WO2017169130A1

WO2017169130A1 - Lamination type lithium ion battery

Info

Publication number: WO2017169130A1
Application number: PCT/JP2017/004309
Authority: WO
Inventors: 香織石川; 八木　弘雅; 渡邉　耕三; 藤原　勲
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2016-03-31
Filing date: 2017-02-07
Publication date: 2017-10-05
Also published as: JP2019091523A

Abstract

This lamination type lithium ion battery is provided with a lamination type electrode group including: a plurality of first electrodes and a plurality of second electrodes which are laminated alternately; and a long separator including a zig-zag folded portion which is folded in a zig-zag form so as to be interposed between the adjacent first and second electrodes, and including a first end which is one of the short sides thereof and a second end which is the other short side. The zig-zag folded portion does not cover at least one of a first principal surface and a second principal surface which intersect with the lamination direction of the electrode group.

Description

Stacked lithium-ion battery

The present invention relates to a lithium ion battery including a stacked electrode group.

2. Description of the Related Art As a stacked lithium ion battery, a configuration in which a long separator is arranged while being folded so as to be interposed between alternately stacked positive and negative electrodes is known. Patent Document 1 teaches that a zigzag separator is folded so as to cover the outermost plate (electrode) of the electrode group. As a result, the outermost electrode of the electrode group is easily impregnated with the electrolytic solution, and the electrical characteristics are improved.

Japanese translation of PCT publication No. 2004-503055

Usually, a multilayer electrode group is surrounded by a porous sheet such as a porous film. This is because the impregnation property of the liquid electrolyte is enhanced, the electrode group is prevented from being displaced, and the outermost electrode is protected. Therefore, the outer main surface of the outermost electrode of the electrode group shown in Patent Document 1 is covered with both the separator and the porous sheet.

In recent years, as electronic devices have become smaller and shorter, batteries connected to electronic devices are also required to be smaller and thinner. As described above, it is disadvantageous in terms of thickness reduction that the outer principal surface of the outermost electrode is covered with both the separator and the porous sheet. Furthermore, from the viewpoint of improving the impregnation property of the electrolyte solution into the electrode group, it is disadvantageous to cover the outer principal surface of the outermost electrode with both the separator and the porous sheet.

The stacked lithium ion battery according to one aspect of the present disclosure is folded in a manner to be interposed between a plurality of first electrodes and a plurality of second electrodes that are alternately stacked and between the adjacent first electrode and the second electrode. A laminated electrode group including a folded portion and a long separator having a first end that is one short side and a second end that is the other short side. The zigzag folded portion does not cover at least one of the first main surface and the second main surface that intersect in the stacking direction of the electrode group.

According to the present disclosure, since the thickness of the electrode group in the stacking direction can be reduced, the resulting stacked lithium ion battery can be thinned.

FIG. 1 is a cross-sectional view schematically showing an electrode group and a porous sheet surrounding the electrode group according to an embodiment of the present invention. FIG. 2 is an exploded perspective view schematically showing a part of the electrode group according to the embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing a part of the electrode group according to the embodiment of the present invention ((a) and (b)). FIG. 4 is a cross-sectional view schematically showing an electrode group according to another embodiment of the present invention. FIG. 5 is a perspective view schematically showing a stacked lithium ion battery according to an embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing a stacked lithium ion battery taken along line BB in FIG.

(Electrode group)
Hereinafter, the electrode group according to the present embodiment will be described with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing an electrode group 10 and a porous sheet 70 surrounding the electrode group 10 according to the present embodiment. FIG. 2 is an exploded perspective view schematically showing a part of the electrode group 10 according to the present embodiment. 3A and 3B are cross-sectional views schematically showing a part of the electrode group 10 according to the present embodiment. In the figure, the same reference numerals are given to components having the same function.

The electrode group 10 includes a plurality of first electrodes 11 and a plurality of second electrodes 12 stacked alternately, and a separator 13 interposed between the adjacent first electrode 11 and second electrode 12. The separator 13 is a long body, and has a serpentine folding portion 131 that is serpentinely folded while sandwiching one of the first electrode 11 and the second electrode 12. For example, 10 to 50 first electrodes 11 and second electrodes 12 are laminated.

As shown in FIG. 2, the zigzag folding portion 131 includes a planar region 131 a that faces at least a part of at least one main surface of the first electrode 11 and the second electrode 12 in the separator 13, and one first electrode. The bent regions 131b that face at least a part of the end surface of the eleventh or one second electrode 12 (the surface that intersects the main surface) are alternately disposed portions. The bent region 131b is a region sandwiched between two lines L1 and L2 formed by the plane passing through the end face of the electrode and the separator 13 intersecting each other. When the planar region 131a and a part of the bent region 131b overlap, the overlapping region (the hatched region in FIG. 2) may be regarded as the planar region 131a.

The zigzag folding part 131 does not cover at least one of the first main surface S1 and the second main surface S2 that intersects the stacking direction X of the electrode group 10 (see FIG. 1). Therefore, even when the periphery of the electrode group 10 is surrounded by a porous sheet 70 such as a porous film, at least one of the first main surface S1 and the second main surface S2 is covered only with the porous sheet 70. Therefore, the obtained lithium ion battery 100 can be thinned. Especially, it is preferable that neither the 1st main surface S1 nor the 2nd main surface S2 is covered with the zigzag folding part 131 from a viewpoint of thickness reduction.

Here, not covering the first main surface S1 or the second main surface S2 allows the zigzag folding portion 131 to be slightly applied to the end of each main surface. This is because it cannot be said that the zigzag folded portion 131 substantially covers the main surface. Specifically, as shown in FIG. 3, when the width of the first main surface S1 in the longitudinal direction Y is W, the zigzag folding portion 131 (or the first end portion 13X) is W × the first main surface S1. When facing a region of 1/10 or less, it cannot be said that the zigzag folded portion 131 covers the first main surface S1. Similarly, when the zigzag fold 131 faces the region of 1/10 or less of the width of the second main surface S2 in the longitudinal direction Y, the zigzag fold 131 is also the second main surface S2. It cannot be said that the surface S2 is covered.

In addition, in the example of illustration, although the 1st electrode 11 is arrange | positioned at the outermost part of both the electrode groups 10, it is not limited to this. For example, the outermost electrode group 10 may be the second electrode 12, one may be the first electrode 11, and the other may be the second electrode 12. In addition, the size of the main surface of the first electrode 11 may be larger, smaller, or the same as the size of the main surface of the second electrode 12.

Hereinafter, the first embodiment in which the separator 13 includes the zigzag folding portion 131 and the second embodiment in which the separator 13 includes the zigzag folding portion 131 and the outer peripheral portion 132 will be described in order.

[First Embodiment]
First, the first embodiment will be described with continued reference to FIGS.

In the present embodiment, the separator 13 is composed of a zigzag folding portion 131. That is, the first end surface 13X which is one short side (side intersecting the longitudinal direction Y) of the separator 13 and the second end portion 13Y which is the other short side are both the first main surface S1 and the second main surface. Does not face the surface S2 (FIG. 1), or faces a region from the side closer to the bent region 131b of the first main surface S1 and the second main surface S2 to 1/10 of the width W of each main surface (FIG. 3A).

Among these, from the viewpoint of reducing the thickness, it is preferable that at least one of the first end portion 13X and the second end portion 13Y is disposed between the first main surface S1 and the second main surface S2. In particular, it is preferable that the first end portion 13X and the second end portion 13Y are both disposed between the first main surface S1 and the second main surface S2. Between the first main surface S1 and the second main surface S2, as shown in FIGS. 3A and 3B, a plane including the first main surface S1 and a plane including the second main surface S2 It is the area | region R pinched | interposed by. That is, it is not necessary that the first end portion 13X is disposed between the first main surface S1 and the second main surface S2 until the first end portion 13X faces the first main surface S1. As shown in FIG. 3B, the first end portion 13X may be in a position that does not face any electrode of the first main surface S1 and further the second main surface S2. Similarly, it is not necessary that the second end portion 13Y is disposed between the first main surface S1 and the second main surface S2 until the second end portion 13Y faces the second main surface S2. . The second end portion 13Y may be in a position that does not oppose any electrode of the second main surface S2 and further the first main surface S1.

In this embodiment, as shown in FIG. 1, the electrode group 10 is preferably surrounded by a porous sheet 70. In this case, the electrode group 10 is wound by the porous sheet 70 in a direction that avoids the side where the negative electrode tab and the positive electrode tab described later extend. This is because the electrode group 10 is protected from external factors and the displacement between the electrodes is suppressed. From the above viewpoint, it is preferable that the porous sheet 70 surrounds the electrode group 10 one or more times. The ends of the porous sheet 70 are joined together by, for example, an insulating tape or heat welding.

The material of the porous sheet 70 is not particularly limited as long as it has insulating properties, and may be the same as or different from the separator 13. Further, from the viewpoint of impregnation properties when using an electrolyte containing a liquid, the porous sheet 70 is preferably as porous as possible. For example, the porosity of the porous sheet 70 is preferably 40% or more, and more preferably 60% or more. In consideration of the mechanical strength of the porous sheet 70, the protection of the electrode group 10, and the suppression of displacement between the electrodes, the porosity of the porous sheet 70 is preferably 80% or less, and 70% or less. Is more preferable.

On the other hand, the porosity of the separator 13 disposed between the electrodes is preferably not excessively large from the viewpoint of preventing an internal short circuit. For example, the porosity of the separator 13 is preferably 60% or less, and more preferably 55% or less. In consideration of the impregnation property when an electrolyte containing a liquid is used, the porosity of the separator 13 is preferably 30% or more, and more preferably 40% or more.

The porosity is a porosity, that is, a value calculated by the following formula.

Porosity = (1−total volume of material constituting porous sheet / apparent volume of porous sheet) × 100 [%]
As described above, the porous material (that is, the separator 13) disposed between the electrodes and the porous material (that is, the porous sheet 70) surrounding the electrode group 10 are separated from each other according to the purpose. The porosity can be selected. For example, by selecting a material having a larger porosity than that of the separator 13 as the porous sheet 70, both impregnation and prevention of internal short circuit can be achieved. The specific configurations of the separator 13 and the porous sheet 70 will be described later.

[Second Embodiment]
Next, a second embodiment will be described with reference to FIG. FIG. 4 is a cross-sectional view schematically showing an electrode group 10A according to this embodiment.

In the present embodiment, the separator 13A includes a zigzag folded portion 131 and an outer peripheral portion 132. The outer peripheral portion 132 has a first end portion 13 </ b> X that is one end portion of the separator 13 </ b> A, and extends from the zigzag folding portion 131. The zigzag fold 131 has a second end 13Y which is the other end of the separator 13A.

As shown in FIG. 4, for example, when the second end portion 13Y is on the second main surface S2 side, the separator 13A includes the first main surface S1 while being folded from the second end portion 13Y as a starting point. 11 A and the second electrode 12 </ b> A adjacent thereto extend so as to be interposed, and a zigzag fold 131 is formed. Subsequently, the separator 13A extends in a direction toward the second main surface side, and as it is, a plurality of stacked electrodes (the first electrode 11 and the second electrode 12) and a zigzag folding portion 131 (hereinafter, together with the stacked body) The outer peripheral portion 132 is formed. That is, the zigzag folding part 131 and the outer peripheral part 132 are continuous. The boundary D between the zigzag folded portion 131 and the outer peripheral portion 132 is substantially opposed to the end portion of the first electrode 11A, and is located in the vicinity of the first main surface S1.

Specifically, the outer peripheral portion 132 includes a first region 132a that covers from one end face of the second electrode 12A to the end face on the same side of the first electrode 11B having the second main face S2, and a second main part 132a. The second region 132b that covers the surface S2, and the third region that covers from the other end surface of the first electrode 11B on the different side to the end surface of the first electrode 11A on the same side as the other end surface of the first electrode 11B. 132c and a fourth region 132d covering the first main surface S1 are provided in this order from the boundary D.

Also in this case, since the first main surface S1 and the second main surface S2 are covered only with the outer peripheral portion 132, the obtained lithium ion battery 100 can be thinned. In addition, the boundary D (that is, one end portion of the outer peripheral portion 132) is located on the end surface along the stacking direction X of the electrode group 10A. For this reason, when the ends of the outer peripheral portion 132 are joined and fastened, the other end portion (first end portion 13X) of the outer peripheral portion 132 is also disposed on the end surface along the stacking direction X of the electrode group 10A. That's fine. That is, the overlap between the end portions of the outer peripheral portion 132 can be disposed between the first main surface S1 and the second main surface S2. Therefore, it becomes easy to make a lithium ion battery thin.

Further, the separator 13A according to the present embodiment has two functions of the separator 13 and the porous sheet 70 in the first embodiment. That is, by preparing a separator 13A that is longer than the separator 13, it is possible to perform an operation of surrounding the outer periphery of the obtained laminate on the extension of the operation of interposing the separator 13A between the electrodes. Therefore, productivity is improved.

(Stacked lithium-ion battery)
Hereinafter, with reference to FIGS. 2, 5, and 6, the case where the first electrode 11 is a negative electrode and the second electrode 12 is a positive electrode is taken as an example. A lithium ion battery (hereinafter simply referred to as a lithium ion battery 100) will be described. FIG. 5 is a perspective view schematically showing the external appearance of the lithium ion battery 100. 6 is a cross-sectional view schematically showing the lithium ion battery 100 taken along line BB in FIG. 6 shows a case where the lithium ion battery 100 includes two electrode groups 10, the number of the electrode groups 10 is not limited to this, and one or more electrode groups may be included.

In the lithium ion battery 100, the electrode group 10 is housed in a battery case 20 including a rectangular metal container 21 having a bottom and an opening and a lid 22 that closes the opening of the metal container 21. One end of the negative electrode terminal 30 protrudes from one end of the lid portion 22, and one end of the positive electrode terminal 40 protrudes from the other end. The ends of the negative electrode terminal 30 and the positive electrode terminal 40 that protrude from the lid 22 are each formed into a rivet shape, whereby the negative electrode terminal 30 and the positive electrode terminal 40 are fixed to the lid 22 via

washers

50A or 50B. . The negative electrode terminal 30 and the positive electrode terminal 40, and the negative electrode current collecting plate 31 and the positive electrode current collecting plate (not shown) are provided with thread grooves (not shown) to be engaged with each other, and fixed to the lid 22. Also good. The negative electrode terminal 30 and the positive electrode terminal 40 are insulated from the lid 22 by insulating gaskets 61 and 62 (see FIG. 6).

On the other hand, the other end of the negative electrode terminal 30 inserted into the battery case 20 is electrically connected to the negative electrode current collector plate 31. Similarly, the other end of the positive electrode terminal 40 is electrically connected to a positive current collector plate (not shown). A current interrupting mechanism (not shown) such as a fuse may be connected to at least one of a connection path between the negative electrode terminal 30 and the negative electrode current collector plate 31 and a connection path between the positive electrode terminal 40 and the positive electrode current collector plate. .

An insulating gasket 63 is interposed between the negative electrode current collector plate 31 and the lid 22 to insulate the negative electrode current collector plate 31 from the lid 22. Further, an insulating insulating container 80 may be disposed so as to cover the inner surface of the metal container 21. The insulating container 80 has a square shape having a bottom and an opening, and insulates the electrode group 10 from the metal container 21. Further, the surface of the electrode group 10 that contacts the inner wall surface of the insulating container 80 is surrounded by the porous sheet 70 (or the outer peripheral portion 132 of the separator 13A). Thereby, while insulating the electrode group 10 and the metal container 21, the gap | deviation of the laminated | stacked electrodes is prevented and the damage by the contact with the insulating container 80 of the electrode group 10, etc. is suppressed.

Each negative electrode 11 constituting the electrode group 10 is electrically connected to a negative electrode current collector 31 via a negative electrode lead wire 32. Similarly, the positive electrode 12 is electrically connected to the positive electrode current collector plate via a positive electrode lead wire (not shown). The negative electrode lead wire 32 is joined to the negative electrode tab 111b (see FIG. 2) of the negative electrode 11. A plurality of negative electrode lead wires 32 joined to the negative electrode tab 111b of each negative electrode 11 constituting one electrode group 10 are electrically connected to each other by welding or the like, and then are connected to, for example, the electrode group 10 of the negative electrode current collector plate 31. Bonded to the opposite surface. Similarly, the positive electrode lead wire is bonded to the surface of the positive electrode current collector plate facing the electrode group 10. When the plurality of electrode groups 10 are accommodated in the metal container 21, the electrode groups 10 are arranged such that one main surfaces intersecting the stacking direction X of the electrode groups 10 face each other. Instead of using each lead wire, the tabs of each electrode may be sufficiently long and welded together, and then joined to each current collector plate.

When the lithium ion battery 100 is assembled, first, the negative electrode terminal 30 and the negative electrode current collector plate 31, the positive electrode terminal 40 and the positive electrode current collector plate are bonded to a predetermined portion of the lid 22 with gaskets (61, 62 and 63) interposed therebetween. Fix each of the locations. Separately, the electrode group 10 is produced, each lead wire is joined to the electrode group 10, and the lead wires are joined together. Next, the integrated lead wire is joined to each current collector plate fixed to the lid 22. Thereafter, the electrode group 10 is impregnated with the electrolytic solution, and the electrode group 10 containing the electrolytic solution is inserted into the insulating container 80. Finally, the electrode group 10 is accommodated in the metal container 21 together with the insulating container 80, and the metal container 21 and the lid 22 are joined and sealed by welding or the like. The impregnation with the electrolytic solution may be performed after the electrode group 10 is accommodated in the metal container 21.

(Battery case)
The material of the metal container 21 and the metal container 21 constituting the battery case 20 is not particularly limited, and examples thereof include iron and stainless steel. The materials of the metal container 21 and the metal container 21 may be different from each other, but are preferably the same from the viewpoint of bonding strength and the like. The shape and size of the metal container 21 are not particularly limited, and may be set as appropriate according to the application, the shape and size of the electrode group 10, and the like. The thickness of the wall surface of the metal container 21 is not particularly limited, and is, for example, 0.5 to 1.5 mm.

(Negative electrode)
As shown in FIG. 2, the negative electrode 11 includes a negative electrode core material 111 and a negative electrode active material layer 112 formed on both surfaces of the negative electrode core material 111. The negative electrode core 111 includes a negative electrode main body 111a and a negative electrode tab 111b extending from a part of the negative electrode main body 111a. The negative electrode active material layer 112 is not formed on at least a part of both surfaces of the negative electrode tab 111b. When the negative electrode lead wire 32 is used, one end of the negative electrode lead wire 32 is joined to the negative electrode tab 111b by resistance welding or the like. Note that the negative electrode active material layer 112 may be formed only on one surface of the negative electrode main body 111a.

The negative electrode core material 111 is a porous or non-porous conductive substrate. As a material of the negative electrode core material 111, for example, a metal foil such as stainless steel, nickel, copper, copper alloy, and aluminum is preferably used. The thickness of the negative electrode core material 111 is not particularly limited, but is preferably 5 μm to 20 μm.

The negative electrode active material layer 112 includes a negative electrode active material as an essential component, and includes a binder, a conductive agent, and the like as optional components. As the negative electrode active material, metallic lithium, an alloy (such as a silicon alloy or a tin alloy), a carbon material (such as graphite or hard carbon), a silicon compound, a tin compound, or a lithium titanate compound is used. When forming the negative electrode active material layer 112, a negative electrode mixture containing a negative electrode active material is mixed with a liquid component to prepare a negative electrode slurry. Next, the negative electrode slurry is applied to both surfaces of the negative electrode main body 111a to dry the coating film. Next, the dried coating film is rolled together with the negative electrode core material 111 to form the negative electrode active material layer 112 having a predetermined thickness. The thickness of the negative electrode active material layer 112 is not particularly limited, but is preferably 70 μm to 150 μm. Note that when the negative electrode active material is an alloy or a compound, the negative electrode active material layer 112 may be formed by a vacuum process.

(Positive electrode)
The positive electrode 12 includes a positive electrode core material 121 and a positive electrode active material layer 122 formed on both surfaces of the positive electrode core material 121. The positive electrode core member 121 includes a positive electrode main body 121a and a positive electrode tab 121b extending from a part of the positive electrode main body 121a. The positive electrode active material layer 122 is not formed on both surfaces of the positive electrode tab 121b. When using the positive electrode lead wire, one end of the positive electrode lead wire is joined to the positive electrode tab 121b by resistance welding or the like. The positive electrode active material layer 122 may be formed only on one surface of the positive electrode main body 121a.

The positive electrode core material 121 is a porous or non-porous conductive substrate. As the material of the positive electrode core material 121, for example, a metal foil such as aluminum or an aluminum alloy is preferably used. The thickness of the positive electrode core material 121 is not particularly limited, but is preferably 10 μm to 20 μm.

The positive electrode active material layer 122 includes a positive electrode active material as an essential component, and includes a binder, a conductive agent, and the like as optional components. As the positive electrode active material of the lithium ion secondary battery, a lithium-containing composite oxide is preferable, and for example, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O _{4 and the} like are used. As the positive electrode active material of the lithium ion primary battery, manganese dioxide, graphite fluoride, or the like is used. When the positive electrode active material layer 122 is formed, a positive electrode slurry containing a positive electrode active material is mixed with a liquid component to prepare a positive electrode slurry. Next, the positive electrode slurry is applied to both surfaces of the positive electrode main body 121a to dry the coating film. Next, the dried coating film is rolled together with the positive electrode core material 121 to form the positive electrode active material layer 122 having a predetermined thickness. The thickness of the positive electrode active material layer 122 is not particularly limited, but is preferably 70 μm to 130 μm.

Examples of the binder that can be included in the negative electrode active material layer 112 and / or the positive electrode active material layer 122 include, for example, a fluororesin (polyvinylidene fluoride, polytetrafluoroethylene, etc.), polyamide, polyimide, polyamideimide, polyacrylic acid, Examples include styrene butadiene rubber. Examples of the conductive agent that can be included in the negative electrode active material layer 112 and / or the positive electrode active material layer 122 include graphite, carbon black, and carbon fiber.

(Separator)
As the separator 13, an insulating microporous thin film, a woven fabric, or a non-woven fabric is used. The microporous thin film may be a single layer film or a multilayer film. As a material for the separator 13, for example, polyolefin such as polypropylene and polyethylene is preferably used. This is because polyolefin is excellent in durability and has a shutdown function. The thickness of the separator 13 is not particularly limited, and is, for example, 10 μm to 300 μm, preferably 10 to 40 μm, more preferably 10 to 25 μm. The length of the separator 13 in the longitudinal direction Y is not particularly limited as long as it can be interposed between the negative electrode and the positive electrode stacked at least while being folded.

(Electrolytes)
The electrolyte may be in a liquid, gel, or solid state.

The liquid electrolyte is usually composed of a lithium salt and a non-aqueous solvent in which the lithium salt is dissolved. The non-aqueous solvent is not particularly limited, and cyclic carbonates, chain carbonates, cyclic carboxylic acid esters, and the like are used. Examples of the cyclic carbonate include propylene carbonate and ethylene carbonate. Examples of the chain carbonate include diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate. Examples of the cyclic carboxylic acid ester include γ-butyric lactone and γ-valerolactone. Examples of the lithium salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiCF ₃ CO _{2 and the} like.

The gel electrolyte is usually composed of a polymer matrix, and the solvent and lithium salt impregnated in the polymer matrix. The solid electrolyte is usually composed of a polymer matrix and the lithium salt contained in the polymer matrix.

The material used for the polymer matrix (matrix polymer) is not particularly limited, and for example, a material that gels by absorbing the liquid electrolyte can be used. Specific examples include a fluororesin containing a vinylidene fluoride unit, an acrylic resin containing a (meth) acrylic acid and / or (meth) acrylic acid ester unit, and a polyether resin containing a polyalkylene oxide unit.

Examples of the fluororesin containing a vinylidene fluoride unit include polyvinylidene fluoride (PVdF), a copolymer (VdF-HFP) containing a vinylidene fluoride (VdF) unit and a hexafluoropropylene (HFP) unit, and vinylidene fluoride (VdF). ) Units and trifluoroethylene (TFE) units.

(Negative lead wire)
The material of the negative electrode lead wire 32 is not particularly limited as long as it is electrochemically and chemically stable and has conductivity, and may be a metal or a nonmetal. Among these, a metal foil is preferable. Examples of the metal foil include copper foil, copper alloy foil, and nickel foil. The thickness of the negative electrode lead wire 32 is preferably 25 to 200 μm, more preferably 50 to 100 μm.

(Positive lead wire)
The material of the positive electrode lead wire is not particularly limited as long as it is electrochemically and chemically stable and has conductivity, and may be a metal or a nonmetal. Among these, a metal foil is preferable. Examples of the metal foil include aluminum foil, aluminum alloy foil, nickel, nickel alloy, iron, and stainless steel. The thickness of the positive lead wire is preferably 25 to 200 μm, more preferably 50 to 100 μm.

(gasket)
The material of the

gaskets

61, 62 and 63 is not particularly limited. For example, polypropylene (PP), polyethylene (PE), polyphenylene sulfide (PPS), perfluoroalkylethylene-hexafluoropropylene copolymer (PFA), crosslinked type Rubber etc. are mentioned. Among these, PFA is preferable because it has low moisture permeability and can suppress the ingress of moisture into the battery case.

(Porous sheet)
As the porous sheet 70, an insulating microporous thin film, woven fabric or non-woven fabric is used. Examples of the material of the porous sheet 70 include the materials exemplified for the separator 13. The thickness of the porous sheet 70 is not particularly limited, and is, for example, 10 to 300 μm, and preferably 10 to 50 μm.

(Insulated container)
The material of the insulating container 80 is not particularly limited, and examples thereof include polypropylene (PP), polyethylene (PE), polyphenylene sulfide (PPS), perfluoroalkylethylene-hexafluoropropylene copolymer (PFA), and the like. The thickness, shape, and size of the wall surface of the insulating container 80 are not particularly limited, and may be set as appropriate according to the application, the shape, size, and the like of the electrode group 10.

The lithium ion battery of the present invention can be used in the same applications as conventional lithium ion batteries, and is particularly useful as a main power source or auxiliary power source for electronic devices, electrical devices, machine tools, transportation devices, power storage devices, and the like. Electronic devices include personal computers, mobile phones, mobile devices, portable information terminals, portable game devices, and the like. Electrical equipment includes vacuum cleaners and video cameras. Machine tools include electric tools and robots. Transportation equipment includes electric vehicles, hybrid electric vehicles, plug-in HEVs, fuel cell vehicles, and the like. Examples of power storage devices include uninterruptible power supplies.

100

Lithium ion battery

10,

10A Pole group

11, 11A, 11B First electrode (negative electrode)
DESCRIPTION OF SYMBOLS 111 Negative electrode core material 111a Negative electrode main-body part 111b Negative electrode tab 112 Negative electrode

active material layer

12, 12A 2nd electrode (positive electrode)
121 positive electrode core material 121a positive electrode main body part 121b positive electrode tab 122 positive electrode

active material layer

13, 13A separator 13X first end part 13Y second end part 131 zigzag folding part 131a flat area 131b bending area 132 outer peripheral part 132a first area 132b second area 132c Third region 132d Fourth region 20 Battery case 21 Metal container 22 Lid 30 Negative electrode terminal 31 Negative electrode current collector plate 32 Negative electrode lead wire 40

Positive electrode terminal

50A,

50B Washers

61, 62, 63 Gasket 70 Porous sheet 80 Insulating container

Claims

A plurality of first electrodes and a plurality of second electrodes that are alternately stacked, and a zigzag folded portion that is zigzag folded so as to be interposed between the adjacent first electrode and the second electrode, and one short side A long separator having a first end that is and a second end that is the other short side;
Including a stacked electrode group including
The stacked lithium ion battery, wherein the zigzag folded portion does not cover at least one of the first main surface and the second main surface intersecting in the stacking direction of the electrode group.
The zigzag folded portion does not cover at least the first main surface;
The separator further includes an outer peripheral portion extending from the zigzag fold and having the first end;
The zigzag fold has the second end;
The second end is located on the second main surface side;
A boundary between the zigzag folded portion and the outer peripheral portion is located on the first main surface side,
The outer peripheral portion extends from the boundary in a direction from the first main surface toward the second main surface so as to surround the periphery of the electrode group at least once. The laminated lithium ion battery described.
The stacked lithium ion battery according to claim 1 or 2, wherein the zigzag folded portion does not cover either the first main surface or the second main surface.
The stacked lithium ion battery according to claim 3, wherein the first end portion and the second end portion are respectively disposed between the first main surface and the second main surface.
The multilayer lithium ion battery according to claim 1, further comprising a porous sheet surrounding the electrode group at least once.
The multilayer lithium ion battery according to claim 5, wherein the porosity of the porous sheet is larger than the porosity of the separator.
The porosity of the separator is 30-60%,
The multilayer lithium ion battery according to claim 6, wherein the porosity of the porous sheet is 40 to 80%.