JP2019091523A - Laminated lithium-ion battery - Google Patents

Abstract

To provide a laminated lithium-ion battery whose thickness is small in the lamination direction of an electrode group.SOLUTION: A laminated lithium-ion battery includes a laminated electrode group which includes: a plurality of first electrode and a plurality of second electrodes which are alternately laminated; and a long-sized separator which has a zigzag part folded in the zigzag state so as to be interposed between the first electrode and the second electrode adjacent to each other and has a first end which is one short side and a second end which is the other short end. The zigzag part does not cover at least one of a first main surface and a second main surface intersecting with each other in the lamination direction of the electrode group.SELECTED DRAWING: Figure 1

Description

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

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

Japanese Patent Publication No. 2004-503055

  Usually, the laminated electrode group is surrounded by a porous sheet such as a porous film. This is for the purpose of enhancing the impregnation of the liquid electrolyte, preventing the displacement of the electrode group, and protecting the outermost electrode. Therefore, the outer major surface of the outermost electrode of the electrode group shown in Patent Document 1 is covered with both the separator and the porous sheet.

  2. Description of the Related Art In recent years, with the downsizing and shortening of electronic devices, the downsizing and thinning of batteries connected to electronic devices are also required. As described above, covering the outer main surface of the outermost electrode with both the separator and the porous sheet is disadvantageous in terms of thinning. Furthermore, covering the outer main surface of the outermost electrode with both the separator and the porous sheet works disadvantageously also from the viewpoint of enhancing the infiltration of the electrolyte into the electrode group.

  One aspect of the present invention includes a plurality of alternately stacked first electrodes and a plurality of second electrodes, and a serpentine folded portion interposed between the adjacent first electrodes and the second electrodes. A stack-type electrode group including: an elongated separator having a first end which is one short side and a second end which is the other short side; It is a lamination type lithium ion battery which does not cover at least 1 side of the 1st principal surface and the 2nd principal surface which intersect in the lamination direction of an electrode group.

  According to the present invention, since the thickness in the stacking direction of the electrode group can be reduced, the obtained laminated lithium ion battery can be thinned.

It is sectional drawing which shows typically the porous sheet which encloses the electrode group which concerns on embodiment of this invention, and an electrode group. It is a disassembled perspective view which shows typically a part of electrode group which concerns on embodiment of this invention. It is sectional drawing which shows typically a part of electrode group which concerns on embodiment of this invention ((a) and (b)). It is sectional drawing which shows typically the electrode group which concerns on other embodiment of this invention. FIG. 1 is a perspective view schematically showing a laminated lithium ion battery according to an embodiment of the present invention. It is sectional drawing which shows typically the laminated type lithium ion battery in the BB line of FIG.

(Electrode group)
Hereinafter, the electrode group according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a cross-sectional view schematically showing an electrode group 10 according to the present embodiment and a porous sheet 70 surrounding the electrode group 10. FIG. 2 is an exploded perspective view schematically showing a part of the electrode group 10 according to the present embodiment. Fig.3 (a) and (b) are sectional drawings which show typically a part of electrode group 10 which concerns on this embodiment. In the drawings, components having the same function are denoted by the same reference numerals.

  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 electrodes 11 and the second electrodes 12. The separator 13 is a long body, and includes a serpentine portion 131 that is zigzag folded while sandwiching one of the first electrode 11 and the second electrode 12. For example, 10 to 50 sheets of the first electrode 11 and the second electrode 12 are stacked, respectively.

  As illustrated in FIG. 2, the zigzag portion 131 is a flat region 131 a of the separator 13 that faces at least a part of at least one of the main surfaces of the first electrode 11 and the second electrode 12, and one first electrode. The bent regions 131 b facing at least a part of the end face (the face intersecting with the main surface) of the 11 or one second electrode 12 are portions arranged alternately. The bent region 131 b is a region sandwiched by two lines L 1 and L 2 formed by crossing the plane passing through the end face of the electrode and the separator 13. When the flat area 131a and a part of the bending area 131b overlap, the overlapping area (the hatched area in FIG. 2) may be regarded as the flat area 131a.

  The zigzag portion 131 does not cover at least one of the first main surface S1 and the second main surface S2 intersecting the stacking direction X (see FIG. 1) of the electrode group 10. Therefore, even when the periphery of the electrode group 10 is surrounded by the 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 with the porous sheet 70 alone. As a result, it is possible to make the obtained lithium ion battery 100 thinner. Among them, it is preferable that neither the first main surface S1 nor the second main surface S2 be covered by the serpentine portion 131 from the viewpoint of thinning.

  Here, not covering the first main surface S1 or the second main surface S2 allows the serpentine portion 131 to be slightly applied to the end portion of each main surface. In this case, it can not be said that the zigzag 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 serpentine portion 131 (or the first end 13X) is W × of the first main surface S1. When facing the 1/10 or less area | region, it can not be said that the zigzag part 131 has covered 1st main surface S1. Similarly to the second main surface S2, in the case where the zigzag portion 131 faces the area of 1/10 or less of the width of the second main surface S2 in the longitudinal direction Y, the zigzag portion 131 is a second main It can not be said that the surface S2 is covered.

  In addition, although the 1st electrode 11 is arrange | positioned at the outermost of both the electrode groups 10 in the example of illustration, it is not limited to this. For example, the outermost of the electrode group 10 may be all the second electrodes 12, or one may be the first electrode 11 and the other may be the second electrode 12. 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 serpentine portion 131 and the second embodiment in which the separator 13 includes the serpentine 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. 1 and 3.
In the present embodiment, the separator 13 is configured of a zigzag portion 131. That is, the first end 13X, which is one short side (a side intersecting the longitudinal direction Y) of the separator 13, and the second end 13Y, which is the other short side, both have the first main surface S1 and the second main surface. Does not face the surface S2 (FIG. 1) or faces the region from the side closer to the bending 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. 3 (a)).

  Among them, it is preferable that at least one of the first end 13X and the second end 13Y be disposed between the first main surface S1 and the second main surface S2 from the viewpoint of thinning. In particular, it is preferable that the first end 13X and the second end 13Y are both disposed between the first major surface S1 and the second major 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 Region R sandwiched between That is, the fact that the first end 13X is disposed between the first main surface S1 and the second main surface S2 does not require the first end 13X to be opposed to the first main surface S1. As shown in FIG. 3B, the first end 13X may not be opposed to any of the electrodes of the first main surface S1 and further the second main surface S2. Similarly, the fact that the second end 13Y is disposed between the first main surface S1 and the second main surface S2 does not require the second end 13Y to be opposed to the second main surface S2. . The second end 13Y may be located at a position not facing the second main surface S2, and further, neither electrode of the first main surface S1.

  In the present 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 around the porous sheet 70 in a direction to avoid the side on which the negative electrode tab and the positive electrode tab described later extend. It is for the protection from the external factor of the electrode group 10, and for suppressing the shift | offset | difference of electrodes. From the above viewpoint, it is preferable that the porous sheet 70 encloses the periphery of the electrode group 10 one or more times. The end portions of the porous sheet 70 are joined 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. Moreover, from the viewpoint of the impregnatability in the case of using an electrolyte containing a liquid, the larger the porosity of the porous sheet 70, the better. 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 the displacement between the electrodes, the porosity of the porous sheet 70 is preferably 80% or less, and 70% or less. Is more preferred.

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

Porosity, that is, porosity, is a value calculated by the following equation.
Porosity = (1-total volume of the material constituting the porous sheet / apparent volume of the porous sheet) x 100 [%]

  Thus, according to the purpose, the porous material (i.e., the separator 13) disposed between the electrodes and the porous material (i.e., the porous sheet 70) surrounding the periphery of the electrode group 10 are separately provided. The porosity can be selected. For example, by selecting a material having a porosity higher than that of the separator 13 as the porous sheet 70, both the impregnation and the prevention of the 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 the present embodiment.
In the present embodiment, the separator 13A includes a zigzag portion 131 and an outer peripheral portion 132. The outer peripheral portion 132 has a first end 13X which is one end of the separator 13A, and extends from the serpentine portion 131. The zigzag portion 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 13Y is on the second main surface S2 side, the separator 13A is a first electrode provided with the first main surface S1 while being folded in a zigzag with the second end 13Y as a starting point. It extends so as to be interposed between the second electrode 12A and the second electrode 12A adjacent to the second electrode 12A to form a serpentine portion 131. Subsequently, the separator 13A extends in the direction toward the second main surface side, and as it is, the plurality of stacked electrodes (the first electrode 11 and the second electrode 12) and the serpentine portion 131 (hereinafter collectively referred to as a stacked body). ), And the outer circumferential portion 132 is formed. That is, the zigzag portion 131 and the outer peripheral portion 132 are continuous. The boundary D between the zigzag portion 131 and the outer peripheral portion 132 substantially faces the end 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 surface of the second electrode 12A to the end surface on the same side as the above of the first electrode 11B having the second main surface S2, and a second main Third region covering from the second region 132b covering the surface S2 and 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 132 c and a fourth region 132 d covering the first major surface S 1 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 by the outer peripheral portion 132, it is possible to reduce the thickness of the obtained lithium ion battery 100. Further, the boundary D (that is, one end of the outer peripheral portion 132) is located at an end face along the stacking direction X of the electrode group 10A. Therefore, when the end portions of the outer peripheral portion 132 are joined and wounded, 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. Just do it. 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 the lithium ion battery thinner.

  Further, the separator 13A according to the present embodiment has the two functions of the separator 13 and the porous sheet 70 in the first embodiment. That is, by preparing the separator 13A longer than the separator 13, the operation of surrounding the outer periphery of the obtained laminated body can be performed on the extension of the operation of interposing the separator 13A between the electrodes. Therefore, the productivity is improved.

(Laminated lithium ion battery)
Hereinafter, referring to FIG. 2, FIG. 5 and FIG. 6, a rectangular laminated type according to an embodiment of the present invention will be described taking the case where the first electrode 11 is a negative electrode and the second electrode 12 is a positive electrode as an example. A lithium ion battery (hereinafter simply referred to as lithium ion battery 100) will be described. FIG. 5 is a perspective view schematically showing the appearance of the lithium ion battery 100. As shown in FIG. 6 is a cross-sectional view schematically showing the lithium ion battery 100 taken along line B-B of FIG. Although FIG. 6 shows the case where the lithium ion battery 100 includes the two electrode groups 10, the number of the electrode groups 10 is not limited to this, and may be one or more.

  In the lithium ion battery 100, the electrode group 10 is housed in a battery case 20 provided with a rectangular metal container 21 having a bottom and an opening and a lid 22 closing the opening of the metal container 21. One end of the negative electrode terminal 30 protrudes from one end of the lid 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 protruding from the lid 22 are each formed in a rivet shape, whereby the negative electrode terminal 30 and the positive electrode terminal 40 are fixed to the lid 22 via the washers 50A or 50B. . In addition, screw grooves (not shown) respectively engaged with the negative electrode terminal 30 and the positive electrode terminal 40, and the negative electrode current collector plate 31 and the positive electrode current collector plate (not shown) are provided and fixed to the lid 22. It is 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 electrode current collector plate (not shown). A current interrupting mechanism (not shown) such as a fuse may be connected to at least one of the connection path between the negative electrode terminal 30 and the negative electrode current collector plate 31 and the connection path between the positive electrode terminal 40 and the positive electrode current collector plate. .

  An insulating gasket 63 intervenes between the negative electrode current collector 31 and the lid 22 to insulate the negative electrode current collector 31 from the lid 22. Furthermore, an insulating container 80 may be disposed to cover the inner surface of the metal container 21. The insulating container 80 has a rectangular 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 in contact with 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 shift | offset | difference of stacked electrodes is prevented and the damage by the contact with the insulation container 80 of the electrode group 10 etc. is suppressed.

  The respective negative electrodes 11 constituting the electrode group 10 are electrically connected to the negative electrode current collector plate 31 through the negative electrode lead wires 32 respectively. Similarly, the positive electrode 12 is also electrically connected to the positive current collector plate via a positive electrode lead wire (not shown). The negative electrode lead wire 32 is joined to the negative electrode tab 111 b (see FIG. 2) of the negative electrode 11. The plurality of negative electrode lead wires 32 joined to the negative electrode tab 111 b of each negative electrode 11 constituting one electrode group 10 are electrically connected to each other by welding or the like, and then, for example, to the electrode group 10 of the negative electrode current collector plate 31. It is joined to the opposite surface. Similarly, the positive electrode lead wire is joined to the surface of the positive electrode current collector facing the electrode group 10. When accommodating several electrode groups 10 in the metal container 21, it arrange | positions so that one main surfaces which cross | intersect the lamination direction X of each electrode group 10 may oppose. The tabs of each electrode may be sufficiently long and welded to each other without using each lead wire, and then joined to each current collector plate.

  When assembling the lithium ion battery 100, first, while 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 interposed by the gaskets (61, 62 and 63), Fix each in the place of. Separately, the electrode group 10 is manufactured, each lead wire is joined to the electrode group 10, and the lead wires are joined to each other. The integrated leads are then joined to the current collectors fixed to the lid 22. Thereafter, the electrode group 10 is impregnated with the electrolytic solution, and the electrode group 10 in a state 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 of the electrolytic solution may be performed after the electrode group 10 is accommodated in the metal container 21.

(Battery case)
The materials of the metal container 21 and the metal container 21 constituting the battery case 20 are 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 appropriately set 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 also 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 sides of the negative electrode core material 111. The negative electrode core member 111 includes a negative electrode main portion 111 a and a negative electrode tab 111 b extending from a portion of the negative electrode main portion 111 a. The negative electrode active material layer 112 is not formed on at least a part of both surfaces of the negative electrode tab 111 b. When using the negative electrode lead wire 32, one end portion of the negative electrode lead wire 32 is joined to the negative electrode tab 111b by resistance welding or the like. The negative electrode active material layer 112 may be formed only on one side of the negative electrode main portion 111a.

  The negative electrode core material 111 is a porous or nonporous conductive substrate. As a material of the negative electrode core material 111, for example, a metal foil of stainless steel, nickel, copper, a copper alloy, aluminum or the like 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 contains a negative electrode active material as an essential component, and contains a binder, a conductive agent, and the like as an optional component. As the negative electrode active material, metal lithium, alloy (silicon alloy, tin alloy, etc.), carbon material (graphite, hard carbon, etc.), silicon compound, tin compound, lithium titanate compound, etc. are used. In forming the negative electrode active material layer 112, a negative electrode mixture containing the 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 portion 111a to dry the coating. Next, the dried coating film is rolled together with the negative electrode core member 111, whereby the negative electrode active material layer 112 having a predetermined thickness is formed. The thickness of the negative electrode active material layer 112 is not particularly limited, but 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 sides of the positive electrode core material 121. The positive electrode core member 121 includes a positive electrode main body portion 121 a and a positive electrode tab 121 b extending from a part of the positive electrode main body portion 121 a. The positive electrode active material layer 122 is not formed on both surfaces of the positive electrode tab 121 b. When the positive electrode lead wire is used, 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 side of the positive electrode main portion 121a.

  The positive electrode core material 121 is a porous or nonporous conductive substrate. As a 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 contains a positive electrode active material as an essential component, and contains a binder, a conductive agent and the like as an optional component. As the positive electrode active material of the lithium ion secondary batteries, lithium-containing composite oxide is preferably, for example, _{LiCoO 2, LiNiO 2, LiMn 2} O 4 is used. Manganese dioxide, fluorinated graphite, etc. are used as a positive electrode active material of a lithium ion primary battery. In forming the positive electrode active material layer 122, a positive electrode mixture containing the 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 portion 121a to dry the coating. Next, the dried coating is rolled together with the positive electrode core member 121, whereby the positive electrode active material layer 122 having a predetermined thickness is formed. The thickness of the positive electrode active material layer 122 is not particularly limited, but preferably 70 μm to 130 μm.

  As a binder which may be contained in the negative electrode active material layer 112 and / or the positive electrode active material layer 122, for example, fluorocarbon resin (polyvinylidene fluoride, polytetrafluoroethylene etc.), polyamide, polyimide, polyamide imide, polyacrylic acid, Styrene butadiene rubber etc. are mentioned. In addition, as a conductive agent that may be contained in the negative electrode active material layer 112 and / or the positive electrode active material layer 122, for example, graphite, carbon black, carbon fiber and the like can be mentioned.

(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 of the separator 13, for example, a 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, and more preferably 10 to 25 μm. The length of the longitudinal direction Y of the separator 13 is not particularly limited as long as it can be interposed between at least a stacked negative electrode and a positive electrode while being folded in a zigzag manner.

(Electrolytes)
The electrolyte may be in any form of liquid, gel or solid.
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 esters and the like are used. Examples of cyclic carbonates include propylene carbonate and ethylene carbonate. Examples of chain carbonates include diethyl carbonate, ethyl methyl carbonate and dimethyl carbonate. Examples of cyclic carboxylic acid esters include γ-butyrolactone and γ-valerolactone. Examples of lithium salts include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , and LiCF ₃ CO ₂ .

  The gelled electrolyte is usually composed of a polymer matrix and the above-mentioned solvent and lithium salt impregnated in the polymer matrix. The solid electrolyte is usually composed of a polymer matrix and the above 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 absorbs a liquid electrolyte to be gelled can be used. Specifically, a fluorine resin containing a vinylidene fluoride unit, an acrylic resin containing a (meth) acrylic acid and / or a (meth) acrylic acid ester unit, a polyether resin containing a polyalkylene oxide unit, and the like can be mentioned.

  As a fluorine resin containing vinylidene fluoride units, polyvinylidene fluoride (PVdF), a copolymer containing vinylidene fluoride (VdF) units and hexafluoropropylene (HFP) units (VdF-HFP), vinylidene fluoride (VdF) And copolymers containing trifluoroethylene (TFE) units.

(Anode 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 metal or nonmetal. Among them, metal foil is preferable. As metal foil, copper foil, copper alloy foil, nickel foil etc. are mentioned, for example. 25-200 micrometers is preferable and, as for the thickness of the negative electrode lead wire 32, 50-100 micrometers is more preferable.

(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 metal or nonmetal. Among them, metal foil is preferable. As a metal foil, aluminum foil, aluminum alloy foil, nickel, a nickel alloy, iron, stainless steel etc. are mentioned, for example. 25-200 micrometers is preferable and, as for the thickness of a positive electrode lead wire, 50-100 micrometers is more preferable.

(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 them, PFA is preferable in that it has low moisture permeability and can suppress the entry of water into the battery case.

(Porous sheet)
As the porous sheet 70, an insulating microporous thin film, a woven fabric or a 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 depending on 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, electric devices, machine tools, transport 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 devices include vacuum cleaners and video cameras. Machine tools include electric tools, robots, and the like. Transportation devices include electric vehicles, hybrid electric vehicles, plug-in HEVs, fuel cell vehicles and the like. Power storage devices include uninterruptible power supplies and the like.

100: lithium ion battery 10, 10A: electrode group,
11, 11A, 11B: first electrode (negative electrode)
111: negative electrode core material, 111a: negative electrode main portion, 111b: negative electrode tab 112: negative electrode active material layer 12, 12A: second electrode (positive electrode)
121: positive electrode core material, 121a: positive electrode main body, 121b: positive electrode tab 122: positive electrode active material layer 13, 13A: separator 13X: first end 13Y: second end 131: serpentine fold
131a: planar area, 131b: bending area 132: outer peripheral portion
132a: first area, 132b: second area, 132c: third area, 132d: fourth area 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: Washer 61, 62, 63: Gasket 70: Porous sheet 80: Insulation container

Claims (7)

A plurality of alternately stacked first electrodes and a plurality of second electrodes, and a serpentine folded portion so as to be interposed between the adjacent first electrodes and the second electrodes, and one short side A stack-type electrode group including a long separator having a first end portion and a second end portion which is the other short side,
The laminated lithium ion battery, wherein the zigzag portion does not cover at least one of a first main surface and a second main surface intersecting in the stacking direction of the electrode group. The zigzag portion does not cover at least the first main surface,
The separator further includes an outer periphery extending from the serpentine fold and having the first end,
The serpentine portion has the second end;
The second end is located on the second main surface side,
The boundary between the serpentine 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, and extends so as to surround one or more circumferences of the electrode group. Stacked lithium ion battery according to the description.   The stack type lithium ion battery according to claim 1, wherein the zigzag portion does not cover any of the first main surface and the second main surface.   The stack type lithium ion battery according to claim 3, wherein the first end and the second end are respectively disposed between the first main surface and the second main surface.   The layered lithium ion battery according to claim 1, further comprising a porous sheet surrounding the periphery of the electrode group by one or more turns.   The laminated 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 to 60%,
The stack-type lithium ion battery according to claim 6, wherein the porosity of the porous sheet is 40 to 80%.

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