Power storage cell

Abstract

To reduce stress concentration at the end of the winding of the wound electrode body.SOLUTION: A power storage cell includes a cell case, a wound electrode body, a fixing member, and an electrolyte. The cell case houses the wound electrode body, the fixing member, and the electrolyte. The wound electrode body is formed by winding an electrode and a separator. The fixing member fixes an end of the wound electrode body in the winding direction. The fixing member includes an adhesive component. The adhesive component is soluble in the electrolyte.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an energy storage cell. [Background technology]

[0002] WO 2019 / 064806 discloses a tape for fixing the end of a wound electrode body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 064806 Summary of the Invention [Problem to be solved by the invention]

[0004] A wound electrode body is formed by winding the electrodes and separator. To insert the wound electrode body into a cell case, the end of the wound electrode body can be fixed, for example, with adhesive tape. For example, when the energy storage cell is charged, the electrodes may expand. Because the end of the wound electrode body is fixed, stress due to the expansion of the electrodes may be concentrated at the end of the winding.

[0005] An object of the present disclosure is to alleviate stress concentration at the winding end portion of a wound electrode body. [Means for solving the problem]

[0006] The technical configuration and effects of the present disclosure will be described below. However, the mechanism of action includes speculation. The mechanism of action does not limit the technical scope of the present disclosure.

[0007] 1. The energy storage cell includes a cell case, a wound electrode body, a fixing member, and an electrolyte. The cell case houses the wound electrode body, the fixing member, and the electrolyte. The wound electrode body is formed by winding an electrode and a separator. The fixing member fixes the end of the winding direction of the wound electrode body. The fixing member includes an adhesive component. The adhesive component is soluble in the electrolyte.

[0008] The fixing member includes an adhesive component. The adhesive component fixes the end of the winding, allowing the wound electrode body to be smoothly inserted into the cell case. After insertion into the cell case, the adhesive component dissolves in the electrolyte, reducing the fixing force of the end of the winding. This reduction in fixing force is expected to alleviate stress concentration at the end of the winding.

[0009] 2. The storage cell according to the above item "1" may include, for example, the following configuration: The fixing member further includes a substrate, and the substrate supports the adhesive component.

[0010] By including a base material in the fixing member, it is expected that the strength will be improved. The improved strength is expected to enable the fixing member to maintain a predetermined shape until, for example, the wound electrode body is inserted into the cell case.

[0011] 3. The energy storage cell described in "1" above may include, for example, the following configuration: At least a part of the fixing member is disposed on the inner circumferential side of the outermost layer of the wound electrode body in the radial direction of the wound electrode body. In the winding direction of the wound electrode body, the center part of the fixing member is located inside the winding end part of the wound electrode body.

[0012] The fixing member may be arranged, for example, so as to straddle the end of the winding. For example, if the fixing member is arranged on the outer periphery of the outermost layer, a step may be formed on the outer surface of the wound electrode body due to the thickness of the fixing member. Stress concentration may also occur at the step. By arranging the fixing member on the inner periphery of the outermost layer, it is expected that the step will be reduced. Furthermore, the amount of the fixing member protruding from the end of the winding may be reduced.

[0013] 4. The energy storage cell described in "2" above may include, for example, the following configuration: In the radial direction of the wound electrode body, at least a part of the fixing member is disposed on the inner circumferential side of the outermost layer of the wound electrode body; In the winding direction of the wound electrode body, the base material of the fixing member is located inside the winding end portion of the wound electrode body; and The base material of the fixing member is not located outside the winding end portion of the wound electrode body.

[0014] Since the base material of the fixing member does not protrude outward from the winding end in the winding direction, it is expected that steps will be reduced.

[0015] Hereinafter, an embodiment of the present disclosure (hereinafter may be abbreviated as "the present embodiment") will be described. However, the present embodiment does not limit the technical scope of the present disclosure. The present embodiment is illustrative in all respects. The present embodiment is non-restrictive. The technical scope of the present disclosure encompasses all modifications within the meaning and scope equivalent to the claims. For example, it is also intended from the beginning that any configuration may be extracted from the present embodiment and arbitrarily combined.

[0016] Geometric terms should not be interpreted in a strict sense. Examples of geometric terms include "parallel," "perpendicular," and "orthogonal." For example, "parallel" may deviate slightly from the strict meaning of "parallel." Geometric terms may include, for example, tolerances, errors, etc. in design, work, manufacturing, etc. The dimensional relationships in each figure may not match the actual dimensional relationships. To aid the reader's understanding, the dimensional relationships in each figure may be changed. For example, length, width, thickness, etc. may be changed. Furthermore, some configurations may be omitted. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a storage cell according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing an example of a wound electrode body in the present embodiment. [Figure 3]FIG. 2 is a schematic cross-sectional view showing an example of a fixing member according to the present embodiment. [Figure 4] FIG. 1 is a schematic cross-sectional view showing a first arrangement example. [Figure 5] FIG. 10 is a schematic cross-sectional view showing a second arrangement example. [Figure 6] FIG. 10 is a schematic cross-sectional view showing a third arrangement example. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1. Energy storage cell FIG. 1 is a schematic cross-sectional view showing an example of a storage cell according to this embodiment. The storage cell 1 can be used for any purpose. For example, the storage cell 1 may be used as a power source for a vehicle. The storage cell 1 includes a cell case 200, a wound electrode body 100, and an electrolyte (not shown). The storage cell 1 may further include, for example, an external terminal 300, a positive electrode current collector 410, a negative electrode current collector 420, and an insulating member 500.

[0019] 2. Wound electrode body The wound electrode body 100 is formed by winding an electrode and a separator 130. "Electrode" is a general term for the positive electrode 110 and the negative electrode 120. That is, the wound electrode body 100 includes the positive electrode 110, the negative electrode 120, and the separator 130. The positive electrode 110, the negative electrode 120, and the separator 130 are all strip-shaped. The positive electrode 110, the negative electrode 120, and the separator 130 are all sheet-shaped. For example, the positive electrode 110, the separator 130, and the negative electrode 120 may be stacked in this order to form a laminate. The wound electrode body 100 may be formed by spirally winding the laminate. The wound electrode body 100 may be formed, for example, in a flat shape.

[0020] The positive electrode 110 includes a positive electrode current collector foil 112 and a positive electrode active material layer 114. The positive electrode current collector foil 112 may contain, for example, Al. The positive electrode current collector foil 112 includes a first region 112a and a second region 112b. The positive electrode active material layer 114 is disposed in the first region 112a. The positive electrode active material layer 114 may contain, for example, a lithium-nickel composite oxide. The second region 112b is adjacent to the first region 112a. The second region 112b is disposed at an end in the axial direction. The "axial direction" is the direction A in FIG. 1. The second region 112b has multiple tabs. The multiple tabs are separated in the winding direction of the wound electrode body 100. For example, multiple tabs may be welded to the second region 112b. For example, a portion of the second region 112b may be processed into a tab. Each tab leans inward in the radial direction. The "radial direction" is the R direction in FIG. 1, etc. The outer surface of each tab forms a substantially flat surface. Each tab is connected to a positive current collector plate 410. Each tab may be welded to the positive current collector plate 410.

[0021] The negative electrode 120 includes a negative electrode current collector foil 122 and a negative electrode active material layer 124. The negative electrode current collector foil 122 may contain, for example, Cu, Ni, or the like. The negative electrode current collector foil 122 includes a first region 122a and a second region 122b. The negative electrode active material layer 124 is disposed in the first region 122a. The negative electrode active material layer 124 may contain, for example, graphite, Si, SiO, or the like. The second region 122b is adjacent to the first region 122a. The second region 122b is disposed at an end in the axial direction. The second region 122b has multiple tabs. The multiple tabs are separated in the winding direction of the wound electrode body 100. Each tab leans toward the inside in the radial direction. The outer surface of each tab forms a substantially flat surface. Each tab is connected to a negative electrode current collector plate 420. Each tab may be welded to the negative electrode current collector plate 420.

[0022] The separator 130 is electrically insulating. The separator 130 electrically separates the positive electrode 110 from the negative electrode 120. The separator 130 is disposed between the positive electrode 110 and the negative electrode 120 in the radial direction. The separator 130 is porous. The electrolyte can permeate the separator 130. The separator 130 may include, for example, a porous resin membrane.

[0023] 3. Fixing member FIG. 2 is a schematic diagram showing an example of a wound electrode body in this embodiment. FIG. 2 shows the winding end portion 101 of the wound electrode body 100. The "winding direction" is the W direction in FIG. 2, etc. A fixing member 140 fixes the winding end portion 101. The fixing member 140 may straddle the winding end portion 101. The fixing member 140 may fix a part of the winding end portion 101. The fixing member 140 may fix the entire winding end portion 101. One fixing member 140 may be arranged. Multiple fixing members 140 may be arranged. In the winding direction, the fixing member 140 may have a width of, for example, 1 to 10 mm, or 3 to 7 mm.

[0024] 3-1. Adhesive ingredients The fixing member 140 includes an adhesive component. The adhesive component is soluble in the electrolyte. The adhesive component may include any component as long as it is soluble in the electrolyte. The adhesive component may be, for example, non-self-supporting. A non-self-supporting adhesive component may be supported on a substrate. The adhesive component may be applied to the surface of the substrate. The adhesive component may be impregnated into the substrate. The adhesive component may include, for example, at least one selected from the group consisting of an acrylic adhesive, a silicone adhesive, a urethane adhesive, and a rubber adhesive.

[0025] The adhesive component may be self-supporting. A self-supporting adhesive component can be used without a substrate. The adhesive component may contain at least one adhesive selected from the group consisting of, for example, vinyl acetate resin emulsion adhesives, acrylic resin emulsion adhesives, vinyl acetate resin solvent adhesives, acrylic resin solvent adhesives, vinyl chloride resin solvent adhesives, chloroprene rubber solvent adhesives, chloroprene rubber solvent mastic adhesives, nitrile rubber solvent adhesives, urethane resin adhesives, epoxy resin adhesives, modified silicone resin adhesives, epoxy-modified silicone resin adhesives, starch adhesives, polymer cement mortars, epoxy resin mortars, and silylated urethane resin adhesives.

[0026] The adhesive component may be entirely dissolved. The adhesive component may be partially dissolved. The fixing force may be reduced by dissolving at least a portion of the adhesive component. The fixing of the winding end portion 101 may be completely released by dissolving the adhesive component. The fixing of the winding end portion 101 may be partially released.

[0027] 3-2. Base material FIG. 3 is a schematic cross-sectional view showing an example of a fixing member in this embodiment. Fixing member 140 may include a base material 141. Fixing member 140 may include, for example, base material 141 and an adhesive layer 142. Base material 141 supports adhesive layer 142. When fixing member 140 includes base material 141, improved strength is expected. Base material 141 may be, for example, sheet-shaped. Base material 141 may be, for example, porous. When base material 141 is porous, stress concentration may be alleviated. Base material 141 may include, for example, a sponge, a nonwoven fabric, etc.

[0028] The thickness of the substrate 141 may be, for example, 5 to 50 μm or 10 to 30 μm. The substrate 141 may include, for example, at least one selected from the group consisting of polypropylene (PP), polyimide (PI), polyethylene (PE), polyethylene terephthalate (PET), and polyphenylene sulfide (PPS).

[0029] The adhesive layer 142 may be disposed on only one side of the substrate 141. The adhesive layer 142 may be disposed on both sides of the substrate 141. The adhesive layer 142 may cover the entire substrate 141. The thickness of the adhesive layer 142 may be, for example, 5 to 50 μm or 10 to 30 μm. The adhesive layer 142 contains the adhesive component described above. As long as the adhesive layer 142 contains the adhesive component, it may also contain additional components. The additional components may include, for example, a plasticizer or the like.

[0030] 3-3. Layout example FIG. 4 is a schematic cross-sectional view showing a first arrangement example. FIGS. 4 to 6 show cross sections perpendicular to the axial direction of the wound electrode body 100. The "outermost layer" refers to the component of the positive electrode 110, the negative electrode 120, and the separator 130 that is located radially outermost at the winding end portion 101. The outermost layer may be any of the positive electrode 110, the negative electrode 120, or the separator 130. FIGS. 4 to 6 show, as an example, a configuration in which the separator 130 is the outermost layer. For example, a fixing member 140 may be disposed radially on the outer periphery of the outermost layer. The fixing member 140 may straddle the winding end portion 101.

[0031] 5 is a schematic cross-sectional view showing a second arrangement example. For example, at least a portion of the fixing member 140 may be arranged on the inner periphery side of the outermost layer in the radial direction. In the winding direction, the central portion 140c of the fixing member 140 may be located inside the winding end portion 101. By arranging at least a portion of the fixing member 140 on the inner periphery side of the outermost layer, it is expected that the step caused by the fixing member 140 will be reduced. For example, the protrusion of the fixing member 140 from the winding end portion 101 may be less than half the dimension of the fixing member 140 in the winding direction.

[0032] 6 is a schematic cross-sectional view showing a third arrangement example. In the radial direction, at least a portion of the fixing member 140 may be disposed on the inner circumferential side of the outermost layer. In the winding direction, the base material 141 may be located inside the winding end portion 101. The base material 141 may not be located outside the winding end portion 101. In the third arrangement example, a reduction in steps is also expected. As long as the base material 141 is located inside the winding end portion 101 in the winding direction, the adhesive layer 142 may extend outside the winding end portion 101, for example.

[0033] 4. Electrolyte The electrolyte is a liquid electrolyte. The electrolyte includes a solute and a solvent. The electrolyte may further include an optional additive. The solute includes a supporting electrolyte. The solute may include, for example, at least one selected from the group consisting of LiPF6, LiBF4, LiN(SO2F)2, LiN(SO2CF3)2, LiB(C2O4)2, LiPO2F2, and FSO3Li. The concentration of the solute may be, for example, 0.5 to 2 mol / L.

[0034] The solvent can dissolve the adhesive component. The solvent can contain any component as long as it can dissolve the adhesive component. The solvent may contain, for example, a carbonate-based solvent. The solvent may contain, for example, at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC).

[0035] 5. Cell Case As shown in Figure 1, the cell case 200 houses the wound electrode assembly 100, the fixing member 140, and the electrolyte. The cell case 200 can have any shape. The cell case 200 can be cylindrical, rectangular, or laminated. A laminated cell case 200 is made of a metal foil laminate film.

[0036] The cell case 200 may be made of, for example, metal. The cell case 200 may include, for example, a peripheral wall 210, a top wall 220, and a bottom wall 230. The peripheral wall 210 may have a cylindrical outer shape. The peripheral wall 210 surrounds the outer peripheral surface of the wound electrode body 100. The peripheral wall 210 may be in contact with the outer peripheral surface of the wound electrode body 100.

[0037] The top wall 220 is connected to an end of the peripheral wall 210 in the axial direction. For example, a through-hole for connection to the external terminal 300 may be formed in the center of the top wall 220. The bottom wall 230 faces the top wall 220 in the axial direction. The bottom wall 230 is connected to an end of the peripheral wall 210 in the axial direction. The bottom wall 230 is in contact with the negative electrode current collector plate 420.

[0038] The external terminal 300 is disposed on the outer surface of the top wall 220. In this embodiment, the external terminal 300 has a positive polarity, and the cell casing 200 has a negative polarity.

[0039] The insulating member 500 electrically separates the external terminal 300 from the cell casing 200. The insulating member 500 may include, for example, a first insulating portion 510 and a second insulating portion 520. The first insulating portion 510 is interposed between the external terminal 300 and the top wall 220. Inside the cell casing 200, the second insulating portion 520 is interposed between the positive electrode current collector plate 410 and the cell casing 200. [Explanation of symbols]

[0040] 1 storage cell, 100 wound electrode body, 101 winding end portion, 110 positive electrode, 112 positive electrode current collector foil, 112a, 122a first region, 112b, 122b second region, 114 positive electrode active material layer, 120 negative electrode, 122 negative electrode current collector foil, 124 negative electrode active material layer, 130 separator, 140 fixing member, 140c central portion, 141 substrate, 142 adhesive layer, 200 cell case, 210 peripheral wall, 220 top wall, 230 bottom wall, 300 external terminal, 410 positive electrode current collector plate, 420 negative electrode current collector plate, 500 insulating member, 510 first insulating portion, 520 second insulating portion.

Claims

1. It includes a cell case, a wound electrode body, a fixing member, and an electrolyte, The cell case houses the wound electrode body, the fixing member, and the electrolyte. The cell case includes a peripheral wall, The aforementioned wound electrode body is formed by winding an electrode and a separator, The fixing member fixes the end of the winding in the winding direction of the wound electrode body. The fixing member contains an adhesive component, The adhesive component exhibits solubility in the electrolyte, and The outer circumferential surface of the wound electrode body is in contact with the circumferential wall. Energy storage cell.

2. The fixing member further includes a base material, and The substrate supports the adhesive component. The energy storage cell according to claim 1.

3. In the radial direction of the wound electrode body, at least a portion of the fixing member is arranged on the inner circumference side of the outermost layer of the wound electrode body, and In the winding direction of the wound electrode body, inside the end of the winding of the wound electrode body The central part of the fixing member is located on the side. The energy storage cell according to claim 1.

4. In the radial direction of the wound electrode body, at least a portion of the fixing member is arranged on the inner circumference side of the outermost layer of the wound electrode body. In the winding direction of the wound electrode body, The base material of the fixing member is located inside the end of the winding of the wound electrode body, and The base material of the fixing member is not located outside the end of the winding of the wound electrode body. The energy storage cell according to claim 2.

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