Energy storage cell

Abstract

To provide a storage cell capable of suppressing uneven distribution of stress occurring in an electrode body when the electrode body expands. [Solution] The energy storage cell includes an electrode assembly configured as a wound body in which a positive electrode sheet 110 and a negative electrode sheet 120 are wound with a separator 130 interposed therebetween. The separator 130 has a separator layer 132 and an adhesive layer 134 provided on at least one of the inner and outer surfaces of the separator layer in the radial direction of the electrode assembly. The terminal end of the electrode assembly is adhered by the adhesive layer 134 to a portion of the electrode assembly located toward the terminal end in the radial direction.

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open No. 2010-212086 discloses a nonaqueous electrolyte secondary battery including a wound electrode assembly in which a positive electrode plate and a negative electrode plate are wound together with a separator sandwiched therebetween and insulated from each other, and a battery outer can that houses the wound electrode assembly. The wound electrode assembly has a separator disposed on the outermost periphery and fixed to the outermost periphery of the wound electrode assembly with a winding tape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-212086 Summary of the Invention [Problem to be solved by the invention]

[0004] In a storage cell equipped with a wound electrode body such as that described in JP 2010-212086 A, the diameter of the portion of the electrode body where the stop tape is attached is larger than the diameter of the other portions, and therefore, when the electrode body expands, a relatively large stress is generated in the portion where the stop tape is attached.

[0005] An object of the present disclosure is to provide an energy storage cell and a method for manufacturing the energy storage cell that can prevent the stress distribution generated in the electrode body from becoming uneven when the electrode body expands. [Means for solving the problem]

[0006] An energy storage cell according to one aspect of the present disclosure includes an electrode body having a positive electrode sheet, a negative electrode sheet, and a separator, and configured as a wound body in which the positive electrode sheet and the negative electrode sheet are wound with the separator interposed therebetween, the separator having a separator layer and an adhesive layer provided on at least one of an inner surface and an outer surface of the separator layer in a radial direction of the electrode body, and an end portion of the electrode body is adhered by the adhesive layer to a portion of the electrode body that is located inside the end portion in the radial direction.

[0007] A method for manufacturing a storage cell according to one aspect of the present disclosure includes a winding step of forming an electrode body composed of a wound body by winding a positive electrode sheet and a negative electrode sheet with a separator interposed therebetween, and an end portion fixing step of fixing an end portion of the electrode body, wherein the separator used in the winding step has a separator layer and an adhesive layer provided on at least one of the inner surface and the outer surface of the separator layer in the radial direction of the electrode body, and in the end portion fixing step, the end portion is adhered to a portion of the electrode body located inside the end portion by the adhesive layer. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an energy storage cell and a method for manufacturing an energy storage cell that can prevent uneven distribution of stress occurring in an electrode body when the electrode body expands. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view schematically illustrating a storage cell according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a front view schematically showing an electrode body. [Figure 3] FIG. 4 is a cross-sectional view schematically showing the vicinity of an extension portion of a separator. [Figure 4] FIG. 10 is a cross-sectional view schematically showing a modified example of the electrode body. [Figure 5] FIG. 10 is a cross-sectional view schematically showing a modified example of the electrode body. [Figure 6]FIG. 10 is a cross-sectional view schematically showing a modified example of the electrode body. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present disclosure will be described with reference to the accompanying drawings, in which the same or corresponding elements are designated by the same reference numerals.

[0011] 1 is a partial cross-sectional view schematically illustrating an energy storage cell according to an embodiment of the present disclosure. The energy storage cell 1 is preferably mounted on a vehicle.

[0012] As shown in FIG. 1, the energy storage cell 1 includes an electrode assembly 100, a cell case 200, an external terminal 300, a positive electrode current collector plate 410, a negative electrode current collector plate 420, an insulating member 500, and an electrolyte (not shown).

[0013] The electrode body 100 has a positive electrode sheet 110, a negative electrode sheet 120, and a separator 130. The electrode body 100 is configured as a wound body in which the positive electrode sheet 110 and the negative electrode sheet 120 are wound around a winding core A with the separator 130 interposed therebetween.

[0014] As shown in FIG. 1, the positive electrode sheet 110 includes a positive electrode current collector foil 112 and a positive electrode active material layer 114.

[0015] The positive electrode current collector foil 112 is made of a metal such as aluminum, and has a main region 112a and an end region 112b.

[0016] The main region 112a is a region of the positive electrode current collector foil 112 where the positive electrode active material layer 114 is provided. As shown in Fig. 1, the main regions 112a are arranged so as to overlap each other in the radial direction of the electrode body 100 (the left-right direction in Fig. 1).

[0017] The end region 112b is a region of the positive electrode current collector foil 112 where the positive electrode active material layer 114 is not provided. As shown in Fig. 1, the end region 112b is formed outside (on the upper side in Fig. 1) the main region 112a in the axial direction of the electrode body 100 (the vertical direction in Fig. 1).

[0018] The end region 112b has a plurality of tabs that are separated from one another in the circumferential direction of the electrode body 100. Each tab leans inward in the radial direction. The upper surface of each tab forms a substantially flat surface. A positive electrode current collector plate 410 is connected to each tab by welding or the like.

[0019] The negative electrode sheet 120 has a negative electrode current collector foil 122 made of a metal such as copper, and a negative electrode active material layer 124 provided on the surface of the negative electrode current collector foil 122 .

[0020] The structure of the negative electrode current collector foil 122 is substantially the same as that of the positive electrode current collector foil 112. Therefore, the description of the negative electrode current collector foil 122 will be simplified. That is, the negative electrode current collector foil 122 has a main region 122a in which a negative electrode active material layer 124 is provided, and an end region 122b formed outside the main region 122a in the axial direction (the lower side in FIG. 1). The end region 122b has multiple tabs separated from each other in the circumferential direction, and each tab leans inward in the radial direction. A negative electrode current collector plate 420 is connected to each tab by welding or the like.

[0021] The separator 130 is disposed between the positive electrode sheet 110 and the negative electrode sheet 120. More specifically, the separator 130 is disposed only between the main region 112a of the positive electrode sheet 110 and the main region 122a of the negative electrode sheet 120, which are adjacent to each other in the radial direction. The separator 130 is made of an insulating material and allows ions to pass through.

[0022] As shown in FIG. 3, the separator 130 includes a separator layer 132 and an adhesive layer 134 .

[0023] The adhesive layer 134 is provided on at least one of the inner and outer radial surfaces of the separator layer 132. In the example shown in Fig. 3, the adhesive layer 134 is provided only on the inner radial surface of the separator layer 132. However, the adhesive layer 134 may be provided only on the outer radial surface of the separator layer 132. The adhesive layer 134 improves the adhesion of the electrode sheets 110, 120 to the separator layer 132.

[0024] As shown in FIGS. 2 and 3, the separator 130 has an extension 135. In FIG. 2, the extension 135 is indicated by a dotted pattern. The extension 135 extends in the circumferential direction longer than the end 119 of the positive electrode sheet 110 and the end 129 of the negative electrode sheet 120. The extension 135 is adhered to a portion of the separator 130 located radially inside the extension 135 by an adhesive layer 134. As shown in FIG. 3, the extension 135 is adhered (welded) by heating using jigs 4 and 5. After the extension 135 is adhered, the jig 4 is pulled out of the electrode assembly 100 in the axial direction.

[0025] The cell case 200 houses the electrode assembly 100. An electrolyte (not shown) is housed inside the cell case 200. The cell case 200 is sealed. The cell case 200 is made of a metal such as aluminum. The cell case 200 has a cylindrical portion 210, a top wall 220, and a bottom wall 230.

[0026] The cylindrical portion 210 surrounds the outer circumferential surface of the electrode body 100 . The top wall 220 is connected to the upper end of the cylindrical portion 210. A through hole for inserting the external terminal 300 is formed in the center of the top wall 220.

[0027] The bottom wall 230 is connected to the lower end of the cylindrical portion 210 by welding or the like. The bottom wall 230 is in contact with the negative electrode current collector plate 420.

[0028] The external terminal 300 is formed above the top wall 220. In this embodiment, the external terminal 300 constitutes a positive electrode external terminal, and the cell case 200 constitutes a negative electrode external terminal.

[0029] The insulating member 500 provides insulation between the cell casing 200 and the external terminal 300. The insulating member 500 has an upper insulating portion 510 and a lower insulating portion 520.

[0030] The upper insulating portion 510 is provided on the upper surface of the top wall 220. The upper insulating portion 510 is interposed between the upper surface of the top wall 220 and the external terminal 300.

[0031] The lower insulating portion 520 is provided on the lower surface of the top wall 220. The lower insulating portion 520 is interposed between the positive electrode current collector plate 410 and the cell case 200.

[0032] Next, a description will be given of a method for manufacturing the energy storage cell 1. This manufacturing method includes a winding step and an end portion fixing step.

[0033] In the winding step, the positive electrode sheet 110 and the negative electrode sheet 120 are wound with the separator 130 interposed therebetween to form the electrode body 100 constituted by a wound body.

[0034] In the terminal end fixing process, the terminal end of the electrode body 100 is fixed. In the terminal end fixing process, the terminal end is adhered to a portion of the electrode body 100 located inside the terminal end with an adhesive layer 134. In this embodiment, the terminal end is composed of an extension 135.

[0035] As described above, in the energy storage cell 1 of this embodiment, the terminal end of the electrode assembly 100 is fixed by the adhesive layer 134 of the separator 130, making it possible to omit tape or the like for fixing the electrode assembly 100. This prevents the stress distribution generated in the electrode assembly 100 when the electrode assembly 100 expands from becoming uneven.

[0036] In the above embodiment, an example is shown in which the adhesive layer 134 is provided over the entire area of ​​the separator layer 132, but the adhesive layer 134 may be provided only on the extension portion 135, or may be provided only on the separator 130 that forms the outermost periphery of the electrode body 100, in a portion that is approximately one-fourth the length of the entire circumference of the separator 130 that forms the outermost periphery from the end of the separator 130.

[0037] As shown in FIG. 4, only the separator 130 disposed on the outermost periphery of the electrode assembly 100 may have an extension 135 .

[0038] 5, the adhesive layer 134 of the separator 130 may have inner adhesive elements 134a provided on the inner surface of the separator layer 132 in the radial direction and outer adhesive elements 134b provided on the outer surface of the separator layer 132 in the radial direction. Note that while Fig. 5 shows an example in which only the separator 130 arranged at the outermost periphery of the electrode body 100 has the extension portion 135, the configuration in which the adhesive layer 134 has the inner adhesive elements 134a and the outer adhesive elements 134b is also applicable to cases in which both of the two separators 130 have the extension portion 135 as in the above embodiment.

[0039] 6 , the thickness of the extension 135 may gradually decrease with increasing distance from the end 119 of the positive electrode sheet 110 and the end 129 of the negative electrode sheet 120. This shape can be formed, for example, by applying a greater tension to the extension 135 than the tension applied to the positive electrode sheet 110, the negative electrode sheet 120, and the separator 130 during the winding process when winding the portion of the electrode body 100 up to the end 119 of the positive electrode sheet 110 and the end 129 of the negative electrode sheet 120.

[0040] Furthermore, in the above embodiment, an example was shown in which the separator 130 was arranged on the outermost periphery of the electrode assembly 100, but an electrode sheet (for example, the negative electrode sheet 120) may also be arranged on the outermost periphery of the electrode assembly 100.

[0041] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0042] [Aspect 1] an electrode body including a positive electrode sheet, a negative electrode sheet, and a separator, the electrode body being configured as a wound body in which the positive electrode sheet and the negative electrode sheet are wound with the separator interposed therebetween; The separator is a separator layer; an adhesive layer provided on at least one of the inner surface and the outer surface of the separator layer in the radial direction of the electrode body, A storage cell, wherein the terminal end of the electrode body is adhered by the adhesive layer to a portion of the electrode body that is located inside the terminal end in the radial direction.

[0043] In this energy storage cell, the terminal end of the electrode assembly is fixed by the adhesive layer of the separator, making it possible to omit tape or other materials used to fix the electrode assembly, thereby preventing uneven stress distribution in the electrode assembly when the electrode assembly expands.

[0044] [Aspect 2] the separator has an extension portion that extends in the circumferential direction of the electrode body longer than the end of the positive electrode sheet and the end of the negative electrode sheet, 2. The energy storage cell of claim 1, wherein the extension is adhered by the adhesive layer to the separator located inside the extension in the radial direction.

[0045] [Aspect 3] 3. The energy storage cell according to claim 2, wherein the thickness of the extension portion gradually decreases with increasing distance from the end of the positive electrode sheet and the end of the negative electrode sheet.

[0046] In this embodiment, the circularity of the electrode body is improved, so that unevenness in the distribution of stress occurring in the electrode body when the electrode body expands is more reliably suppressed.

[0047] [Aspect 4] The adhesive layer is an inner adhesive element provided on an inner surface of the separator layer in the radial direction; and an outer adhesive element provided on an outer surface of the separator layer in the radial direction.

[0048] [Aspect 5] a winding step of winding a positive electrode sheet and a negative electrode sheet with a separator interposed therebetween to form an electrode assembly constituted by a wound body; and a terminal end fixing step of fixing the terminal end of the electrode body, the separator used in the winding step has a separator layer and an adhesive layer provided on at least one of an inner surface and an outer surface of the separator layer in a radial direction of the electrode body, In the end portion fixing step, the end portion is adhered to a portion of the electrode body located inside the end portion by the adhesive layer.

[0049] [Aspect 6] the separator used in the winding step has an extension portion that extends longer in the circumferential direction of the electrode body than the end of the positive electrode sheet and the end of the negative electrode sheet, In the winding step, a tension applied to the extension portion is greater than a tension applied to the positive electrode sheet, the negative electrode sheet, and the separator when winding a portion of the electrode body from an end of the positive electrode sheet to an end of the negative electrode sheet.

[0050] In this embodiment, the thickness of the extensions gradually decreases with increasing distance from the ends of the positive electrode sheet and the negative electrode sheet, improving the circularity of the electrode body and more reliably preventing uneven stress distribution in the electrode body when the electrode body expands.

[0051] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0052] 1 Energy storage cell, 100 Electrode body, 110 Positive electrode sheet, 112 Positive current collector foil, 112a Main region, 112b End region, 114 Positive electrode active material layer, 120 Negative electrode sheet, 122 Negative current collector foil, 122a Main region, 122b End region, 124 Negative electrode active material layer, 130 Separator, 132 Separator layer, 134 Adhesive layer, 134a Inner adhesive element, 134b Outer adhesive element, 200 Cell casing, 210 Cylindrical portion, 220 Top wall, 230 Bottom wall, 300 External terminal, 410 Positive current collector plate, 420 Negative current collector plate, 510 Insulating member.

Claims

[Claim 1] An electrode body comprising a positive electrode sheet, a negative electrode sheet, and a separator, wherein the positive electrode sheet and the negative electrode sheet are wound around the separator, and the electrode body is composed of a wound body. It comprises a cylindrical cell case that houses the electrode body, The aforementioned separator is, Separator layer, The electrode body has an adhesive layer provided on at least one of the inner and outer surfaces of the separator layer in the radial direction, The terminal portion of the electrode body is bonded by the adhesive layer to the portion of the electrode body located inside the terminal portion in the radial direction. The separator has an extension that extends longer than the end of the positive electrode sheet and the end of the negative electrode sheet in the circumferential direction of the electrode body. The extension portion is bonded to the separator located inside the extension portion in the radial direction by the adhesive layer, in a power storage cell.

Images