Battery

Abstract

To suppress the occurrence of minute short circuits between the positive electrode sheet and the negative electrode sheet. [Solution] The outer surface of the wound body 30 is composed of the outermost part 60A-1 of the separator 60A, a part of the negative electrode sheet 40 facing the outermost part from the inner side is the outermost negative electrode part 40Mo, the part of the separator that is on the inner side of the outermost part is the inner side component 60A-3, 60B-3, a part of the negative electrode sheet facing the inner side component from the inner side is the inner negative electrode component 40IC, and at least at the upper end of one end of the wound body, the first gap GP1, which is the gap between the outermost part and the outermost negative electrode part, is larger than the second gap, which is the gap between the inner side component and the inner negative electrode component that are facing each other.

Description

Technical Field

[0001] The present disclosure relates to batteries.

Background Art

[0002] A secondary battery using an electrode body in which a positive electrode sheet including a positive electrode active material layer and a negative electrode sheet are laminated via a separator (separator sheet) and a non-aqueous electrolyte is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] After the first charge, a secondary battery may be subjected to a high-temperature aging treatment for dissolving or depositing metal foreign substances that may be mixed into the secondary battery during the manufacturing process. The "high-temperature aging treatment" means holding a secondary battery in a high SOC (State of Charge) state at a high temperature (for example, 60°C or higher) for a long time.

[0005] When a high-temperature aging treatment is performed on a secondary battery, there is a possibility that a micro short circuit may occur in the outermost layer region of the electrode body. The "micro short circuit" means that a metal component contained in the positive electrode active material layer elutes into the non-aqueous electrolyte, and a metal component is locally deposited on the surface of the negative electrode facing the site where the metal component of the positive electrode has eluted, and the positive electrode and the negative electrode are electrically connected.

[0006] For example, in a lithium-ion secondary battery, if the outermost part of the negative electrode body is located further out than the outermost part of the positive electrode sheet, lithium ions that have moved from the positive electrode sheet to the negative electrode sheet near the positive electrode current collector may move to the negative electrode active material layer at the outermost part of the negative electrode body via the non-aqueous electrolyte during high-temperature aging treatment. Furthermore, oxygen contained in the space within the case permeates the outermost separator and reacts with the lithium ions that have moved to the negative electrode active material layer at the outermost part of the negative electrode body, inducing the leaching of metal components from the positive electrode active material layer of the positive electrode sheet. This makes "micro-short circuits" more likely to occur during high-temperature aging treatment. When micro-short circuits occur, the self-discharge rate of the secondary battery increases.

[0007] This disclosure takes the above circumstances into consideration and aims to provide a battery that can suppress the occurrence of minute short circuits between the positive electrode sheet and the negative electrode sheet. [Means for solving the problem]

[0008] A battery according to a first aspect of the present disclosure comprises: a negative electrode body and a long strip-shaped negative electrode sheet having a negative electrode active material coated on both sides of the negative electrode body; a positive electrode body and a long strip-shaped positive electrode sheet having a positive electrode active material coated on both sides of the positive electrode body; a long strip-shaped separator located between the negative electrode sheet and the positive electrode sheet; a wound body formed by winding a laminate having the negative electrode sheet, the positive electrode sheet, and the separator around a predetermined axis; and a case for containing a non-aqueous electrolyte, wherein one end of the positive electrode body in the width direction is a positive electrode sheet where the positive electrode active material is not coated. The electrode current collector is configured such that the outer circumferential surface of the winding body is formed by the outermost circumferential portion of the separator, a portion of the negative electrode sheet facing the outermost circumferential portion from the inner circumferential side is the outermost negative electrode portion, the portion of the separator on the inner circumferential side to the outermost circumferential portion is the inner circumferential component, a portion of the negative electrode sheet facing the inner circumferential component from the inner circumferential side is the inner negative electrode component, and at least at the upper end of one end of the winding body, the first gap, which is the gap between the outermost circumferential portion and the outermost negative electrode portion, is larger than the second gap, which is the gap between the mutually opposing inner circumferential component and the inner negative electrode component.

[0009] In a battery according to a first aspect of this disclosure, a wound body is formed by winding a laminate having a long strip-shaped negative electrode sheet, a long strip-shaped positive electrode sheet, and a long strip-shaped separator around a predetermined axis, and a non-aqueous electrolyte is housed in a case. The negative electrode sheet has a negative electrode body and a negative electrode active material layer coated on both sides of the negative electrode body. The positive electrode sheet has a positive electrode body and a positive electrode active material layer coated on both sides of the positive electrode body. The separator is located between the negative electrode sheet and the positive electrode sheet. One end of the positive electrode body in the width direction is a positive electrode current collector portion where the positive electrode active material layer is not coated. The outer circumferential surface of the wound body is formed by the outermost circumferential portion of the separator, and a part of the negative electrode sheet facing the outermost circumferential portion from the inner circumferential side is the outermost circumferential portion of the negative electrode. Furthermore, the portion of the separator closer to the inner circumference than the outermost circumference is the inner circumference component, and a portion of the negative electrode sheet facing the inner circumference component from the inner circumference is the negative electrode inner circumference component. Ions may move from the outermost circumference of the positive electrode sheet to the negative electrode active material layer on the inner circumference of the outermost circumference of the negative electrode sheet. These ions may flow out into the non-aqueous electrolyte from one end of the negative electrode active material layer on the inner circumference at the outermost circumference of the negative electrode, and then move to the negative electrode active material layer on the outer circumference via the non-aqueous electrolyte. Furthermore, since there may be no non-aqueous electrolyte around the upper end of the winding body, the reaction between the ions that have moved to the negative electrode active material layer on the outer circumference and the oxygen contained in the space inside the case may be accelerated at the upper end of the outermost circumference of the negative electrode sheet. If such a reaction is accelerated, the elution of metal components from the positive electrode active material layer of the positive electrode sheet may be induced, making it easier for a minute short circuit to occur at one end of the upper end of the winding body.

[0010] Therefore, in the battery according to the first aspect of this disclosure, at least at the upper end of one end of the winding body, the first gap, which is the gap between the outermost part and the outermost part of the negative electrode, is made larger than the second gap, which is the gap between the opposing inner peripheral components and the inner peripheral component of the negative electrode. As a result, more non-aqueous electrolyte can be present in the first gap (than in the second gap). Therefore, even if oxygen in the upper space inside the case permeates from the outermost part of the separator to the inner peripheral side, contact of this oxygen with the negative electrode active material layer on the outer peripheral side of the upper end of the outermost part of the negative electrode is suppressed by the non-aqueous electrolyte in the first gap. This suppresses the leaching of metal components from the positive electrode active material layer of the positive electrode sheet, thereby suppressing the occurrence of minute short circuits.

[0011] The battery according to a second aspect of the present disclosure, in the configuration described in the first aspect, wherein the first gap is larger than the second gap only at the upper end of the winding body.

[0012] In the battery according to the second aspect of this disclosure, although there is no gap corresponding to the first gap at the lower end of the winding body, the amount of non-aqueous electrolyte at the bottom of the case is greater than at the top of the case, so there is little risk of oxygen permeating from the lower end of the outermost part to the inner side and coming into contact with the negative electrode active material layer on the outer side of the lower end of the outermost part of the negative electrode.

[0013] In the third aspect of the present disclosure, the battery, in the configuration described in the second aspect, has an opening only at its upper end.

[0014] In the battery according to the third aspect of this disclosure, the lower end of the wound body is easier to insert into the case. [Effects of the Invention]

[0015] According to this disclosure, a battery is provided that can suppress the occurrence of minute short circuits between a positive electrode sheet and a negative electrode sheet. [Brief explanation of the drawing]

[0016] [Figure 1] This is a perspective view showing the external appearance of a secondary battery according to an embodiment. [Figure 2]It is an exploded perspective view of a secondary battery according to an embodiment. [Figure 3] It is an exploded perspective view of a positive electrode sheet, a separator, and a negative electrode sheet. [Figure 4] It is a cross-sectional view obtained by cutting the wound body shown in FIG. 2 along the 4-4 arrow line. [Figure 5] It is a partially enlarged cross-sectional view obtained by cutting the wound body shown in FIG. 2 along the 5-5 arrow line. [Figure 6] It is a schematic side view of a winding device for a wound body. [Figure 7] It is a schematic diagram of a temporarily wound body. [Figure 8] It is a schematic diagram of a first pressing device and a temporarily wound body. [Figure 9] It is a schematic diagram of a second pressing device and a temporarily wound body. [Figure 10] It is a schematic diagram for explaining the direction of the force exerted from the second pressing device to the temporarily wound body. [Figure 11] It is a schematic diagram of a second pressing device and a deformed temporarily wound body. [Figure 12] It is a flowchart showing a method for manufacturing a secondary battery. [Figure 13] It is a schematic front view showing a part of the upper part of the secondary battery broken off. [Figure 14] It is a diagram showing the mechanism of a micro short circuit occurring in a region constituting the outermost layer of the wound body. [Figure 15] In a secondary battery having a configuration in which a wound body and a non-aqueous electrolyte are housed in a case, it is a graph showing the presence or absence of occurrence of a micro short circuit with respect to the amount of electrolyte. [Figure 16] It is a schematic diagram of a second pressing device and a temporarily wound body of the first modification example. [Figure 17] It is a schematic diagram of a second pressing device and a deformed temporarily wound body. [Figure 18] It is a schematic cross-sectional view of the upper end portion of the wound body of the second modification example. [Figure 19] It is a schematic side view of a winding device of the third modification example.

Mode for Carrying Out the Invention

[0017] Hereinafter, a battery according to the embodiment will be described with reference to the drawings. The battery according to the embodiment is a lithium-ion secondary battery that serves as a cell battery constituting a battery module used as an on-board power source for vehicles such as electric vehicles and hybrid vehicles. In each figure, arrow D indicates the longitudinal direction of the lithium-ion secondary battery 10 (hereinafter referred to as battery 10), arrow E indicates the depth direction of battery 10, and arrow F indicates the vertical direction of battery 10.

[0018] [Battery 10 configuration] As shown in Figures 1 and 2, the battery 10 includes a lid assembly 20, a wound body (electrode body) 30, an insulating bag 63, and a battery case (case) 70.

[0019] (Battery case 70) The battery case 70 is made of, for example, aluminum. An opening 71 is formed on the top surface of the battery case 70. That is, the battery case 70 has a rectangular parallelepiped shape with only the top surface open.

[0020] (Lid assembly 20) The lid assembly 20 comprises a lid member 21, a negative current collector terminal 22 as a current collector terminal, a positive current collector terminal 23 as a current collector terminal, a negative external terminal 24 as an external terminal, and a positive external terminal 25 as an external terminal.

[0021] <Lid member 21> The lid member 21 is made of, for example, aluminum and is a plate-shaped member extending in the longitudinal direction D. The lid member 21 is provided with a safety valve 21A and a cap 26 that closes the inlet 21B.

[0022] The safety valve 21A opens when the internal pressure of the battery case 70 reaches a predetermined pressure, releasing the gas generated inside the battery case 70.

[0023] The filling port 21B is a through-hole that penetrates the lid member 21 in the vertical direction. The filling port 21B is used when injecting a non-aqueous electrolyte 95 (described later) into the battery case 70. A cap 26 is attached to the filling port 21B in an airtight and liquid-tight manner, for example by laser welding.

[0024] <Negative current collection terminal 22 and negative external terminal 24> The negative electrode current collector terminal 22 and the negative electrode external terminal 24 are made of, for example, copper and are provided at the other end of the cover member 21 in the longitudinal direction D. The negative electrode current collector terminal 22 is a rectangular plate-shaped member with the depth direction E being the plate thickness direction. The negative electrode external terminal 24 is electrically connected to the negative electrode current collector terminal 22 and is exposed to the outside of the cover member 21.

[0025] <Positive current collection terminal 23 and positive external terminal 25> The positive electrode current collector terminal 23 and the positive electrode external terminal 25 are made of, for example, aluminum and are provided at one end of the cover member 21 in the longitudinal direction D. The positive electrode current collector terminal 23 is a rectangular plate-shaped member with the depth direction E being the plate thickness direction. The positive electrode external terminal 25 is electrically connected to the positive electrode current collector terminal 23 and is exposed to the outside of the cover member 21.

[0026] (Wound body 30) As shown in Figure 2, the winding body 30 includes a power generator 31, a negative electrode current collector 46, and a positive electrode current collector 54.

[0027] As shown in Figure 3, the wound body 30 is composed of a laminate 62 having a long, strip-shaped negative electrode sheet 40 as an electrode sheet, a long, strip-shaped positive electrode sheet 50 as an electrode sheet, and two long, strip-shaped separators 60A and 60B. The negative electrode sheet 40, the positive electrode sheet 50, and the separators 60A and 60B are flexible. As shown in Figures 3 and 4, the wound body 30 is constructed by winding the laminate 62 around a virtual axis IAX (see Figure 3) that extends in the width direction G of the negative electrode sheet 40, the positive electrode sheet 50, and the separators 60A and 60B. As shown in Figure 2, the wound body 30 has a flattened shape.

[0028] <Negative electrode sheet 40> As shown in Figure 3, the negative electrode sheet 40 comprises a long, strip-shaped negative electrode body 41, a first negative electrode active material layer (negative electrode active material layer) 42 coated on one side of the negative electrode body 41, and a second negative electrode active material layer (negative electrode active material layer) 43 coated on the other side of the negative electrode body 41. The negative electrode body 41 is made of, for example, copper foil. The first negative electrode active material layer 42 and the second negative electrode active material layer 43 have an inner circumferential negative electrode active material layer, which is the part on the side of the negative electrode body 41, and an outer circumferential negative electrode active material layer, which is the part on the opposite side of the negative electrode body 41. As shown in Figure 3, the first negative electrode active material layer 42 and the second negative electrode active material layer 43 are coated only on the areas of both sides of the negative electrode body 41, excluding the side opposite to one side G1. Therefore, a negative electrode current collector portion 46 is formed at the other end of the negative electrode body 41, where the first negative electrode active material layer 42 and the second negative electrode active material layer 43 are not coated.

[0029] The first negative electrode active material layer 42 and the second negative electrode active material layer 43 contain a negative electrode active material and a negative electrode binder. The negative electrode active material is a substance capable of intercalating and releasing lithium ions (for example, a carbon material (e.g., natural graphite, artificial graphite, etc.)). Examples include fluororesins (e.g., polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, etc.) and polyvinyl acetate.

[0030] <Positive electrode sheet 50> As shown in FIG. 3, the positive electrode sheet 50 includes a long strip-shaped positive electrode body 51, a first positive electrode active material layer (positive electrode active material layer) 52 coated on one surface of the positive electrode body 51, and a second positive electrode active material layer (positive electrode active material layer) 53 coated on the other surface of the positive electrode body 51. The first positive electrode active material layer 52 and the second positive electrode active material layer 53 have an inner peripheral side positive electrode active material layer which is a part on the side of the positive electrode body 51 and an outer peripheral side positive electrode active material layer which is a part on the side opposite to the positive electrode body 51. The positive electrode body 51 is made of, for example, an aluminum foil. As shown in FIG. 3, the first positive electrode active material layer 52 and the second positive electrode active material layer 53 are coated only on the region excluding the side portions on one side G1 of both surfaces of the positive electrode body 51. Therefore, a positive electrode current collector portion 54 where the first positive electrode active material layer 52 and the second positive electrode active material layer 53 are not coated is formed at the end of one side G1 of the positive electrode body 51.

[0031] The first positive electrode active material layer 52 and the second positive electrode active material layer 53 contain a positive electrode active material and a positive electrode binder. The positive electrode active material is a substance capable of occluding and releasing lithium ions. Examples of the positive electrode active material include lithium nickel-based oxides, lithium cobalt-based oxides (e.g., LiCoO2, etc.), and lithium manganese-based oxides (e.g., LiMn2O4). Examples of the lithium nickel-based oxides include LiCoO2, ternary lithium transition metal oxides, and solid solution type lithium-excess transition metal oxides. The ternary lithium transition metal oxide is represented by the general formula (A): Li(LiaMnxCoyNiz)O2 (where a, x, y, z in the formula (A) satisfy a + x + y + z ≒ 1 and xyz ≠ 0). The solid solution type lithium-excess transition metal oxide is represented by the general formula (B): xLi[Li1 / 3Mn2 / 3]O2·(1 - x)LiMeO2 (where Me is one or more transition metals in the formula (B) and x satisfies 0 < x ≦ 1). Examples of the positive electrode binder include fluororesins (e.g., polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, etc.), polyvinyl acetate, etc. The positive electrode active material layer may contain, if necessary, a conductive auxiliary agent (e.g., acetylene black, etc.), a thickening agent, a surfactant, a dispersant, a wetting agent, an antifoaming agent, etc.

[0032] <Separator 60A, 60B> The separators 60A and 60B are made of an insulating material such as polypropylene or polyethylene. Each of the separators 60A and 60B maintains the gap between the positive electrode sheet 50 and the negative electrode sheet 40 to prevent contact short circuits and holds the non-aqueous electrolyte 95. The separators 60A and 60B are, for example, porous resin plates.

[0033] As shown in Figures 3 and 5, the width dimension G of separators 60A and 60B is larger than that of the negative electrode sheet 40 and the positive electrode sheet 50. Separator 60B faces the first negative electrode active material layer 42 of the negative electrode sheet 40 and the second positive electrode active material layer 53 of the positive electrode sheet 50, while separator 60A faces the second negative electrode active material layer 43 of the negative electrode sheet 40. That is, separators 60A, negative electrode sheet 40, separator 60B, and positive electrode sheet 50 are stacked in this order, and the stacked body 62 is formed by the negative electrode sheet 40, positive electrode sheet 50, and separators 60A and 60B. Although not shown in the figures, one end G1 of the positive electrode current collector 54 of the positive electrode body 51 is located one side G1 from separators 60A and 60B. Similarly, the other end of the negative electrode current collector portion 46 of the negative electrode body 41 in the width direction G is located on the other side of the width direction G from the separators 60A and 60B.

[0034] The separator 60A, the negative electrode sheet 40, the separator 60B, and the positive electrode sheet 50 are formed into a laminate 62 by the winding device 80 shown in Figure 6. More specifically, the separator 60A, the negative electrode sheet 40, the separator 60B, and the positive electrode sheet 50 are formed into a substantially cylindrical wound body (not shown) by the winding device 80. The winding device 80 comprises driven rollers 81, 82, 83, 84, and a winding roller 85, all of which are parallel to each other. Furthermore, the winding device 80 comprises a drive device 86 and a control device 87. The negative electrode body 41 is wound around the driven roller 81, the positive electrode body 51 is wound around the driven roller 82, the separator 60B is wound around the driven roller 83, and the separator 60A is wound around the driven roller 84. The negative electrode body 41, the positive electrode body 51, the separator 60A, and the tip of the separator 60B are wound onto the winding roller 85 in the order of separator 60A, negative electrode sheet 40, separator 60B, and positive electrode sheet 50. A drive unit 86 is connected to the winding roller 85 via a power transmission mechanism (not shown). The drive unit 86 is, for example, an electric motor. Furthermore, a control device 87 is connected to the drive unit 86.

[0035] Furthermore, although not shown in the illustration, the winding device 80 has a pair of negative electrode coating devices and a negative electrode drying oven located directly above and directly below the negative electrode body 41. Furthermore, although not shown in the illustration, the winding device 80 has a pair of positive electrode coating devices and a positive electrode drying oven located downstream of the driven roller 82, directly above and directly below the positive electrode body 51. Furthermore, the winding device 80 has a cutting device.

[0036] The drive unit 86, the negative electrode coating device, the negative electrode drying oven, the positive electrode coating device, the positive electrode drying oven, and the cutting device are controlled by the control device 87.

[0037] As described later, the separator 60A, the negative electrode sheet 40, the separator 60B, and the positive electrode sheet 50 are processed by the winding device 80 to form a temporary winding body 65. Furthermore, the temporary winding body 65 is processed by the first press device 88 shown in Figure 8 and the second press device 89 shown in Figure 9 to form a winding body 30.

[0038] The first press device 88 shown in Figure 8 comprises a first support member 88A, a first movable member 88B, a first drive unit 88C, and a first control device 88D. The first support member 88A is a fixed body in the shape of a rectangular parallelepiped. The first movable member 88B is a member in the shape of a rectangular parallelepiped located directly above the first support member 88A. The first movable member 88B is movable relative to the first support member 88A in the vertical direction. The first movable member 88B is linked to the first drive unit 88C, and the first drive unit 88C is connected to the first control device 88D. The first drive unit 88C is an electric actuator that operates under the control of the first control device 88D.

[0039] The second press device 89 shown in Figure 9 comprises a second support member 89A, a second movable member 89B, a second drive unit 89C, and a second control device 89D. The second support member 89A is a metal plate and, as shown in Figure 9, is curved so as to be convex upwards when viewed from the front in its free state. That is, the front shape (cross-sectional shape) of the second support member 89A is approximately arc-shaped. The second movable member 89B is a metal plate and, as shown in Figure 9, is curved so as to be convex downwards when viewed from the front in its free state. That is, the front shape (cross-sectional shape) of the second movable member 89B is approximately arc-shaped. The second movable member 89B is relatively movable in the vertical direction relative to the second support member 89A. The second movable member 89B is linked to the second drive unit 89C, and the second drive unit 89C is connected to the second control device 89D. The second drive unit 89C is an electric actuator that operates under the control of the second control device 89D.

[0040] The control unit 87, the first control unit 88D, and the second control unit 89D are configured to include a CPU (Central Processing Unit: processor), ROM (Read Only Memory), RAM (Random Access Memory), storage, a communication interface (Interface), and an input / output interface (I / F). The CPU, ROM, RAM, storage, communication interface, and I / F are connected to each other via a bus so that they can communicate with one another.

[0041] The battery manufacturing system, including the winding device 80, the first pressing device 88, and the second pressing device 89, operates according to the steps in the flowchart of Figure 12.

[0042] In S10, when the drive unit 86 of the winding device 80 is started, the winding roller 85 rotates at a constant speed in the direction of arrow RD shown in Figure 6. As a result, the driven rollers 81, 82, 83, and 84 rotate, and the separator 60A, negative electrode sheet 40, separator 60B, and positive electrode sheet 50 are gradually wound up by the winding roller 85.

[0043] Furthermore, in S11, a first negative electrode active material layer 42 and a second negative electrode active material layer 43 are coated onto both sides of the negative electrode body 41 by a pair of negative electrode coating devices. The first negative electrode active material layer 42 and the second negative electrode active material layer 43 are then dried in a negative electrode drying oven.

[0044] Furthermore, in S12, downstream of the driven roller 82, a first positive electrode active material layer 52 and a second positive electrode active material layer 53 are coated on both sides of the positive electrode body 51 by a pair of positive electrode coating devices, and then the first positive electrode active material layer 52 and the second positive electrode active material layer 53 are dried in a positive electrode drying oven.

[0045] Furthermore, in S13, the separator 60A, the negative electrode sheet 40, the separator 60B, and the positive electrode sheet 50 are cut at their respective predetermined positions by a cutting device. As a result, the laminate 62 takes on a substantially cylindrical shape wound around the virtual axis IAX.

[0046] Next, in S14, the laminated body 62, which has a roughly cylindrical shape, is removed from the winding roller 85 (see Figure 7). Furthermore, as shown in Figure 7, the adhesive surface of one side of the adhesive tape 66 is brought into contact with the tip of the outermost part 60A-1 of the separator 60A and a different part of the outermost part 60A-1. As a result, the separator 60A, the negative electrode sheet 40, the separator 60B, and the positive electrode sheet 50 are integrated to form a roughly cylindrical temporary winding body 65 (see Figure 7). Note that in Figures 7 and 8 to 11, only the outermost part 60A-1 of the separator 60A and the adhesive tape 66 are depicted, not the entire temporary winding body 65.

[0047] Furthermore, in S15, the pressing process is carried out by the first press device 88 and the second press device 89.

[0048] In the pressing process, first, as shown in Figure 8, the temporary winding body 65 is placed on the upper surface of the first support member 88A of the first press device 88. Then, the first control device 88D activates the first drive device 88C, and the driving force of the first drive device 88C moves the first movable member 88B downward. As shown in Figure 8, the width of the first support member 88A and the first movable member 88B in a front view is narrower than the width (diameter) of the temporary winding body 65. Therefore, when the first movable member 88B approaches the first support member 88A, the central part of the temporary winding body 65 in the width direction is sandwiched vertically by the first support member 88A and the first movable member 88B, and both the upper and lower surfaces of the central part of the temporary winding body 65 in the width direction are concave. That is, the temporary winding body 65, which was approximately cylindrical in a front view, is deformed into the shape shown in Figure 9. In other words, the temporary winding body 65 has four protrusions 65A, 65B, 65C, and 65D when viewed from the front, and the central parts of the upper and lower sections are concave.

[0049] Next, as shown in Figure 9, the temporary winding body 65 is placed on the upper surface of the second support member 89A of the second press device 89. Furthermore, the second control device 89D activates the second drive device 89C, and the driving force of the second drive device 89C moves the second movable member 89B downward. As a result, as shown in Figure 9, one upper protrusion 65A and one lower protrusion 65C of the temporary winding body 65 are sandwiched from above and below by the second support member 89A and the second movable member 89B. In other words, the other upper protrusion 65B and the other lower protrusion 65D of the temporary winding body 65 are not sandwiched from above and below by the second support member 89A and the second movable member 89B. In this state, the second movable member 89B is moved further closer to the second support member 89A. As a result, strong pressure is applied to the protrusions 65A and 65C from the second support member 89A and the second movable member 89B, causing the entire temporary winding body 65 to deform into the front shape shown in Figure 11.

[0050] At this time, as shown in Figure 9, an upward force FU is exerted from the second support member 89A to the projection 65C, and a downward force FD is exerted from the second movable member 89B to the projection 65A. Now, referring to Figure 10, the effect of force FD on the projection 65A will be explained. As shown in Figure 10, the force FD exerted by the elastically deformed second movable member 89B on the projection 65A can be decomposed into component force FD1 and component force FD2. Component force FD1 is a component force in a direction perpendicular to the tangent to the contact point between the second movable member 89B and the projection 65A. The angle between component force FD1 and force FD is θ, and component force FD1 = FD × cosθ. On the other hand, component force FD2 is a component force in a direction approximately parallel to the above tangent, and component force FD2 = FD × sinθ. This component force FD2 causes the protrusion 65A and end 60A-2 of the outermost part 60A-1 of separator 60A to plastically deform so that they extend toward the other side as shown in Figure 9. Similarly, although not shown, a portion of the force FU exerted by the elastically deformed second support member 89A on the protrusion 65C becomes a component force FU2, which corresponds to component force FD2. Therefore, component force FU2 causes the protrusion 65C and end 60A-2 of the outermost part 60A-1 of separator 60A to plastically deform so that they extend toward the other side as shown in Figure 9. Furthermore, in reality, as shown in Figure 4, one end 60A-2 of the outermost part 60A-1 is in contact with one end 60B-2 of the outermost part 60B-1 of separator 60B (not shown in Figures 9 to 11). Therefore, the end portion 60A-2 of the separator 60B is plastically deformed by the deformed end portion 60A-2 due to forces FD and FU, causing it to extend in the same direction as the end portion 60A-2. Subsequently, when one end of the separators 60A and 60B is further pressed by the second support member 89A and the second movable member 89B, a gap is formed between the end 60B-2 and the outermost negative electrode portion 40Mo of the negative electrode sheet 40 (see Figure 4). Note that the dashed line in Figure 11, indicated by reference numeral 60A-2, represents one end of the outermost portion 60A-1 assuming that no plastic deformation occurred.

[0051] This results in a roughly flattened winding body 30 as shown in Figures 2 and 11. As shown in Figure 2, the positive electrode current collector 54 is wound to form one end G1 of the winding body 30, and the negative electrode current collector 46 is wound to form the other end of the winding body 30. Furthermore, the region between the negative electrode current collector 46 and the positive electrode current collector 54 of the winding body 30 is the power generator 31. The power generator 31 has the function of storing electrical energy from the battery 10.

[0052] Furthermore, in S16, the battery manufacturing system performs a terminal welding process. As a result, the lower end of the negative electrode current collector terminal 22 is connected by resistance welding to the vertical center of the negative electrode current collector section 46 of the winding body 30, and the lower end of the positive electrode current collector terminal 23 is connected by ultrasonic welding to the vertical center of the positive electrode current collector section 54. Therefore, as shown in Figure 2, the other end of the winding body 30 is deformed and the other end of the winding body 30 is filled with foil. Also, the end of one side G1 of the winding body 30 is deformed and the end of one side G1 of the winding body 30 is filled with foil. Furthermore, the battery manufacturing system houses the negative electrode current collector terminal 22, the positive electrode current collector terminal 23, the integrated winding body 30, and the insulating bag 63 in the internal space of the battery case 70 through the opening 71. Furthermore, the lid member 21 is attached to the upper end of the battery case 70, for example by laser welding, so as to close the opening 71. Furthermore, a cell drying process is then performed by the battery manufacturing system. The insulating bag 63 houses the wound body 30, thereby electrically insulating the wound body 30 from the lid member 21 and the battery case 70.

[0053] As shown in Figure 4, the ends 60A-2 and 60B-2 of the separators 60A and 60B, which are plastically deformed to one side by the second press device 89 in Figure 9, constitute a part of the upper end 30UP of the winding body 30. Here, the upper end 30UP of the winding body 30 is the upper part of the winding body 30, as shown in Figure 4, and the cross-sectional shape of its outer surface is R-shaped.

[0054] Furthermore, in S17, the battery manufacturing system performs a liquid injection and sealing process. In the liquid injection and sealing process, a non-aqueous electrolyte 95 is injected through an injection port 21B formed in the lid member 21, and a cap 26 is attached to the injection port 21B, for example, by laser welding. This completes the battery 10 shown in Figure 1.

[0055] The non-aqueous electrolyte 95 of this embodiment contains an electrolyte and a non-aqueous solvent. Examples of electrolytes include lithium salts containing fluorine (e.g., lithium hexafluoride phosphate, lithium tetrafluoride borate, etc.) and lithium salts not containing fluorine (e.g., lithium perchlorate, lithium aluminate tetrachloride, etc.). Examples of non-aqueous solvents include cyclic carbonates (e.g., ethylene carbonate, etc.) and chain carbonates (e.g., dimethyl carbonate, ethyl methyl carbonate, etc.). The non-aqueous electrolyte 95 may further contain additives (e.g., lithium bisoxalate borate, etc.).

[0056] Furthermore, in S18, an activation process is carried out by the battery manufacturing system. In the activation process, the battery 10 is initially charged, and then a high-temperature aging treatment is performed, in which it is stored at a high temperature for a certain period of time to dissolve metallic foreign matter and stabilize the SEI (Solid Electrolyte Interphase) coating.

[0057] (Mechanism of action and effect) The operation and effects of this embodiment will be described below.

[0058] Incidentally, when a high-temperature aging treatment is performed on a battery 10 in which oxygen contained in the space inside the battery case 70 is likely to come into contact with the second negative electrode active material layer 43, which is the outermost negative electrode active material layer of the wound body 30, a minute short circuit may occur near the positive electrode current collector 54. The mechanism of such a minute short circuit will be explained below with reference to Figure 14.

[0059] Figure 14 shows the outermost layer of one end G1 of the wound body 30 of the comparative example battery 100. The comparative example battery 100 has the same structure as the embodiment battery 10 except that the wound body 30 does not have plastically deformed ends 60A-2 and 60B-2. Therefore, the same reference numerals are used for components of battery 100 that are the same as those of battery 10, and detailed explanations are omitted.

[0060] In the region constituting the outermost layer of the winding body 30 of the battery 100, one end of the separator 60A (60B) constituting the outer surface of the winding body 30 on one side G1 contacts the portion of the second negative electrode active material layer 43 of the negative electrode sheet 40 that corresponds to the non-opposing region 41St, and also covers the negative electrode sheet 40 from one side G1. Here, the non-opposing region 41St is a part of the negative electrode sheet 40 that is located on one side G1 of the positive electrode sheet 50, and is located on one side G1 of the end of one side G1. Thus, in the battery 100, the outermost part of the negative electrode sheet 40 is located on the inner side of the outermost region of the separator 60A. This outermost part of the negative electrode sheet 40 is called the outermost negative electrode portion 40Mo. Therefore, the portion of the positive electrode sheet 50 that is opposite the outermost negative electrode portion 40Mo contributes to the battery reaction of the battery 100, making it possible to increase the energy density. On the other hand, in battery 100, as shown in Figure 4, when oxygen (see symbol O2) contained in the upper space inside the battery case 70 permeates through the ends 60A-2 and 60B-2 of the separator 60A (60B), the oxygen O2 is likely to come into contact with the second negative electrode active material layer 43 at the upper end of the outermost part 40Mo of the negative electrode.

[0061] In the high-temperature aging process, a battery 100 with a high SOC (e.g., 3.97V) is used. As shown in Figure 14, in a battery 100 with a high SOC, the first negative electrode active material layer 42 on the inner circumference side that constitutes the outermost negative electrode portion 40Mo of the negative electrode sheet 40 contains many lithium ions in the region facing the second positive electrode active material layer 53. On the other hand, it is thought that there are almost no lithium ions in the non-facing region 41St of the first negative electrode active material layer 42 in the outermost negative electrode portion 40Mo that does not face the second positive electrode active material layer 53. Furthermore, it is thought that there are almost no lithium ions in the outermost second negative electrode active material layer 43 that constitutes the outermost negative electrode portion 40Mo.

[0062] As shown in Figure 14, when a high-temperature aging treatment is performed on a battery 100 with a high SOC, lithium ions 90 move from the second positive electrode active material layer 53, which constitutes the outermost region of the positive electrode sheet 50, to the first negative electrode active material layer 42, which is the outermost region 40Mo of the negative electrode.

[0063] In the outermost part 40Mo of the negative electrode, due to the difference in lithium ion concentration, lithium ions 90 present in the region of the first negative electrode active material layer 42 facing the second positive electrode active material layer 53 move to the non-facing region 41St of the first negative electrode active material layer 42 that does not face the second positive electrode active material layer 53 (direction of arrow D1 in Figure 14).

[0064] Lithium ions 90 that have moved to a portion of the non-facing region 41St of the first negative electrode active material layer 42 flow out from the end face ES of one side G1 of the first negative electrode active material layer 42 into the non-aqueous electrolyte 95 present in the region 30S between the end face ES and the separator 60A, due to the difference in lithium ion concentration 90. They then move to the end face ES of the second negative electrode active material layer 43 at the outermost part 40Mo of the negative electrode (direction of arrow D2). At this time, if a part of the outermost part 60A-1 of the separator 60A (part 60AS) comes into contact with the end face 40ES of the negative electrode sheet 40, a flow path for lithium ions 90 to move to the second negative electrode active material layer 43 is easily formed, mediated by the non-aqueous electrolyte 95 held in the part 60AS facing the end face ES of the separator 60A.

[0065] When oxygen contained within the battery case 70 permeates through the separator 60A, this oxygen comes into contact with the second negative electrode active material layer 43 at the outermost periphery 40Mo of the negative electrode. As a result, lithium ions 90 that have moved to the second negative electrode active material layer 43 at the outermost periphery 40Mo of the negative electrode react with oxygen, forming a film 45 on the surface of the second negative electrode active material layer 43. In other words, lithium ions 90 that have moved to the outermost second negative electrode active material layer 43 are consumed by reacting with oxygen. Due to the consumption of lithium ions 90 caused by the formation of this film 45, the movement of lithium ions 90 to the non-opposing region 41St in the first negative electrode active material layer 42 is accelerated. As shown in Figure 4, at the upper end of the wound body 30, the ends 60A-2 and 60B-2 of the separators 60A and 60B come into contact with each other. Therefore, when oxygen O2 located in the upper space inside the battery case 70 permeates through the ends 60A-2 and 60B-2, the oxygen O2 comes into contact with the second negative electrode active material layer 43 (not shown in Figure 4) at the upper end of the outermost part 40Mo of the negative electrode.

[0066] As lithium ions 90 move in this manner, the potential of the edge of the first negative electrode active material layer 42 adjacent to the non-opposing region 41St in the region facing the positive electrode sheet 50 locally increases. Furthermore, due to local potential equalization, the potential of the edge of one side G1 of the second positive electrode active material layer 53 (the part facing the edge adjacent to the non-opposing region 41St of the first negative electrode active material layer 42) increases. In other words, the outermost region of the positive electrode sheet 50 becomes locally overvoltage (for example, 4.3V or higher).

[0067] When an overvoltage occurs in the positive electrode sheet 50, the crystal structure of the second positive electrode active material layer 53 collapses, and the metal component 44 contained in the second positive electrode active material layer 53 becomes more easily eluted into the non-aqueous electrolyte 95, as shown in Figure 14. The metal component 44 eluted into the non-aqueous electrolyte 95 is more likely to precipitate on the surface of the portion of the first negative electrode active material layer 42 facing the second positive electrode active material layer 53. As a result, metal deposits 48 that electrically connect the positive electrode sheet 50 and the negative electrode sheet 40 are formed on the surface of the first negative electrode active material layer 42. Consequently, a minute short circuit occurs between the first negative electrode active material layer 42 and the second positive electrode active material layer 53.

[0068] To demonstrate the mechanism of such minute short circuits, the correlation between the presence or absence of a minute short circuit near the positive electrode current collector 54 in the outermost layer of the wound body 30 of the comparative example battery 100 and the amount of non-aqueous electrolyte 95 in the battery case 70 was investigated.

[0069] The horizontal axis of Figure 15 shows the amount of non-aqueous electrolyte 95 in the battery case 70, and the vertical axis shows the presence or absence of a minute short circuit at the upper end 30UP of the wound body 30. The amount of non-aqueous electrolyte 95 on the horizontal axis is based on Comparative Example 1, in which a minute short circuit occurred near the positive electrode current collector 54 in the region constituting the outermost layer of the wound body 30. The amount of electrolyte in Comparative Example 1 is set to 100[%], and the amount of electrolyte in each comparative example is shown as an index. In Comparative Example 1, where the amount of non-aqueous electrolyte 95 is set to 100[%], a minute short circuit occurred near the positive electrode current collector 54 in the region constituting the outermost layer of the wound body 30.

[0070] On the other hand, in Comparative Example 2, where the amount of non-aqueous electrolyte 95 was set to 74%, no minute short circuits occurred. This is thought to be because, in Comparative Example 2, where the amount of non-aqueous electrolyte 95 in the battery case 70 is less than in Comparative Example 1, the movement of lithium ions 90 mediated by the non-aqueous electrolyte 95 (arrow D2 in Figure 13) was suppressed at the outermost negative electrode portion 40Mo of the negative electrode sheet 40. In other words, in Comparative Example 2, the amount of lithium ions 90 moving from the first negative electrode active material layer 42 to the second negative electrode active material layer 43 is small, so the outermost region of the positive electrode sheet 50 does not become overvoltage, and therefore no minute short circuits occur.

[0071] Furthermore, even in Comparative Example 3, where the amount of non-aqueous electrolyte 95 was set to 140%, no minute short circuits occurred. This is thought to be because, in Comparative Example 3, where the amount of non-aqueous electrolyte 95 in the battery case 70 is larger than in Comparative Example 1, the non-aqueous electrolyte 95 is injected up to the upper region of the battery case 70, thus suppressing contact between the upper end portion 30UP of the wound body 30 (outermost part of the negative electrode 40Mo) and the air contained in the space inside the battery case 70. In other words, in Comparative Example 3, the amount of oxygen that permeates through the outermost part 60A-1 (60B-1) of the separator 60A (60B) is small, so the amount of oxygen that contacts the second negative electrode active material layer 43 at the upper end portion of the outermost part of the negative electrode 40Mo is small. Therefore, the consumption of lithium ions 90 by oxygen inside the battery case 70 is suppressed, and no minute short circuits occur.

[0072] As shown in Figure 15, the verification results for Comparative Examples 1 to 3 all demonstrate the effectiveness of the micro-short circuit generation mechanism shown in Figure 14. In other words, it has become clear that if, by some means, oxygen located in the upper space inside the battery case 70 permeates the ends 60A-2 and 60B-2 to the inner circumference side, and this oxygen is prevented from contacting the second negative electrode active material layer 43 at the upper end of the outermost part 40Mo of the negative electrode, the generation of micro-short circuits can be suppressed. For this reason, in this embodiment, as shown in Figures 4 and 13, the winding body 30 is provided inside the battery case 70 such that the ends 60A-2 and 60B-2 of the separators 60A and 60B constitute the upper end of the winding body 30. As shown in Figure 13, in this case, the upper end of the winding body 30 is located below the lid assembly 20 (lid member 21).

[0073] As shown in Figure 4, the parts of separators 60A and 60B located inward from the outermost parts 60A-1 and 60B-1 are defined as inner-circumferential components 60A-3 and 60B-3. The number of inner-circumferential components 60A-3 and 60B-3 varies depending on the number of turns of separators 60A and 60B. For example, in the example in Figure 4, separators 60A and 60B have 5 turns, there are 4 inner-circumferential components 60A-3 and 5 inner-circumferential components 60B-3.

[0074] Furthermore, as shown in Figure 4, the portion of the negative electrode sheet 40 that faces each inner circumference component 60A-3, 60B-3 from the inner circumference side is defined as the negative electrode inner circumference component 40IC. The number of negative electrode inner circumference components 40IC varies depending on the number of turns of the negative electrode sheet 40. For example, in the example in Figure 4, the number of turns of the negative electrode sheet 40 is 4, and the number of negative electrode inner circumference components 40IC is 3.

[0075] Furthermore, as shown in Figure 4, the gap between the end portion 60B-2 and the upper end portion of the outermost negative electrode portion 40Mo facing the end portion 60B-2 from the inner circumference side is defined as the first gap GP1. The cross-sectional shape of the first gap GP1 is substantially arc-shaped. Furthermore, the gaps between each inner circumference component 60A-3 and each negative electrode inner circumference component 40IC that face each other in the radial direction of the wound body 30, and the gaps between each inner circumference component 60B-3 and each negative electrode inner circumference component 40IC that face each other in the radial direction of the wound body 30 are defined as the second gap GP2. In the wound body 30 of this embodiment, the multiple second gaps GP2 formed are substantially zero. That is, the first gap GP1 is larger than the second gap GP2.

[0076] Here, for example, we assume that the liquid level (top surface) of the non-aqueous electrolyte 95 injected into the battery case 70 is substantially the same as the upper end of the wound body 30. In other words, we assume that oxygen-containing air exists in the upper space 70US (see Figure 13), which is the space above the upper end of the wound body 30 inside the battery case 70. In this case, the oxygen in the upper space 70US permeates the ends 60A-2 and 60B-2 of 60A and 60B toward the inner circumference. Therefore, this oxygen may come into contact with the second negative electrode active material layer 43 at the upper end of the outermost outermost part 40Mo of the negative electrode. That is, in the non-facing region 41St of the negative electrode sheet 40 included in the upper end 30UP, the reaction between the lithium ions 90 that have moved to the outermost second negative electrode active material layer 43 and the oxygen contained in the space inside the battery case 70 may be accelerated.

[0077] However, in the battery 10 of this embodiment, the first gap GP1 between the end portion 60B-2 and the upper end portion of the outermost negative electrode 40Mo facing the end portion 60B-2 from the inner circumference side is larger than the second gap GP2. Therefore, more non-aqueous electrolyte 95 is injected into the first gap GP1 (than into the second gap GP2). As a result, even if oxygen in the upper space 70US permeates the ends 60A-2 and 60B-2 of the separators 60A and 60B to the inner circumference side, contact of this oxygen with the second negative electrode active material layer 43 at the upper end portion of the outermost negative electrode 40Mo is suppressed by the non-aqueous electrolyte 95 in the first gap GP1. This suppresses the dissolution of metal components 44 contained in the second positive electrode active material layer 53 into the non-aqueous electrolyte 95, thereby suppressing the occurrence of the above-mentioned minute short circuits.

[0078] Furthermore, while a first gap GP1 (ends 60A-2, 60B-2) is provided at the upper end 30UP of the winding body 30, a first gap GP1 (corresponding to the parts of ends 60A-2, 60B-2) is not provided at the lower end of the winding body 30. Therefore, the depth dimension E of the lower end of the winding body 30 is smaller than the depth dimension E of the upper end 30UP. As a result, the lower end of the winding body 30 is easier to insert into the battery case 70 through the opening 71 compared to the case where a first gap GP1 is formed at the lower end of the winding body 30. In other words, the assembly of the battery 10 is better compared to the case where a first gap GP1 is formed at the lower end of the winding body 30.

[0079] Furthermore, although there is no gap corresponding to the first gap GP1 at the lower end of the wound body 30, the amount of non-aqueous electrolyte 95 at the lower part of the battery case 70 is greater than at the upper end of the battery case 70. Therefore, there is little risk of oxygen permeating the lower ends of the outermost parts 60A-1 and 60B-1 of the separators 60A and 60B to the inner side and coming into contact with the second negative electrode active material layer 43 at the lower end of the outermost part 40Mo of the negative electrode.

[0080] Furthermore, if a first gap GP1 is also provided at the lower end of the wound body 30, the non-aqueous electrolyte 95 in the battery case 70 will flow into this first gap GP1 at the lower end. In other words, this may reduce the amount of non-aqueous electrolyte 95 that flows into the first gap GP1 at the upper end 30UP. However, in this embodiment, there is no such risk.

[0081] Furthermore, as shown in Figure 4, a portion of the upper end of the outermost part of the positive electrode sheet 50 is located on the inner side of a portion of the outermost negative electrode portion 40Mo of the negative electrode sheet 40 included in the upper end portion 30UP (the right-hand region in Figure 4), while the upper end of the outermost part of the positive electrode sheet 50 is not located on the inner side of the remaining portion of the outermost negative electrode portion 40Mo included in the upper end portion 30UP (the left-hand region in Figure 4). Therefore, compared to the case where the upper end of the outermost part of the positive electrode sheet 50 is located on the inner side of the entire region included in the upper end portion 30UP of the outermost negative electrode portion 40Mo, minute short circuits are less likely to occur between the outermost negative electrode portion 40Mo and the outermost part of the positive electrode sheet 50.

[0082] Although a battery and a method for manufacturing a battery according to the embodiment have been described above, the battery and the method for manufacturing a battery can be modified as appropriate without departing from the spirit of the present invention.

[0083] For example, instead of the second press device 89, the first modified second press device 92 shown in Figure 16 may be used to manufacture the temporary winding body 65. The second press device 92 includes a second support member 92A, a second movable member 92B, a second drive device 89C (not shown), and a second control device 89D (not shown). The second support member 92A is a metal plate and is curved so as to be convex upwards when viewed from the front in its free state, as shown in Figure 16. However, the curvature of the second support member 92A is different from that of the second support member 89A. The second movable member 92B is a metal plate and is curved so as to be convex downwards when viewed from the front in its free state, as shown in Figure 16. However, the curvature of the second movable member 92B is different from that of the second movable member 89B.

[0084] As shown in Figure 16, the temporary winding body 65 is placed on the upper surface of the second support member 92A of the second press device 92. Furthermore, the second control device 89D activates the second drive device 89C, and the driving force of the second drive device 89C moves the second movable member 92B downward. As a result, as shown in Figure 16, one upper projection 65A and one lower projection 65C of the temporary winding body 65 are sandwiched from above and below by the second support member 92A and the second movable member 92B, and the other upper projection 65B and the other lower projection 65D are sandwiched from above and below by the second support member 92A and the second movable member 92B. In this state, the second movable member 92B is moved even closer to the second support member 92A. As a result, strong pressure is applied from the second support member 92A and the second movable member 92B to the protrusions 65A, 65B, 65C, and 65D, causing the entire temporary winding body 65 to deform into the front shape shown in Figure 16. At this time, as shown in Figure 16, an upward force FU is applied from the second support member 92A to the protrusions 65C and 65D, and a downward force FD is applied from the second movable member 92B to the protrusions 65A and 65B. In this case as well, a leftward component force FU2 is applied from the second support member 92A to the protrusion 65C, and a leftward component force FD2 is applied from the second movable member 92B to the protrusion 65A. Furthermore, a rightward component force FU2 is applied from the second support member 92A to the protrusion 65D, and a rightward component force FD2 is applied from the second movable member 92B to the protrusion 65B. Therefore, as shown in Figure 17, the right-side force components FU2 and FD2 cause plastic deformation of one end 60A-2 (right side in Figure 16) of the outermost part 60A-1 (60B-1) of separator 60A (60B) so that it extends to the other side, and the left-side force components FU2 and FD2 cause plastic deformation of the other end 60A-2 (60B-2) (left side in Figure 16) of the outermost part 60A-1 of separator 60A (60B) so that it extends to the other side. Subsequently, when one end and the other end of the separators 60A and 60B are further pressed by the second support member 89A and the second movable member 89B, a gap is formed between one end 60B-2 of the outermost outermost portion 60B-1 and the outermost negative electrode portion 40Mo of the negative electrode sheet 40, and a gap is also formed between the other end of the outermost outermost portion 60B-1 and the outermost negative electrode portion 40Mo of the negative electrode sheet 40. In other words, in this modified example, a first gap GP1 is formed at the upper end 30UP and the lower end of the wound body 30.

[0085] Furthermore, as shown in the second modified example in Figure 18, the winding body 30 may be configured such that the negative electrode sheet 40 is positioned between the separator 60A and the separator 60B at the upper end portion 30UP. In this case, a first gap GP1 is formed between the end portion 60A-2 of the outermost outermost portion 60A-1 of the separator 60A and the outermost negative electrode portion 40Mo of the negative electrode sheet 40.

[0086] Furthermore, as shown in the third modified example in Figure 19, the winding device 80A may include a first driven roller 97 that rotatably contacts the upper surface of the separator 60A between the driven roller 84 and the winding roller 85, and a second driven roller 98 that rotatably contacts the lower surface of the separator 60A. Although not shown in the figure, the winding device 80A includes driven rollers 81, 82, 83, a drive unit 86, and a control unit 87. In addition, the winding device 80A allows the first driven roller 97 to move between an initial position shown by a solid line and a tension-applied position shown by a dashed line. Furthermore, the winding device 80A includes a moving actuator for moving the first driven roller 97. This moving actuator is controlled by the control unit 87. In this third modified example, at a predetermined timing while the separator 60A, negative electrode sheet 40, separator 60B, and positive electrode sheet 50 are being wound by the winding roller 85, a moving actuator controlled by the control device 87 moves the first driven roller 97 from its initial position to a tension-applying position for a very short time, and then immediately returns the first driven roller 97 to its initial position. This causes a portion of the separator 60A to be plastically deformed so that it is stretched. Therefore, when the temporary wound body 65 (not shown) produced by this winding device 80A is clamped by a press device (not shown), a wound body 30 identical to that shown in Figure 18 is obtained.

[0087] The winding device 80A may also include a first driven roller 97 that rotatably contacts the upper surface of the separator 60B between the driven roller 83 and the winding roller 85, and a second driven roller 98 that rotatably contacts the lower surface of the separator 60B. When the temporary winding body 65 (not shown) produced by this winding device 80A is clamped by a press device (not shown), a winding body 30 identical to that shown in Figure 4 is obtained.

[0088] Furthermore, by reducing the rotational speed of the winding roller 85 of the winding device 80 in the embodiment for a very short time, it is possible to stretch (loosen) a portion of the separators 60A and 60B compared to other parts. When the temporary winding body 65 (not shown) manufactured by this method is sandwiched by a press device (not shown), the same winding body 30 as shown in Figure 4 is obtained.

[0089] The upper end portion 30UP of the winding body 30 may be a region narrower than the region shown in Figure 4. For example, as shown in upper end portion 30UP-X in Figure 4, the upper end portion of the winding body 30 may be the region between the portion above the lower end of the part where the upper cross-sectional shape of the winding body 30 is R-shaped and the upper end of the winding body 30. [Explanation of Symbols]

[0090] 10. Lithium-ion rechargeable battery (battery) 30 Wound body (electrode body) 40 Negative electrode sheets 40Mo outermost part of the negative electrode 40IC negative electrode inner circumferential side component 41 Negative electrode body 42 First negative electrode active material layer (negative electrode active material layer) 43 Second negative electrode active material layer (negative electrode active material layer) 50 Positive Electrode Sheets 51 Positive electrode body 52 First positive electrode active material layer (positive electrode active material layer) 53 Second positive electrode active material layer (positive electrode active material layer) 54 Positive electrode current collector 60A Separator 60A-1 Outermost part 60A-3 Inner circumference component 60B Separator 60B-1 Outermost part 60B-3 Inner peripheral side component 62-layer structure 70 Battery Case (Case) 71 Opening 95 Nonaqueous electrolyte GP1 First gap

Claims

1. A long, strip-shaped negative electrode sheet having a negative electrode body and a negative electrode active material coated on both sides of the negative electrode body, A positive electrode sheet having a positive electrode body and a positive electrode active material coated on both sides of the positive electrode body, A long, strip-shaped separator located between the negative electrode sheet and the positive electrode sheet, A wound body formed by winding a laminate having the negative electrode sheet, the positive electrode sheet, and the separator around a predetermined axis, and a case for containing a non-aqueous electrolyte, Equipped with, One end of the positive electrode body in the width direction is a positive electrode current collector portion to which the positive electrode active material is not coated. The outer circumferential surface of the winding body is formed by the outermost circumferential portion of the separator, A portion of the negative electrode sheet that faces the outermost outer portion from the inner side is the outermost negative electrode portion. The portion of the separator located on the inner side of the outermost part is the inner side component. A portion of the negative electrode sheet that faces the inner circumferential component from the inner circumferential side is the negative electrode inner circumferential component. A battery in which, at least at the upper end of one end of the wound body, the first gap, which is the gap between the outermost part and the outermost part of the negative electrode, is larger than the second gap, which is the gap between the opposing inner peripheral components and the inner peripheral component of the negative electrode.

2. The battery according to claim 1, wherein the first gap is larger than the second gap only at the upper end of the winding body.

3. The battery according to claim 2, wherein the case has an opening only at its upper end.

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