophene, methyl ethyl ketone, fluorobenzene, hexafluorobenzene, carbonate electrolyte, glyme Ether, acetonitrile, propiononitrile, γ-butyrolactone, γ-valerolactone, dimethyl sulfoxide (DMSO) ionic liquid, phosphazene, aliphatic formate such as methyl formate, methyl acetate, ethyl propionate, or compounds thereof Some of the hydrogen atoms of are substituted by fluorine atoms.

As a supporting salt, LiPF ₆ , LiAsF ₆ , LiAlCl ₄ , LiClO ₄ , LiBF ₄ , LiBf ₄ , LiSbF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO _{2) 2} ) Lithium salts usable for conventional lithium ion batteries such as ₂ can be used. The supporting salts can be used alone or in combination of two or more.

  The non-aqueous solvents can be used alone or in combination of two or more.

<Film exterior body>
As a film of an exterior body, the laminate film which has a surface layer, a metal layer, and an inner surface layer can be used. Aluminum may be used as the metal layer, nylon (registered trademark) or polyethylene terephthalate may be used as the surface layer, and a polyolefin resin such as polyethylene or polypropylene may be used as the inner surface layer. The inner surface layer may be polyethylene having a melting point of 95 to 140 ° C. or polypropylene having a melting point of 160 to 165 ° C.

  In the present embodiment, as shown in FIG. 1 to FIG. 3, the film case 10 may be configured by opposingly arranging two films 10-1 and 10-2. Although not shown, one film may be folded to constitute a film outer package. The outline shape of the film case 10 is not particularly limited, but may be square, and in this example, it is specifically rectangular.

  The films 10-1 and 10-2 are heat-sealed and bonded to each other around the battery element 20, and the peripheral portion of the film sheath 10 is a heat-sealed portion 15. The heat sealing portion 15 is formed over the entire circumference of the battery.

  In this example, the positive electrode tab 51 and the negative electrode tab 52 are drawn out from one side of the heat sealing part 15 on the short side. Of course, the electrode tabs may be respectively drawn from two or more different sides. It is preferable in one form that the positive electrode tab 51 and the negative electrode tab 52 are parallel, but the present invention is not limited thereto. Further, as shown in FIG. 2 and FIG. 3, the cup portion may be formed on one film 10-1 and the cup portion may not be formed on the other film 10-2. Alternatively, the configuration may be such that the cup portion is formed on both films (not shown), or both may not be configured to form the cup portion (not illustrated).

<Reinforcement member>
As shown in FIGS. 4A and 4B, the film-clad battery 1 of the present embodiment has a reinforcing member 65 disposed inside the film case 10. The reinforcing member may be in various forms, and another example will be described later with reference to the other drawings, but first, the aspect in FIGS. 4A and 4B will be described. In addition, below, the code | symbol of each part may be abbreviate | omitted and described.

  The reinforcing member 65 is a plate-like member in one example. In this example, the reinforcing members 65 are arranged in the width direction of the battery element 20. The reinforcing member 65 is formed to be longer than the width of the battery element 20, and both ends thereof project outward beyond the battery element 20. Cutting sections 66a and 66b are formed at each end. The cutting portion may be a mountain-shaped cutting blade constituted of two inclined sides as shown in FIG. 5 (a), or a cutting constituted of a straight side and an inclined side as shown in FIG. 5 (b) It may be a blade. The shape of the cutting portion may be any shape as long as it can puncture the outer packaging film, and may be formed as protrusions of various shapes.

  A metal material, a ceramic material, or a resin material can be used as the material of the reinforcing member. When the reinforcing member is in contact with the negative electrode which is the outermost layer of the battery element, the metal material used as the reinforcing member is preferably stainless steel which does not ionize at the negative electrode potential, copper, titanium, nickel or the like. Moreover, it is also preferable to comprise the reinforcement member using a metal material as an insulating thing with respect to electrolyte solution, for example, it is good also as what covered the metal material with the insulating material.

  The reinforcing member also serves as a member that prevents deformation of the battery element. Therefore, it is preferable to have sufficient rigidity. In the case of a plate-like reinforcing member, the thickness thereof is preferably, for example, 0.1 mm or more and less than 2.0 mm, and more preferably 0.2 mm or more and less than 1.0 mm. The reinforcing member may not have a plate shape, and may have an uneven cross-sectional shape.

  The length of the reinforcing member is preferably longer than one side of the battery element so that the reinforcing member is fixed over the entire longitudinal or lateral direction of the battery element, but it is not necessarily limited thereto. This will be described later with reference to other drawings. In the case of the reinforcing member shape as shown in FIG. 4A, as an example, the width dimension is preferably 1.0 mm or more, and more preferably 2.0 mm or more.

  The reinforcing member is fixed to the battery element. The fixing method is not particularly limited, but adhesion with an adhesive, fixation with a fixing member such as a tape, welding, caulking, a screw or the like can be used. As schematically shown in FIG. 4B, the outer surface (upper surface in the drawing) of the reinforcing member 65 is not joined to the inner surface of the film sheath 10. As shown in FIG.

(Action)
In the film-clad battery 1 of this embodiment configured as described above, when a large amount of gas is generated in the film case 10 at the time of abnormality, the film case 10 first expands as shown in FIG. 4C. The length in the width direction (the length in the lateral direction of the drawing) of the internal space of the film package 10 at this time is shorter than the initial length. Such deformation due to expansion causes the inner surface of the outer covering film to be pressed against the cut portions 66a and 66b of the reinforcing member 65, whereby the outer covering film is perforated to form a gas discharge hole. Then, the internal gas is discharged to the outside through the gas discharge hole, and the internal pressure of the film package 10 is released.

  In the configuration of the present embodiment, in particular, since the reinforcing member 65 is formed to be longer than the battery element 20, even if the film case 10 is expanded as shown in FIG. Abut on. Therefore, no force in the direction of the arrow is applied to battery element 20 from the exterior film, so that deformation of battery element 20 and the occurrence of a short circuit due to the deformation are also prevented.

  As mentioned above, although one form of the present invention was explained, composition and shape of each part may be variously changed in the above-mentioned embodiment. For example, the reinforcing member 65 may have one end only as a cut portion and the other end as a non-cut portion (in one example, an end portion having a rectangular shape), instead of both ends as cut portions.

Second Embodiment
As shown in FIG. 6, the end of the reinforcing member 65 may be disposed so as to be pinched by a part of the film case 10. In this example, the cut portions 66 a and 66 b at both ends of the reinforcing member 65 are sandwiched between the two exterior films 10-1 and 10-2 at the flat portion 14 inside the heat sealing portion 15. There is. In the flat portion 14, the sheathed films are not heat-sealed with each other, and therefore, when gas is generated, the film sheathed body 10 expands as in the above embodiment (see FIG. 4C).

  According to such a configuration, since the portions of the cutting portions 66a and 66b are held by a part of the film sheath 10, it is intended even when an impact is applied to the battery at the time of use or transport. As a result, it is possible to prevent the exterior film from being perforated by the cutting portion.

  The flat portion 14 of FIG. 6 may be formed during a vacuuming process after injecting the electrolytic solution into the outer package, or may be separately formed by performing a pressing process, etc. It is also good. The flat portion 14 is formed, for example, in an inner region adjacent to the heat sealing portion 15. The flat portion 14 may be partially formed only in the portion sandwiching the cutting portions 66a and 66b (not shown), and as schematically shown in FIG. It may be formed. In FIG. 6, the cutting portions 66 a and 66 b and the vicinity thereof are sandwiched by the flat portion 14. However, only a part of the cutting portions 66 a and 66 b may be sandwiched.

Third Embodiment
The number, direction, shape, etc. of the reinforcing members 65 fixed to the battery element can be changed variously. For example, as shown in FIG. 7, the film-clad battery may have two reinforcing members 65-1 and 65-2 fixed to the battery element 20. In this example, two reinforcing members 65-1 and 65-2 are disposed substantially in parallel at predetermined intervals. The length, thickness, end shape, material, and the like of each of the reinforcing members 65-1 and 65-2 may be the same or different. Of course, three or more reinforcing members may be disposed.

  Further, as shown in FIG. 8, one or more reinforcing members may be arranged in different directions. In FIG. 8A, the first reinforcing member 65 disposed in the width direction of the battery element and the second reinforcing member 67 disposed in the longitudinal direction (longitudinal direction) of the battery element are included. In FIG. 8 (b), two first reinforcing members 65 are further arranged.

(Other forms)
(1) The reinforcing member may not necessarily be fixed over the entire side of the battery element. For example, as in the reinforcing member 68 of FIG. 9A, only a part of the width of the battery element (for example, 50% or more, 75% or more, or 90% or more of the width dimension) is fixed, and one end is a cut portion 68a It is good also as composition projected as. Naturally, the reinforcing members may be arranged longitudinally.

(2) Also, as shown in FIG. 9 (b), the reinforcing members 68-1 and 68-2 configured as described above are disposed in opposite directions, and the cut portions 68a and 68a correspond to the battery element 20. It may be arranged to project on both sides of the The number of reinforcing members may be three or more. Although the reinforcing members arranged in the width direction have been described, the reinforcing members may be arranged in the longitudinal direction (longitudinal direction) in this manner.

(3) In the above embodiment, one or a plurality of elongated plate-like reinforcing members are arranged, but a member having a wider area may be used as a reinforcing member. In the example of FIG. 10, a reinforcing member 69 that covers the entire surface of the battery element 20 is fixed to the battery element 20. The reinforcing member 69 has cut portions 69a, 69b, 69c on three sides of the outer periphery of the battery element 20 in this example. A plurality of cutting portions may be formed on each side as illustrated. Naturally, the cutting portion may be provided not on all three sides but only on at least one side.

  As mentioned above, although the film-clad battery which concerns on this invention as several embodiment was demonstrated, you may combine the characteristic part of one embodiment with the structure of other embodiment in the range which does not deviate from the meaning of this invention.

(Supplementary note)
The present application discloses the following inventions:
1. A battery element (20) comprising a positive electrode, a negative electrode, and a separator;
A film case (10) containing the battery element;
A reinforcing member (65) formed with a cutting portion (66) capable of perforating the film casing in contact with the film casing, and directly or indirectly fixed to the battery element;
A secondary battery comprising the

  According to such a configuration, when the film case expands due to gas generation, the inner surface of the case film is pressed against the cut portion of the reinforcing member, whereby the case film is perforated and the gas is discharged. It can be performed. Further, the reinforcing member can also prevent the deformation of the battery element.

2. The secondary battery as described above, wherein the reinforcing member (65) has a plurality of cut portions (66a, 66b, 69, etc.) which abut on the film sheath.

3. The secondary battery as described above, comprising a plurality of the reinforcing members (65-1, 65-2).

4. The outline shape of the battery element (20) is a square,
The secondary battery as described above, wherein the reinforcing member (65) is fixed over the entire longitudinal or lateral side of the battery element.

5. The secondary battery as described above, wherein the reinforcing member has the cut portions (66a, 66b) formed at both ends.

6. The film case (10) is
The secondary battery as described above, comprising a flat portion (14) which at least partially sandwiches the cut portion (66) of the reinforcing member.

7. The cutting unit (66) is
The secondary battery as described above, wherein the film sheath is perforated when the film sheath is expanded and deformed due to the generation of gas.

8. The secondary battery as described above, wherein the reinforcing member (65) is not fixed to the inner surface of the film case. According to such a configuration, since the film sheathing body expands without being restrained by the reinforcing member, the film sheathing body can be favorably split at the cut portion of the reinforcing member.

  In the above description of the supplementary notes, the reference numerals in parentheses do not limit the present invention.

  The secondary battery according to an aspect of the present invention can be used, for example, in any industrial field that requires a power source. As an example, it can be used as a power source for mobile devices such as mobile phones and laptop computers; it can be used as a power source for electric vehicles such as electric cars, hybrid cars, electric bikes and electric assist bicycles; transport for transportation such as trains, satellites and submarines It can be used as a power source for storage media; it can be used as a storage system for storing power.

DESCRIPTION OF SYMBOLS 1 film exterior battery 10 film exterior 14 flat part 15 heat fusion part 20 battery element 25 separator 30 positive electrode 40 negative electrode 65, 67, 68, 69 reinforcement member 66, 66a, 66b cut part

Claims (8)

A battery element comprising a positive electrode, a negative electrode, and a separator;
A film case for housing the battery element;
A reinforcing member formed in a cutting portion capable of piercing the film outer package in contact with the film outer package and directly or indirectly fixed to the battery element;
A secondary battery comprising the   The secondary battery according to claim 1, wherein the reinforcing member has a plurality of cutting portions that abut the film sheath.   The secondary battery according to claim 1, comprising a plurality of the reinforcing members. The outline shape of the battery element is a square,
The secondary battery according to any one of claims 1 to 3, wherein the reinforcing member is fixed over the entire longitudinal or lateral side of the battery element.   The secondary battery according to any one of claims 1 to 4, wherein the cutting portion is formed at both ends of the reinforcing member. The film case is
The secondary battery according to any one of claims 1 to 5, further comprising a flat portion at least partially sandwiching the cut portion of the reinforcing member. The cutting unit is
The secondary battery according to any one of claims 1 to 6, wherein the film sheath is perforated when the film sheath is expanded and deformed due to the generation of gas.   The secondary battery according to any one of claims 1 to 7, wherein the reinforcing member is not fixed to the inner surface of the film case.

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