Power storage cell

Abstract

To improve the insulation quality between a battery case and a terminal of an electrode.SOLUTION: In a power storage cell 100, a case 2 includes a peripheral wall part 2c that is disposed on an outer peripheral side of a wound electrode body 1 and extends in a tubular shape along an axial direction of the wound electrode body 1, and a top plate part 2a that is provided at one end in the axial direction of the peripheral wall part 2c and closes the one end. The top plate part 2a includes a positive electrode terminal 3 existing on an outer side of the case 2 when viewed from a penetration hole 2b communicating between the inside and the outside of the case 2, an external gasket 5 existing between the case 2 and the positive electrode terminal 3 in the axial direction and insulating these from each other, and a rivet part 3b inserted into the penetration hole 2b and connecting the positive electrode terminal 3 and a positive electrode of the wound electrode body 1 to each other. One of a surface of the rivet part 3b, which faces the penetration hole 2b in a radial direction of the wound electrode body 1, and an inner wall of the penetration hole, which faces the rivet part 3b, is covered with an insulating material 40.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] For example, Japanese Patent Laid-Open Publication No. 11-121041 (Patent Document 1) discloses the configuration of a power storage cell in which electrode terminals are provided on a battery case. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-121041 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned storage cell, an insulator or the like is provided to prevent contact between the electrode terminals and the battery case, but it is necessary to further improve such insulation properties in order to suppress deterioration of the performance of the storage cell.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a storage cell that improves the insulation between a battery case and an electrode terminal. [Means for solving the problem]

[0006] A storage cell according to an aspect of the present disclosure includes a wound electrode body including a positive electrode and a negative electrode, and a case that houses the wound electrode body. The case includes a peripheral wall portion disposed on the outer periphery of the wound electrode body and extending in a cylindrical shape along the axial direction of the wound electrode body, and a lid portion provided at one end in the axial direction of the peripheral wall portion and closing the one end. The lid portion is provided with a through hole that communicates the inside and outside of the case. The lid portion includes a positive electrode terminal located on the outer side of the case as viewed from the through hole, an insulating portion located between the case and the positive electrode terminal in the axial direction and insulating them from each other, and a connecting member that is inserted into the through hole and connects the positive electrode terminal and the positive electrode to each other. Either a circumferential surface of the connecting member that faces the through hole in the radial direction of the wound electrode body or an inner wall of the through hole that faces the connecting member is covered with an insulating material.

[0007] In this way, an insulating material is interposed between the surface of the connecting member and the inner wall of the through hole, thereby improving the insulation between the case including the lid portion provided on the peripheral wall portion and the positive terminal connected to the wound electrode body via the connecting member.

[0008] In this embodiment, the insulating material is provided so as to abut against the other of the inner wall of the through hole and the surface of the connecting member.

[0009] In this way, either the surface of the connecting member or the inner wall of the through hole is covered with an insulating material, so that the insulation between the case and the positive terminal can be improved.

[0010] Furthermore, in this embodiment, the insulating material is coated on the circumferential surface of the connecting member to have a predetermined thickness.

[0011] In this way, since the surface of the connecting member is covered with an insulating material, it is possible to improve the insulation between the case and the positive terminal.

[0012] Furthermore, in this embodiment, the insulating material coats the inner wall of the through hole to a predetermined thickness.

[0013] In this way, the inner wall of the through hole is covered with an insulating material, so that the insulation between the case and the positive electrode terminal can be improved. Effect of the Invention

[0014] According to the present disclosure, it is possible to provide an electricity storage cell that improves the insulation between the battery case and the electrode terminals. [Brief description of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing an example of the configuration of a storage cell according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic perspective view showing an example of the configuration of a wound electrode body in the present embodiment. [Diagram 3] FIG. 2 is a plan view showing an example of the configuration of a positive electrode current collector plate in the present embodiment. [Figure 4] FIG. 2 is a plan view showing an example of the configuration of a negative electrode current collector plate in the present embodiment. [Diagram 5] 2 is a partially enlarged view of the vicinity of the positive electrode current collector plate in FIG. 1. [Figure 6] FIG. 11 is a partially enlarged view of the vicinity of a positive electrode current collector plate in a modified example. [Figure 7] FIG. 11 is a partially enlarged view of the vicinity of a positive electrode current collector plate in another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and their description will not be repeated.

[0017] Fig. 1 is a cross-sectional view showing an example of the configuration of an energy storage cell 100 according to the present embodiment. As shown in Fig. 1, the energy storage cell 100 includes a wound electrode body 1, a case 2, a positive electrode terminal 3, a positive electrode current collector 4, an external gasket 5, an internal gasket 6, a negative electrode current collector 7, a polymer ring 8, and a sealing plug 9.

[0018] The wound electrode body 1 is housed in a case 2. The case 2 has a cylindrical shape. The wound electrode body 1 is wound so as to have a cylindrical shape similar to the case 2. In other words, the energy storage cell 100 is a cylindrical battery. The case 2 is made of copper, aluminum, or the like.

[0019] The case 2 includes a top plate portion 2a, a peripheral wall portion 2c, and a sealing plate 2d. The peripheral wall portion 2c is provided on the outer periphery of the wound electrode body 1 and has a cylindrical shape. The top plate portion 2a is connected to the end of the peripheral wall portion 2c on the Z1 side in the Z direction. The top plate portion 2a is formed integrally with the peripheral wall portion 2c. The top plate portion 2a covers (closes) the opening on the Z1 side of the peripheral wall portion 2c. The sealing plate 2d is connected to the end of the peripheral wall portion 2c on the Z2 side in the Z direction. The sealing plate 2d covers (closes) the opening on the Z2 side of the peripheral wall portion 2c. A crimped portion 2e is formed at the end of the peripheral wall portion 2c on the Z2 side, which is crimped to the outer periphery of the sealing plate 2d. The crimped portion 2e is formed in an annular shape. The top plate portion 2a is an example of a "lid portion" in the present disclosure.

[0020] The wound electrode body 1 includes a positive electrode sheet 10, a negative electrode sheet 20, and a separator 30. The separator 30 is provided between the positive electrode sheet 10 and the negative electrode sheet 20. The separator 30 separates the positive electrode sheet 10 and the negative electrode sheet 20 while allowing ions (e.g., lithium ions) to move between the positive electrode sheet 10 (positive electrode active material) and the negative electrode sheet 20 (negative electrode active material). The wound electrode body 1 is composed of an electrode plate group in which the positive electrode sheet 10 and the negative electrode sheet 20 are wound with the separator 30 interposed therebetween.

[0021] The positive electrode sheet 10 includes a positive electrode current collector 11 and a positive electrode mixture layer 12. The positive electrode mixture layer 12 is applied to both radially opposite surfaces of the positive electrode current collector 11 (more specifically, the positive electrode coated portion 11a). The positive electrode mixture layer 12 is in close contact with the separator 30.

[0022] Positive electrode current collector 11 is made of, for example, aluminum. Positive electrode mixture layer 12 is formed by applying a positive electrode slurry to the surface of positive electrode current collector 11 and drying it. The positive electrode slurry is a slurry prepared by kneading materials for positive electrode mixture layer 12 (such as a positive electrode active material and a binder) and a solvent.

[0023] Positive electrode current collector 11 includes positive electrode coated portion 11a and positive electrode uncoated portion 11b. Positive electrode coated portion 11a is a portion of positive electrode current collector 11 that is coated with positive electrode composite layer 12 (an unexposed portion).

[0024] The positive electrode uncoated portion 11b is an exposed portion of the positive electrode current collector 11 that is not covered by the positive electrode mixture layer 12. The positive electrode uncoated portion 11b is located closer to the Z1 side than the positive electrode coated portion 11a. Specifically, the positive electrode uncoated portion 11b protrudes from the positive electrode coated portion 11a to the Z1 side.

[0025] The positive electrode uncoated portion 11b is bent radially inward by contacting the positive electrode current collector 4 arranged on the Z1 side. As a result, the positive electrode current collector 4 is positively charged. The positive electrode uncoated portion 11b is joined to the positive electrode current collector 4 by welding.

[0026] The negative electrode sheet 20 includes a negative electrode current collector 21 and a negative electrode mixture layer 22. The negative electrode mixture layer 22 is applied to both radially opposite surfaces of the negative electrode current collector 21 (more specifically, the negative electrode coated portion 21a). The negative electrode mixture layer 22 is in close contact with the separator 30.

[0027] The negative electrode current collector 21 is made of, for example, copper. The negative electrode mixture layer 22 is formed by applying a negative electrode slurry to the surface of the negative electrode current collector 21 and drying it. The negative electrode slurry is a slurry prepared by kneading the materials of the negative electrode mixture layer 22 (negative electrode active material, binder, etc.) and a solvent.

[0028] The negative electrode current collector 21 includes a negative electrode coated portion 21a and a negative electrode uncoated portion 21b. The negative electrode coated portion 21a is a portion of the negative electrode current collector 21 that is coated with the negative electrode composite layer 22 (an unexposed portion).

[0029] The negative electrode uncoated portion 21b is an exposed portion of the negative electrode current collector 21 that is not covered by the negative electrode composite layer 22. The negative electrode uncoated portion 21b is located on the Z2 side of the negative electrode coated portion 21a. Specifically, the negative electrode uncoated portion 21b protrudes from the negative electrode coated portion 21a to the Z2 side.

[0030] The negative electrode uncoated portion 21b is bent radially inward by contacting the negative electrode current collector 7 arranged on the Z2 side. As a result, the negative electrode current collector 7 is negatively charged. The negative electrode uncoated portion 21b is joined to the negative electrode current collector 7 by welding.

[0031] Fig. 2 is a schematic perspective view showing an example of the configuration of the wound electrode body 1 in this embodiment. As shown in Fig. 2, the wound electrode body 1 is formed by winding a positive electrode sheet 10, a negative electrode sheet 20, and a separator 30 so as to surround the periphery of a winding axis line α. In Fig. 2, for the sake of convenience, the wound electrode body 1 is shown in a slightly unwound state so that the wound state of the wound electrode body 1 can be easily understood.

[0032] 1 again, the positive electrode terminal 3 includes a disk portion 3a and a rivet portion 3b. The disk portion 3a is provided outside the case 2 and is thus exposed. The rivet portion 3b is connected to the disk portion 3a. The rivet portion 3b is provided so as to extend from the center of the disk portion 3a toward the Z2 side. The positive electrode terminal 3 is made of aluminum. The rivet portion 3b is an example of a "connecting member" of the present disclosure.

[0033] The disk portion 3a is disposed on a top plate portion 2a of the case 2. The top plate portion 2a is provided so as to be perpendicular to the Z direction. The top plate portion 2a is provided with a through hole 2b (see FIG. 5) that communicates the inside and outside of the case 2. The rivet portion 3b extends from the disk portion 3a, which is disposed on the outside of the case 2, through the through hole 2b to the inside of the case 2. The Z direction is an example of the "axial direction" in this disclosure.

[0034] The positive electrode current collector 4 is housed in the case 2. The positive electrode current collector 4 (a piece 4d described below) is welded to the positive electrode uncoated portion 11b of the positive electrode sheet 10. As a result, the positive electrode current collector 4 is positively charged. The positive electrode current collector 4 is welded to the end 3c on the Z2 side of the rivet portion 3b. As a result, the positive electrode terminal 3 is positively charged.

[0035] The external gasket 5 is provided on the outside of the case 2. Specifically, the external gasket 5 is disposed between the disk portion 3a of the positive terminal 3 and the top plate portion 2a of the case 2. This provides insulation between the positive terminal 3 and the case 2. The external gasket 5 is an example of an "insulating portion" of the present disclosure.

[0036] The internal gasket 6 is provided inside the case 2. Specifically, the internal gasket 6 is disposed between the case 2 and the positive current collector plate 4. This insulates the case 2 from the positive current collector plate 4. The rivet portion 3b penetrates the internal gasket 6 and comes into contact with the positive current collector plate 4.

[0037] The negative electrode current collector 7 is housed in the case 2. The negative electrode current collector 7 (a piece 7d described below) is welded to a negative electrode uncoated portion 21b (described below) of the negative electrode sheet 20. As a result, the negative electrode current collector 7 is negatively charged. The negative electrode current collector 7 is in contact with the case 2. As a result, the case 2 is negatively charged.

[0038] The polymer ring 8 is provided between the outer peripheral edge of the sealing plate 2d and the crimped portion 2e formed on the peripheral wall portion 2c. The polymer ring 8 has an annular shape.

[0039] A through hole 2f provided in the center of the sealing plate 2d is closed by the sealing plug 9. The sealing plug 9 is provided so as to penetrate through a through hole 7g provided in the center of the negative electrode current collector plate 7 as well as through hole 2f.

[0040] Fig. 3 is a plan view showing an example of the configuration of the positive current collector 4 in the present embodiment. As shown in Fig. 3, the positive current collector 4 has a disk shape. The positive current collector 4 includes a central portion 4a, spokes 4b, an outer peripheral edge portion 4c, and a piece portion 4d.

[0041] The central portion 4a is provided at the center of the positive current collector plate 4. The rivet portion 3b is joined to the central portion 4a. The spokes 4b are provided so as to extend radially outward from the central portion 4a. Six spokes 4b are provided at equal angular intervals around the central portion 4a of the positive current collector plate 4.

[0042] The outer peripheral edge portion 4c is provided on the outer peripheral edge of the positive current collector plate 4. Each of the six spokes 4b connects the outer peripheral edge portion 4c and the central portion 4a. The spokes 4b are formed to bend in the Z direction. Note that the central portion 4a of the positive current collector plate 4 moves (displaces) the largest in the Z direction.

[0043] Between the spokes 4b adjacent in the circumferential direction, a through hole 4e is formed. That is, six through holes 4e are formed. A piece portion 4d is provided inside each of the six through holes 4e. Each of the six pieces 4d is connected to the outer circumferential edge portion 4c by a connecting portion 4f. Each of the six pieces 4d has a tapered shape toward the inside in the radial direction.

[0044] Fig. 4 is a plan view showing an example of the configuration of the negative current collector 7 in the present embodiment. As shown in Fig. 3, the negative current collector 7 has a disk shape. The negative current collector 7 includes a central portion 7a, spokes 7b, an outer peripheral edge portion 7c, and a piece portion 7d.

[0045] The central portion 7a is provided at the center of the negative current collector 7. The spokes 7b are provided so as to extend radially outward from the central portion 7a. Six spokes 7b are provided at equal angular intervals around the central portion 7a of the negative current collector 7.

[0046] The outer peripheral edge portion 7c is provided on the outer peripheral edge of the negative electrode current collector plate 7. Each of the six spokes 7b connects the outer peripheral edge portion 7c and the central portion 7a. Each spoke 7b is formed to bend in the Z direction. Of the negative electrode current collector plate 7, the outer peripheral edge portion 7c moves (displaces) the largest in the Z direction.

[0047] Between the spokes 7b adjacent to each other in the circumferential direction, a through hole 7e is formed. That is, six through holes 7e are formed. The pieces 7d are provided at positions corresponding to the six through holes 7e. Specifically, each of the six pieces 7d is disposed inside the corresponding through hole 7e. Each of the six pieces 7d is connected to the central portion 7a by a connecting portion 7f. Each of the six pieces 7d has a shape tapered toward the inside in the radial direction.

[0048] In the energy storage cell 100 having the above-described configuration, an insulating external gasket 5 is provided to prevent contact between the positive terminal 3 and the case 2. However, in order to prevent a decrease in the performance of the energy storage cell 100, it is necessary to further improve the insulation between the positive terminal 3 and the case 2.

[0049] Therefore, in this embodiment, either the surface of the rivet portion 3b facing the through hole 2b in the radial direction of the wound electrode body 1 or the inner wall of the through hole 2b facing the rivet portion 3b is covered with an insulating material.

[0050] In this way, an insulating material is interposed between the surface of the rivet portion 3b and the inner wall of the through hole 2b, thereby improving the insulation between the case 2 including the top plate portion 2a provided on the peripheral wall portion 2c and the positive electrode terminal 3 connected to the wound electrode body 1 via the rivet portion 3b.

[0051] Hereinafter, a more detailed description will be given with reference to Figs. 1 and 5. Fig. 5 is a partially enlarged view of the vicinity of the positive electrode current collector plate 4 in Fig. 1. As shown in Figs. 1 and 5, in this embodiment, a hollow cylindrical insulating material 40 is provided so as to cover the entire circumference around the axis of the rivet portion 3b of the positive electrode terminal 3. The hollow cylindrical insulating material 40 is provided so as to penetrate the external gasket 5, the top plate portion 2a, and the internal gasket 6. Furthermore, the outer peripheral portion of the hollow cylindrical insulating material 40 abuts against the inner wall of the through hole of the external gasket 5, the inner wall of the through hole 2b of the top plate portion 2a, and the inner wall of the through hole of the internal gasket 6. The end portion 3c of the rivet portion 3b is welded to the positive electrode current collector plate 4.

[0052] The insulation between the rivet portion 3b and the inner wall of the through hole 2b (i.e., the top plate portion 2a) is improved by covering the entire circumference of the rivet portion 3b around the axis with the insulating material 40. This improves the insulation between the positive terminal 3 and the case 2. The insulating material may be any known material having insulating properties, and is not particularly limited. For example, various resins such as silicon, ceramics, etc. may be used. The insulating material 40 is pre-coated on the rivet portion 3b so as to have a predetermined hollow cylindrical shape. For example, in a state where the internal gasket 6 and the positive electrode current collector plate 4 are provided inside the top plate portion 2a and the external gasket 5 is provided outside the top plate portion 2a, the rivet portion 3b of the positive electrode terminal 3 is provided so as to penetrate the through hole of the external gasket 5, the through hole 2b, and the through hole of the internal gasket 6 in a state where the insulating material 40 is covered all around. Then, the end portion 3c of the rivet portion 3b is welded to the positive electrode current collector plate 4.

[0053] As described above, in the energy storage cell 100 according to this embodiment, the insulating material 40 is interposed between the surface of the rivet portion 3b and the inner wall of the through hole 2b, so that it is possible to improve the insulation between the case 2 including the top plate portion 2a provided on the peripheral wall portion 2c and the positive electrode terminal 3 connected to the wound electrode body 1 via the rivet portion 3b. Therefore, it is possible to provide an energy storage cell that improves the insulation between the battery case and the electrode terminal.

[0054] Modifications will be described below. In the above-described embodiment, an example has been described in which the insulating material 40 is configured to be coated in advance around the entire circumference of the rivet portion 3b. However, for example, a configuration may be used in which a gap is formed around the entire axis of the rivet portion 3b and the insulating material 40 is injected into the gap to coat the rivet portion 3b, or a configuration may be used in which the entire circumference of the inner wall of the through hole 2b is coated in advance with the insulating material 40 in a ring shape and the rivet portion 3b is inserted into the inner through hole formed by the insulating material 40.

[0055] Furthermore, in the above-described embodiment, it has been described that of the surface of the rivet portion 3b and the inner wall of the through hole 2b, the rivet portion 3b is covered with the insulating material 40 and is arranged so that the insulating material 40 abuts against the inner wall of the through hole 2b. However, it is sufficient that at least one of the surface of the rivet portion 3b and the inner wall of the through hole 2b is covered with the insulating material 40, and it is not necessary that the insulating material 40 abuts against the other.

[0056] For example, the circumferential surface of the rivet portion 3b may be covered with an insulating member having a predetermined thickness. The predetermined thickness is adapted, for example, by experiments or the like so as to ensure insulation between the rivet portion 3b and the inner wall of the through hole 2b. FIG. 6 is a partially enlarged view of the vicinity of the positive electrode current collector plate 4 in the modified example. As shown in FIG. 6, instead of the insulating material 40 in FIG. 1, the circumferential surface of the rivet portion 3b may be covered with a hollow cylindrical insulating material 41 having a predetermined thickness, and a hollow cylindrical gasket 42 may be provided to fill the gap between the insulating material 41 and the inner wall of the through hole 2b. Even in this way, the insulation between the positive electrode terminal 3 and the case 2 can be improved.

[0057] Alternatively, the inner wall of the through hole 2b may be covered with an insulating member having a predetermined thickness. Fig. 7 is a partial enlarged view of the vicinity of the positive electrode current collector plate 4 in another modified example. As shown in Fig. 7, instead of the insulating material 40 in Fig. 1, the inner wall of the through hole 2b may be covered with a hollow cylindrical insulating material 43 having a predetermined thickness, and a hollow cylindrical gasket 44 may be provided so as to fill the gap between the inner peripheral portion of the insulating material 43 and the surface of the rivet portion 3b. In this way, the insulation between the positive electrode terminal 3 and the case 2 can be improved.

[0058] The above-described modified examples may be implemented in whole or in part in appropriate combination. The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0059] 1 wound electrode body, 2 case, 2a top plate portion, 2b, 2f, 4e, 7e, 7g through holes, 2c peripheral wall portion, 2d sealing plate, 2e crimping portion, 3 positive electrode terminal, 3a disk portion, 3b rivet portion, 3c end portion, 4 positive electrode current collector, 4a, 7a center portion, 4b, 7b spokes, 4c, 7c outer peripheral edge portion, 4d, 7d piece portion, 4f, 7f connection portion, 5 external gasket, 6 internal gasket, 7 negative electrode current collector, 8 polymer ring, 9 sealing plug, 10 positive electrode sheet, 11 positive electrode current collector, 11a positive electrode coated portion, 11b positive electrode uncoated portion, 12 positive electrode composite layer, 20 negative electrode sheet, 21 negative electrode current collector, 21a negative electrode coated portion, 21b Negative electrode uncoated portion, 22 negative electrode composite layer, 30 separator, 40, 41, 43 insulating material, 42, 44 gasket, 100 storage cell.

Claims

1. A wound electrode body including a positive electrode and a negative electrode; A case that houses the wound electrode body, The case is a peripheral wall portion disposed on an outer circumferential side of the wound electrode body and extending in a cylindrical shape along an axial direction of the wound electrode body; a cover portion provided at one end of the peripheral wall portion in an axial direction and closing the one end, The lid portion is provided with a through hole that communicates between the inside and the outside of the case, The lid portion is a positive electrode terminal located on an outer side of the case as viewed from the through hole; an insulating portion located between the case and the positive electrode terminal in the axial direction to insulate them from each other; a connecting member that is inserted into the through hole and connects the positive electrode terminal and the positive electrode to each other, a circumferential surface of the connecting member that faces the through hole in the radial direction of the wound electrode body, and an inner wall of the through hole that faces the connecting member, are covered with an insulating material.

2. The energy storage cell according to claim 1 , wherein the insulating material is provided so as to abut against the other of an inner wall of the through hole and a surface of the connecting member.

3. The energy storage cell according to claim 1 , wherein the insulating material is coated on a circumferential surface of the connecting member so as to have a predetermined thickness.

4. The energy storage cell according to claim 1 , wherein the insulating material is coated on an inner wall of the through hole to have a predetermined thickness.

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