Manufacturing method of energy storage cells

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 a storage cell.

Background Art

[0002] Patent Document 1 (Japanese Patent Application Laid-Open No. 11-273743) discloses a conventional cylindrical non-aqueous electrolyte secondary battery. In the cylindrical non-aqueous electrolyte secondary battery, a spiral electrode body is housed in a cylindrical battery can together with a non-aqueous electrolyte. The spiral electrode body is formed by winding a strip-shaped negative electrode and a strip-shaped positive electrode in a spiral shape with a separator interposed therebetween, and fixing the winding end portion thereof using an adhesive tape.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the secondary battery (storage cell) disclosed in Patent Document 1, during charging and discharging, the wound electrode body expands and contracts. When expanding and contracting, the displacement of the winding end portion fixed with the adhesive tape with respect to the main body of the wound electrode body is suppressed. As a result, stress concentrates on the winding end portion of the wound electrode body.

[0005] An object of the present invention is to provide a method for manufacturing a storage cell capable of manufacturing a storage cell in which stress concentration on the winding end portion of the wound electrode body is alleviated when the wound electrode body expands and contracts.

Means for Solving the Problems

[0006] A method for manufacturing an energy storage cell according to this disclosure comprises forming a wound electrode body by winding a positive electrode, a negative electrode, and a separator; fixing the end of the winding in the winding direction of the wound electrode body with a fixing member; housing the wound electrode body having the end of the winding fixed by the fixing member in a cell case; injecting an electrolyte into the cell case; and releasing the fixing of the end of the winding by the fixing member after the wound electrode body has been housed in the cell case and the electrolyte has been injected into the cell case.

[0007] When a storage cell is charged and discharged, the wound electrode expands and contracts. With the above configuration, since the fixing by the fixing member is released, it is possible to manufacture a storage cell in which stress concentration at the end of the winding of the wound electrode is mitigated when the wound electrode expands and contracts. [Effects of the Invention]

[0008] According to this disclosure, it is possible to manufacture an energy storage cell in which stress concentration at the end of the winding of the winding electrode body is mitigated when the winding electrode body expands and contracts. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing an example of a storage cell in this embodiment. [Figure 2] This is a flowchart illustrating the manufacturing method of the energy storage cell according to this embodiment. [Figure 3] This is a schematic perspective view showing a wound electrode body with the end of the winding fixed by a fixing member. [Figure 4] This is a schematic cross-sectional view showing a wound electrode body with the end of the winding fixed by a fixing member. [Figure 5] This is a schematic cross-sectional view showing the wound electrode body and the cell case immediately after being housed in the cell case. [Modes for carrying out the invention]

[0010] Hereinafter, a method for manufacturing an energy storage cell according to one embodiment of this disclosure will be described with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated.

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

[0012] As shown in Figure 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 plate 410, a negative electrode current collector plate 420, and an insulating member 500.

[0013] The wound electrode body 100 is formed by winding electrodes and a separator 130. "Electrode" is a collective 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 in the shape of strips. The positive electrode 110, the negative electrode 120, and the separator 130 are all in the shape of sheets. For example, a laminate may be formed by stacking the positive electrode 110, the separator 130, and the negative electrode 120 in this order. The wound electrode body 100 may be formed by winding the laminate in a spiral shape. The wound electrode body 100 may be formed in a flat shape, for example.

[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 contain, 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 contain, 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 an axial end. 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 tilted inward in the radial direction. The "radial direction" is the R direction in FIG. 1 and the like. The outer surface of each tab forms a substantially flat surface. Each tab is connected to the positive current collector plate 410. Each tab may be welded to the positive current collector plate 410.

[0017] The negative electrode 120 includes a negative current collector foil 122 and a negative electrode active material layer 124. The negative current collector foil 122 may contain, for example, Cu, Ni, or the like.

[0018] The negative 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.

[0019] The second region 122b is adjacent to the first region 122a. The second region 122b is disposed at an axial end. 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 tilted inward in the radial direction. The outer surface of each tab forms a substantially flat surface. Each tab is connected to the negative current collector plate 420. Each tab may be welded to the negative current collector plate 420. Each tab may be welded to the bottom wall 230 of the cell case 200 described later.

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

[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 outermost in the radial direction at the end of winding of the wound electrode body 100 to be described later among the positive electrode 110, the negative electrode 120, and the separator 130. In the present 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 it may be the negative electrode current collector foil 122.

[0022] The outermost layer is in contact with the cell case 200. Specifically, the outermost layer is in close contact with a peripheral wall 210 to be described later. The portion of the cell case 200 that contacts the outermost layer (that is, the 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, 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, from 0.5 to 2 mol / L.

[0024] In this embodiment, the solvent can dissolve the adhesive component of the fixing member described later. The solvent may contain any component as long as it can dissolve the adhesive component. The solvent may, for example, include 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 Figure 1, the cell case 200 houses the wound electrode body 100, the fixing member 140, and the electrolyte. The cell case 200 can 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 made of a metal such as aluminum or an aluminum alloy, copper, or stainless steel.

[0027] The top wall 220 is connected to the axial end of the peripheral wall 210. For example, a through hole may be formed in the center of the top wall 220 for connection to an external terminal 300. In the axial direction, the bottom wall 230 is opposite to the top wall 220. The bottom wall 230 is connected to the axial end of the peripheral wall 210. 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] The top wall 220 and the bottom wall 230 may each have an injection port (not shown) for injecting electrolyte into the cell case 200.

[0029] The external terminal 300 is located on the outer surface of the top wall 220. In this embodiment, the external terminal 300 has positive polarity. The cell case 200 has negative polarity. If the peripheral wall 210 and the bottom wall 230 are insulated from each other, only the bottom wall 230 may have negative polarity, or only the peripheral wall 210 and the top wall 220 of the cell case 200 may have negative polarity.

[0030] The insulating member 500 electrically isolates the external terminal 300 from the cell case 200. The insulating member 500 may include, for example, a first insulating section 510 and a second insulating section 520. The first insulating section 510 is interposed between the external terminal 300 and the top wall 220. Inside the cell case 200, the second insulating section 520 is interposed between the positive electrode current collector plate 410 and the cell case 200.

[0031] (Manufacturing method for energy storage cells) Next, a method for manufacturing an energy storage cell according to one embodiment of this disclosure will be described. Figure 2 is a flowchart showing the method for manufacturing an energy storage cell according to this embodiment.

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

[0033] In step S1, the wound electrode body 100 is formed by winding the positive electrode 110, the negative electrode 120, and the separator 130 (see Figure 1). The radial dimensions of the wound electrode body 100 formed in step S1 are formed to be smaller than the radial dimensions of the wound electrode body 100 shown in Figure 1.

[0034] Figure 3 is a schematic perspective view showing a wound electrode body with the end of the winding fixed by a fixing member. Figure 4 is a schematic cross-sectional view showing a wound electrode body with the end of the winding fixed by a fixing member. As shown in Figures 3 and 4, in step S2, the end of the winding 101 in the winding direction of the wound electrode body 100 is fixed by a fixing member 140. Figures 3 and 4 show the end of the winding 101 of the 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 circumference side of the winding end portion 101 in the radial direction. Part of the fixing member 140, or all of it, may be provided on the inner circumference side of the winding end portion 101 in the radial direction. The fixing member 140 may be provided on the outer circumference 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 circumference side of the outermost layer (specifically the negative electrode 120) of the wound electrode body 100 in the radial direction. Part or all of the fixing member 140 may be provided on the inner circumference side of the outermost layer in the radial direction. The fixing member 140 may be provided on the outer circumference 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 each of 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] The fixing member 140 may be a hot melt adhesive. In step S2, the hot melt adhesive is melted or softened by heating and heat-fused to both the outermost layer and the inner circumference layer of the winding end portion 101. Then, the winding end portion 101 is fixed by solidification through subsequent cooling.

[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-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 less than 100°C, and more preferably 80°C or lower. The softening temperature of the hot-melt adhesive is most preferably around 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] If the fixing member 140 is formed from 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 is soluble in the electrolyte. The adhesive component may be, for example, non-self-supporting. If 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 coated on the surface of the substrate. The adhesive component may be impregnated into the substrate. The adhesive component may contain, for example, at least one selected from the group consisting of acrylic adhesives, silicone adhesives, urethane adhesives, and rubber adhesives.

[0041] The adhesive component may be self-supporting. Self-supporting adhesive components can be used without a substrate. The adhesive component may include, for example, at least one selected from the group consisting of 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-type 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.

[0042] Figure 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 Figure 5, in step S3, the wound electrode body 100, which has a winding end portion 101 fixed by the fixing member 140, is housed in the cell case 200. Immediately after step S3, the wound electrode body 100 does not need to be in contact with the peripheral wall 210 of the cell case 200.

[0043] In step S4, electrolyte is injected into the cell case 200. Specifically, the electrolyte can be injected through an injection port formed in the top wall 220 or the 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 electrolyte is injected into the cell case 200, the fixing member 140 releases the fixing of the end portion 101 of the winding.

[0045] If the fixing member 140 is a hot melt adhesive, in step S5, 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. The heating method may be a method of heating the energy storage cell 1 from the outside, or a method of generating heat in the winding electrode body 100 by charging and discharging the energy storage cell 1. Due to the above heating, the hot melt adhesive melts and softens again. As a result, the winding end portion 101 separates again from the inner circumference portion of the winding electrode body 100. The fixing of the winding end portion 101 is released.

[0046] If the fixing member 140 is made of a material that is soluble in the electrolyte, the fixing member 140 may be used to release the fixing of the winding end portion 101 by dissolving the fixing member 140 in the electrolyte injected into the cell case 200.

[0047] If the fixing member 140 or a part thereof is made of a soluble material, the specific method of the above treatment can be appropriately selected depending on the solubility of the adhesive member constituting the fixing member 140 or a part thereof in the solvent of the electrolyte. For example, the above treatment may be a method of leaving it standing at room temperature for a predetermined time, a method of heating the energy storage cell 1 from the outside, or a method of generating heat in the wound electrode body 100 by charging and discharging the energy storage cell 1.

[0048] Furthermore, the entire adhesive component may dissolve. A portion of the adhesive component may dissolve. Dissolving at least a portion of the adhesive component may reduce the fixing force. Dissolving the adhesive component may completely release the fixing of the end portion 101. The fixing of the end portion 101 may be partially released.

[0049] In step S5, the fixing member 140 releases the fixing of the winding end portion 101, bringing the outermost layer of the wound electrode body into contact with the cell case 200 (see Figures 1 and 5). As the fixing is released, 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. The outermost layer of the wound electrode body 100 then comes into close contact with the peripheral wall 210 of the cell case 200.

[0050] As described above, a method for manufacturing an energy storage cell according to one embodiment of the present disclosure comprises: forming a wound electrode body 100 by winding a positive electrode 110, a negative electrode 120, and a separator 130 (S1); fixing the end portion 101 of 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 has been 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. With 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 stress concentration at the end of the winding of the wound electrode body 100 is mitigated when the wound electrode body 100 expands and contracts.

[0052] Furthermore, in this embodiment, the fixing member 140 may be 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 (S5).

[0053] According to the above configuration, it is possible to suppress changes in the properties of the electrolyte due to the dissolution of the fixing member 140 in the electrolyte.

[0054] Furthermore, in this embodiment, the fixing member 140 may be made of a material that is soluble in the electrolyte. The fixing member 140 may then be used to dissolve the fixing member 140 in the electrolyte injected into the cell case 200, thereby releasing the fixing of the winding end portion 101 by the fixing member 140 (S5).

[0055] According to the above configuration, when the fixing member 140 dissolves in the electrolyte, the total volume of the components housed in the cell case 200 is reduced by the volume of the fixing member 140 before dissolution. This further reduces the concentration of stress on a portion 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 either a positive electrode 110 or a negative electrode 120. Then, by releasing the fixing of the end portion 101 of the winding by the fixing member 140 (S5), the outermost layer is brought into contact with the cell case 200.

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

[0058] Furthermore, in this embodiment, the portion of the cell case 200 that comes into contact with the outermost layer is made of a conductive material.

[0059] Conductive materials have relatively high thermal conductivity. Therefore, with the above configuration, the heat generated from the wound electrode body 100 is more easily transferred to the cell case 200 through the outermost layer. As a result, the heat can be more effectively released to the outside of the energy storage cell 1.

[0060] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0061] 1 Energy storage cell, 100 Winding electrode body, 101 End of winding, 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 part, 520 Second insulating part.

Claims

1. The winding electrode body is formed by winding a positive electrode, a negative electrode, and a separator. The end of the winding in the winding direction of the winding electrode body is fixed with a hot melt adhesive, The wound electrode body having the winding end portion fixed by the hot melt adhesive is housed in the cell case, The electrolyte is injected into the aforementioned cell case, A method for manufacturing an energy storage cell, comprising: housing the wound electrode body in the cell case; and after the electrolyte is injected into the cell case, heating the electrolyte injected into the cell case to melt and soften the hot melt adhesive, thereby releasing the fixing of the end of the winding by the hot melt adhesive.

2. The outermost layer of the wound electrode body is the positive electrode or the negative electrode. A method for manufacturing an energy storage cell according to claim 1, wherein the fixing of the end of the winding by the hot melt adhesive is released, thereby bringing the outermost layer into contact with the cell case.

3. The method for manufacturing an energy storage cell according to claim 2, wherein the portion of the cell case that contacts the outermost layer is made of a conductive material.

4. A method for manufacturing an energy storage cell according to any one of claims 1 to 3, wherein the method for heating the electrolyte injected into the cell case to melt and soften the hot melt adhesive includes heating the energy storage cell from the outside.

5. A method for manufacturing an energy storage cell according to any one of claims 1 to 3, wherein the method for heating the electrolyte injected into the cell case to melt and soften the hot melt adhesive includes generating heat in the wound electrode body by charging and discharging the energy storage cell.

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