Manufacturing method of power storage cell

Abstract

To reduce the concentration of stress at the end of the winding of a wound electrode body when the wound electrode body expands and contracts.SOLUTION: A manufacturing method of a power storage cell according to the present disclosure includes forming a wound electrode body 100 by winding a positive electrode 110, a negative electrode 120, and a separator 130 (S1), fixing an end portion 101 in the winding direction of the wound electrode body 100 with a fixing member 140 (S2), housing the wound electrode body 100 having the end portion 101 fixed by the fixing member 140 in a cell case 200 (S3), injecting an electrolyte into the cell case 200 (S4), and releasing the fixing of the end portion 101 by the fixing member 140 after the wound electrode body 100 is housed in the cell case 200 and the electrolyte has been injected into the cell case 200 (S5).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing an energy storage cell. [Background technology]

[0002] Patent Document 1 (JP Patent Publication 11-273743 A) discloses a conventional cylindrical nonaqueous electrolyte secondary battery. In the cylindrical nonaqueous electrolyte secondary battery, a spirally wound electrode body is housed in a cylindrical battery can together with a nonaqueous electrolyte. The spirally wound electrode body is formed by winding a strip-shaped negative electrode and a strip-shaped positive electrode with a separator sandwiched therebetween in a spiral shape, and fixing the end of the winding with an adhesive tape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-273743 Summary of the Invention [Problem to be solved by the invention]

[0004] In the secondary battery (storage cell) disclosed in Patent Document 1, the wound electrode body expands and contracts during charging and discharging. During expansion and contraction, the winding end portion fixed with adhesive tape is restricted from displacement relative to the main body of the wound electrode body. As a result, stress is concentrated at the winding end portion of the wound electrode body.

[0005] The object is to provide a method for manufacturing an electricity storage cell, which can manufacture an electricity storage cell in which concentration of stress at the winding end portion of a wound electrode body is alleviated when the wound electrode body expands and contracts. [Means for solving the problem]

[0006] A method for manufacturing a storage cell based on the present disclosure includes forming a wound electrode body by winding a positive electrode, a negative electrode, and a separator, fixing an end portion of the wound electrode body in the winding direction with a fixing member, housing the wound electrode body having the end portion fixed by the fixing member in a cell case, injecting an electrolyte into the cell case, and releasing the fixing of the end portion by the fixing member after the wound electrode body is housed in the cell case and the electrolyte has been injected into the cell case.

[0007] When the electric storage cell is charged and discharged, the wound electrode body expands and contracts. According to the above configuration, since the fixing by the fixing member is released, it is possible to manufacture an electric storage cell in which the concentration of stress on the winding end portion of the wound electrode body when the wound electrode body expands and contracts is alleviated. Effect of the Invention

[0008] According to the present disclosure, it is possible to manufacture an energy storage cell in which concentration of stress at the winding end portion of the wound electrode body is alleviated when the wound electrode body expands and contracts. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a storage cell according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a flow diagram showing a method for manufacturing the energy storage cell according to the present embodiment. [Diagram 3] 1 is a schematic perspective view showing a wound electrode body whose winding end portion is fixed by a fixing member. FIG. [Figure 4] 10 is a schematic cross-sectional view showing a wound electrode body whose winding end portion is fixed by a fixing member. FIG. [Diagram 5] 4 is a schematic cross-sectional view showing the wound electrode body and the cell case immediately after being housed in the cell case. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a method for manufacturing a storage cell according to an embodiment of the present disclosure will be described with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference characters, and description thereof will not be repeated.

[0011] (Energy storage cell) First, a description will be given of a storage cell that can be manufactured by a storage cell manufacturing method according to an embodiment of the present disclosure. Fig. 1 is a schematic cross-sectional view showing an example of a storage cell in this embodiment. The storage cell 1 shown in Fig. 1 can be applied to any purpose. The storage cell 1 may be used, for example, as a power source for a vehicle.

[0012] 1, the energy storage cell 1 includes a cell case 200, a wound electrode body 100, and an electrolyte (not shown). The energy 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.

[0013] The wound electrode body 100 is formed by winding an electrode and a separator 130. The term "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.

[0014] 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 include, for example, Al.

[0015] The positive electrode current collector foil 112 includes a first region 112a and a second region 112b. A positive electrode active material layer 114 is disposed in the first region 112a. The positive electrode active material layer 114 may include, for example, a lithium nickel composite oxide.

[0016] The second region 112b is adjacent to the first region 112a. The second region 112b is disposed at the end in the axial direction. The "axial direction" is the A direction in FIG. 1. The second region 112b has a plurality of tabs. The plurality of tabs are separated in the winding direction of the wound electrode body 100. For example, a plurality of tabs may be welded to the second region 112b. For example, a part of the second region 112b may be processed into a tab. Each tab is inclined toward the inside 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 the positive electrode current collector 410. Each tab may be welded to the positive electrode current collector 410.

[0017] 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 include, for example, Cu, Ni, or the like.

[0018] The negative electrode current collector foil 122 includes a first region 122a and a second region 122b. A negative electrode active material layer 124 is disposed in the first region 122a. The negative electrode active material layer 124 may include, for example, graphite, Si, SiO, or the like.

[0019] 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 a plurality of tabs. The plurality of tabs are separated in the winding direction of the wound electrode body 100. Each tab is inclined toward the inside in the radial direction. The outer surface of each tab forms a substantially flat surface. Each tab is connected to the negative electrode current collector 420. Each tab may be welded to the negative electrode current collector 420. Each tab may be welded to the bottom wall 230 of the cell case 200 described later.

[0020] The separator 130 has electrical insulation properties. The separator 130 electrically separates the positive electrode 110 from the negative electrode 120. In the radial direction, the separator 130 is disposed between the positive electrode 110 and the negative electrode 120. The separator 130 is porous. The electrolyte can permeate the separator 130. The separator 130 may include, for example, a porous membrane made of resin.

[0021] The outermost layer of the wound electrode body 100 may be an electrode or a separator 130. The "outermost layer" refers to the member located radially outward at the end of the winding of the wound electrode body 100, which will be described later, among the positive electrode 110, the negative electrode 120, and the separator 130. In this embodiment, the outermost layer of the wound electrode body 100 is an electrode. That is, the outermost layer of the wound electrode body 100 is the positive electrode 110 or the negative electrode 120. Specifically, the outermost layer of the wound electrode body 100 is the negative electrode 120. More specifically, the outermost layer is the negative electrode active material layer 124, but may also be the negative electrode current collector foil 122.

[0022] The outermost layer is in contact with cell casing 200. Specifically, the outermost layer is in close contact with peripheral wall 210, which will be described later. The portion of cell casing 200 that is in contact with the outermost layer (i.e., peripheral wall 210) is made of a conductive material.

[0023] The electrolyte is a liquid electrolyte. The electrolyte includes a solute and a solvent. The electrolyte may further include any additive. The solute includes a supporting electrolyte. The solute may include 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.

[0024] In this embodiment, the solvent can dissolve the adhesive component of the fixing member described below. 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).

[0025] As shown in Fig. 1, the cell case 200 contains the wound electrode body 100, the fixing member 140, and the electrolyte. The cell case 200 may have any shape. The cell case 200 may be cylindrical, rectangular, or laminated. The laminated cell case 200 is made of a metal foil laminate film.

[0026] 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 circumferential surface of the wound electrode body 100. In this embodiment, the peripheral wall 210 is in close contact with the outermost layer of the wound electrode body 100. The peripheral wall 210 is formed of a metal such as aluminum or an aluminum alloy, copper, or stainless steel.

[0027] 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 peripheral wall 210 and the bottom wall 230 are in contact with the negative electrode current collector plate 420. Either the peripheral wall 210 or the bottom wall 230 may be in contact with the negative electrode current collector plate 420. The peripheral wall 210 and the bottom wall 230 may be insulated from each other via an insulating member.

[0028] At least one of the top wall 220 and the bottom wall 230 may be provided with a liquid injection port (not shown) for injecting an electrolyte into the cell casing 200.

[0029] 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. The cell casing 200 has a negative polarity. When the peripheral wall 210 and the bottom wall 230 are insulated from each other, only the bottom wall 230 may have a negative polarity, or only the peripheral wall 210 and the top wall 220 of the cell casing 200 may have a negative polarity.

[0030] 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.

[0031] (Method of manufacturing energy storage cells) Next, a method for producing a storage cell according to an embodiment of the present disclosure will be described below. Fig. 2 is a flow diagram showing the method for producing a storage cell according to the present embodiment.

[0032] As shown in FIG. 2, the method for manufacturing a storage cell according to this embodiment includes a step S1 of forming a wound electrode body, a step S2 of fixing the end of the winding, a step S3 of housing the wound electrode body in a cell case, a step S4 of injecting an electrolyte, and a step S5 of releasing the fixation of the end of the winding.

[0033] In step S1, the positive electrode 110, the negative electrode 120, and the separator 130 are wound to form the wound electrode body 100 (see FIG. 1). Note that the radial dimension of the wound electrode body 100 formed at the time of step S1 is formed to be smaller than the radial dimension of the wound electrode body 100 shown in FIG.

[0034] Fig. 3 is a schematic perspective view showing a wound electrode body whose winding end portion is fixed by a fixing member. Fig. 4 is a schematic cross-sectional view showing a wound electrode body whose winding end portion is fixed by a fixing member. As shown in Figs. 3 and 4, in step S2, winding end portion 101 in the winding direction of wound electrode body 100 is fixed by fixing member 140. Figs. 3 and 4 show winding end portion 101 of wound electrode body 100.

[0035] The "winding direction" is the W direction shown in Figures 3 and 4. The fixing member 140 fixes the winding end portion 101. The fixing member 140 is provided on the inner periphery side of the winding end portion 101 in the radial direction. The fixing member 140 may be provided, in part or in whole, on the inner periphery side of the winding end portion 101 in the radial direction. The fixing member 140 may be provided on the outer periphery side of the winding end portion 101 in the radial direction. The fixing member 140 may be provided so as to straddle the edge of the winding end portion 101 in the winding direction.

[0036] The fixing member 140 is provided on the inner periphery side of the outermost layer (specifically, the negative electrode 120) of the wound electrode body 100 in the radial direction. A part or the whole of the fixing member 140 may be provided on the inner periphery side of the outermost layer in the radial direction. The fixing member 140 may be provided on the outer periphery side of the outermost layer in the radial direction. The fixing member 140 may be provided so as to straddle the edge of the outermost layer in the winding direction. The fixing member 140 may be provided in one region of the winding end portion 101, or multiple fixing members 140 may be provided in multiple regions of the winding end portion 101. In the winding direction, the fixing member 140 may have a width of, for example, 1 to 10 mm, or 3 to 7 mm.

[0037] Fixing member 140 may be a hot melt adhesive. In step S2, the hot melt adhesive is melted or softened by heating, and heat-sealed to both the outermost layer of winding end portion 101 and the layer that constitutes its inner periphery. Then, the adhesive is cooled and solidified, thereby fixing winding end portion 101.

[0038] Examples of hot melt adhesives include rubber-based hot melt adhesives, polyester-based hot melt adhesives, polyolefin-based hot melt adhesives, ethylene-vinyl acetate resin-based hot melt adhesives, polyamide resin hot melt adhesives, and polyurethane resin hot melt adhesives. The softening temperature (ring and ball method) of the hot melt adhesive is, for example, 50°C or higher and 200°C. The softening temperature of the hot melt adhesive is preferably as low as possible, for example, preferably lower than 100°C, and more preferably 80°C or lower. The softening temperature of the hot melt adhesive is most preferably about 60°C.

[0039] The fixing member 140 may be formed from a material that is soluble in the electrolyte. More specifically, the outer surface of the fixing member 140 may be formed from a material that is soluble in the electrolyte.

[0040] When the fixing member 140 is formed of a material that is soluble in the electrolyte, the fixing member 140 or its outer surface contains an adhesive component. This adhesive component is soluble in the electrolyte. The adhesive component may contain any component as long as it can be dissolved in the electrolyte. The adhesive component may be, for example, a non-self-supporting type. When the fixing member 140 further includes a substrate, the non-self-supporting adhesive component may be supported by the 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.

[0041] The adhesive component may be a self-supporting type. A self-supporting adhesive component may be used without a substrate. The adhesive component may include at least one selected from the group consisting of, for example, vinyl acetate resin-based emulsion adhesive, acrylic resin-based emulsion adhesive, vinyl acetate resin-based solvent-based adhesive, acrylic resin-based solvent-based adhesive, vinyl chloride resin-based solvent-based adhesive, chloroprene rubber-based solvent-based adhesive, chloroprene rubber-based solvent-based mastic-type adhesive, nitrile rubber-based solvent-based adhesive, urethane resin-based adhesive, epoxy resin-based adhesive, modified silicone resin-based adhesive, epoxy modified silicone resin-based adhesive, starch-based adhesive, polymer cement mortar, epoxy resin mortar, and silylated urethane resin-based adhesive.

[0042] 5 is a schematic cross-sectional view showing the wound electrode body and the cell case immediately after being housed in the cell case. As shown in FIG. 5, in step S3, the wound electrode body 100 having the winding end portion 101 fixed by the fixing member 140 is housed in the cell case 200. Also, immediately after step S3, the wound electrode body 100 does not have to be in contact with the peripheral wall 210 of the cell case 200.

[0043] In step S4, an electrolyte is injected into cell casing 200. Specifically, the electrolyte can be injected through an injection port formed in top wall 220 or bottom wall 230.

[0044] In step S5, after step S3 in which the wound electrode body 100 is housed in the cell case 200 and step S4 in which an electrolyte is injected into the cell case 200, the fixing of the winding end portion 101 by the fixing member 140 is released.

[0045] When the fixing member 140 is a hot melt adhesive, the fixing of the winding end portion 101 by the fixing member 140 may be released by heating the electrolyte injected into the cell case 200 in step S5. The heating method may be a method of heating the energy storage cell 1 from the outside, or a method of causing the wound electrode body 100 to generate heat by charging and discharging the energy storage cell 1. The hot melt adhesive is melted and softened again by the heating. As a result, the winding end portion 101 is again separated from the part on the inner periphery side of the wound electrode body 100. The fixation of the winding end portion 101 is released.

[0046] If the fixing member 140 is formed from a material that is soluble in the electrolyte, the fixing of the end portion 101 by the fixing member 140 may be released by treating the fixing member 140 so that it dissolves in the electrolyte injected into the cell case 200.

[0047] When the fixing member 140 or a part thereof is formed from a material exhibiting solubility, the specific method of the above treatment can be appropriately selected according to the solubility of the fixing member 140 or the adhesive material constituting a part thereof in the solvent of the electrolyte. For example, the above treatment may be a method of leaving the fixing member 140 at room temperature for a predetermined time, a method of heating the energy storage cell 1 from the outside, or a method of causing the wound electrode body 100 to generate heat by charging and discharging the energy storage cell 1.

[0048] 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.

[0049] In step S5, the fixing of the winding end portion 101 by the fixing member 140 is released, thereby bringing the outermost layer of the wound electrode body into contact with the cell case 200 (see FIGS. 1 and 5). By releasing the above-mentioned fixing, the winding of the wound electrode body 100 loosens. As a result, the portion of the wound electrode body 100 including the winding end portion 101 that faces the peripheral wall 210 is displaced radially outward. Then, the outermost layer of the wound electrode body 100 comes into close contact with the peripheral wall 210 of the cell case 200.

[0050] As described above, the manufacturing method of a storage cell according to one embodiment of the present disclosure includes forming a wound electrode body 100 by winding a positive electrode 110, a negative electrode 120, and a separator 130 (S1), fixing an end portion 101 in the winding direction of the wound electrode body 100 with a fixing member 140 (S2), housing the wound electrode body 100 having the end portion 101 fixed by the fixing member 140 in a cell case 200 (S3), injecting an electrolyte into the cell case 200 (S4), and releasing the fixing of the end portion 101 by the fixing member 140 after the wound electrode body 100 is housed in the cell case 200 and the electrolyte has been injected into the cell case 200 (S5).

[0051] When the energy storage cell 1 is charged and discharged, the wound electrode body 100 expands and contracts. According to the above configuration, since the fixing by the fixing member 140 is released during manufacturing, it is possible to manufacture an energy storage cell 1 in which the concentration of stress on the winding end portion of the wound electrode body 100 is alleviated when the wound electrode body 100 expands and contracts.

[0052] Furthermore, in this embodiment, the fixing member 140 may be a hot melt adhesive. Then, the fixing of the winding end portion 101 by the fixing member 140 may be released by heating the electrolyte injected into the cell case 200 (S5).

[0053] According to the above configuration, it is possible to suppress a change in the properties of the electrolyte solution caused by the fixing member 140 being dissolved in the electrolyte solution.

[0054] Furthermore, in this embodiment, the fixing member 140 may be made of a material that is soluble in the electrolyte. Then, the fixing of the winding end portion 101 by the fixing member 140 may be released by treating the fixing member 140 so that it dissolves in the electrolyte injected into the cell case 200 (S5).

[0055] According to the above configuration, the fixing member 140 dissolves in the electrolyte, and the total volume of the members housed in the cell case 200 is reduced by the volume of the fixing member 140 before dissolution. This can further reduce the concentration of stress on parts of the wound electrode body 100 and the cell case 200 when the wound electrode body 100 expands.

[0056] Furthermore, in this embodiment, the outermost layer of the wound electrode body 100 is the positive electrode 110 or the negative electrode 120. Then, the fixing of the winding end portion 101 by the fixing member 140 is released (S5), thereby bringing the outermost layer into contact with the cell case 200.

[0057] According to the above configuration, heat generated from the wound electrode body 100 is easily transferred to the cell case 200 via the outermost layer. This allows the heat to be effectively released to the outside of the energy storage cell 1.

[0058] Furthermore, in this embodiment, the portion of cell casing 200 that contacts the outermost layer is made of a conductive material.

[0059] The conductive material has a relatively high thermal conductivity. Therefore, according to the above configuration, the heat generated from the wound electrode body 100 is more easily transferred to the cell case 200 via the outermost layer. This allows the heat to be more effectively dissipated to the outside of the energy storage cell 1.

[0060] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not by the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0061] 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, 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. forming a wound electrode body by winding the positive electrode, the negative electrode, and the separator; Fixing a winding end portion of the wound electrode body in a winding direction with a fixing member; housing the wound electrode body having the winding end portion fixed by the fixing member in a cell case; injecting an electrolyte into the cell casing; and releasing the fixation of the winding end portion by the fixing member after the wound electrode body is contained in the cell case and the electrolyte is injected into the cell case.

2. The fixing member is a hot melt adhesive, The method for producing a storage cell according to claim 1 , wherein the fixing of the winding end portion by the fixing member is released by heating the electrolyte injected into the cell case.

3. the fixing member is made of a material that is soluble in the electrolyte, The method for producing a storage cell according to claim 1 , further comprising the steps of: releasing the fixing of the winding end portion by the fixing member by treating the fixing member so that the fixing member is dissolved in the electrolyte injected into the cell case.

4. the outermost layer of the wound electrode body is the positive electrode or the negative electrode, The method for producing a storage cell according to claim 1 , wherein the outermost layer is brought into contact with the cell case by releasing the fixing of the winding end portion by the fixing member.

5. The method for producing a storage cell according to claim 4 , wherein a portion of the cell casing that contacts the outermost layer is made of a conductive material.

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