Energy storage cell

Abstract

To provide a power storage cell capable of suppressing reaction unevenness in an electrode body.SOLUTION: A power storage cell 1 includes an electrode body 100, and a cell case that houses the electrode body. The cell case includes a case body 210 having an opening that opens upward, a lid connected to the case body, and an elastic member 230 disposed between the case body and the electrode body. The elastic member 230 has a central facing portion 234 that faces the central portion of the electrode body, and the central facing portion 234 has a shape that curves convexly in a direction away from the electrode body.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] JP 2011-96485 A discloses a secondary battery including a battery element, a battery case that houses the battery element, and an elastic member disposed between the side surface of the battery element and the battery case. The battery element is held in a state where it is pressed against the battery case by the compressive force of the elastic member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-96485 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the secondary battery described in JP 2011-96485 A, the electrode body expands during charging, etc., causing the surface pressure acting on the electrode body to become non-uniform. This raises the concern that uneven reaction may occur in the electrode body.

[0005] An object of the present disclosure is to provide an electricity storage cell capable of suppressing the occurrence of reaction unevenness in an electrode body. [Means for solving the problem]

[0006] A storage cell according to one aspect of the present disclosure comprises an electrode body and a cell case that houses the electrode body, the cell case having a case body that houses the electrode body and has an opening that opens upward, a lid connected to the case body so as to cover the opening of the case body, and an elastic member arranged between the case body and the electrode body, the elastic member having a central opposing portion that faces a central portion of the electrode body, and the central opposing portion having a shape that is curved so as to be convex in a direction away from the electrode body. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide an electricity storage cell capable of suppressing the occurrence of reaction unevenness in an electrode body. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view illustrating a storage cell according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is an exploded perspective view of the power storage cell shown in FIG. [Diagram 3] FIG. 2 is a cross-sectional view of the storage cell shown in FIG. [Figure 4] 4 is a cross-sectional view of the storage cell taken along a plane different from that of FIG. 3. [Diagram 5] FIG. 4 is an enlarged cross-sectional view of the vicinity of the negative electrode connecting pin. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will now be described with reference to the accompanying drawings, in which the same or corresponding components are designated by the same reference numerals.

[0010] Fig. 1 is a perspective view that shows a schematic diagram of a storage cell according to an embodiment of the present disclosure. Fig. 2 is an exploded perspective view of the storage cell shown in Fig. 1. Fig. 3 is a cross-sectional view of the storage cell shown in Fig. 1. Fig. 4 is a cross-sectional view of the storage cell in a plane different from that in Fig. 3.

[0011] As shown in FIGS. 1 to 4, the energy storage cell 1 includes an electrode assembly 100, a cell case 200, an external terminal 300, a connecting member 400, and an insulating member 500. The electrode assembly 100 includes an electrode body 100, a cell case 200, an external terminal 300, a connecting member 400, and an insulating member 500.

[0012] The electrode assembly 100 has a plurality of unit electrode bodies 111, 112 and an insulating film 120. In this embodiment, the plurality of unit electrode bodies includes two unit electrode bodies 111, 112. Each unit electrode body 111, 112 includes a plurality of tabs, i.e., a plurality of positive electrode tabs 110P and a plurality of negative electrode tabs 110N. The unit electrode bodies 111, 112 have the same structure. Therefore, hereinafter, only the unit electrode body 111 will be described.

[0013] The electrode unit 111 includes a positive electrode sheet, a separator, and a negative electrode sheet. The positive electrode sheet, the negative electrode sheet, and the separator are formed into a long rectangular shape.

[0014] The positive electrode sheet includes a metal foil and a positive electrode composite layer provided on the metal foil. An uncoated portion where the positive electrode composite layer is not formed is formed on the upper long side of the metal foil, and the positive electrode tabs 110P are formed at intervals from each other in the uncoated portion.

[0015] The negative electrode sheet includes a metal foil and a negative electrode composite layer formed on the metal foil. An uncoated portion where the negative electrode composite layer is not formed is formed on the upper long side of the metal foil, and the negative electrode tabs 110N are formed at intervals from each other on the uncoated portion.

[0016] In a state where each sheet is wound, the positive electrode tabs 110P are arranged in the thickness direction (a direction perpendicular to the paper surface in FIG. 3), and the negative electrode tabs 110N are arranged in the thickness direction. The positive electrode tabs 110P and the negative electrode tabs 110N are arranged at intervals in the width direction (a direction perpendicular to both the thickness direction and the height direction).

[0017] The insulating film 120 has a shape that collectively covers the peripheral and bottom surfaces of the plurality of unit electrode bodies 111 and 112 .

[0018] The cell case 200 houses the electrode assembly 100. The cell case 200 also houses an electrolyte (not shown). The cell case 200 is sealed. As shown in FIGS. 2 to 4, the cell case 200 has a case body 210, a lid 220, and an elastic member 230.

[0019] The case body 210 has an opening 211 that opens upward. The case body 210 is made of a metal such as aluminum. The case body 210 has a bottom wall 212 and a peripheral wall 214. The bottom wall 212 is formed in a rectangular, flat plate shape. The peripheral wall 214 stands up from the bottom wall 212. The peripheral wall 214 is formed in a rectangular tube shape. The length of the peripheral wall 214 in the width direction is longer than the length of the peripheral wall 214 in the thickness direction. The length of the peripheral wall 214 in the height direction is longer than the length of the peripheral wall 214 in the thickness direction.

[0020] The lid 220 closes the opening 211 of the case body 210. The lid 220 is connected to the opening 211 by welding or the like. The lid 220 is formed in a flat plate shape. The lid 220 is made of a metal such as aluminum. The lid 220 has a lid body 222 and an inversion plate 224.

[0021] The lid body 222 is connected to the case body 210 by welding or the like. The lid body 222 is formed with a pressure release valve 222a, a liquid injection hole 222b, a sealing member 222c, and a pair of pin insertion holes 222d.

[0022] The pressure release valve 222a is formed in the center of the lid body 222. The pressure release valve 222a is formed to break when the internal pressure of the cell case 200 reaches or exceeds a predetermined pressure. When the pressure release valve 222a breaks, gas within the cell case 200 is released to the outside of the cell case 200 through the pressure release valve 222a, and the internal pressure of the cell case 200 decreases.

[0023] The liquid injection hole 222b is a through hole for injecting an electrolyte into the cell case 200 during the manufacturing process of the energy storage cell 1.

[0024] The sealing member 222c is a member that seals the liquid injection hole 222b. After the electrolyte is injected into the case body 210, the liquid injection hole 222b is sealed with the sealing member 222c.

[0025] The pair of pin insertion holes 222d are formed at an interval from each other in the width direction. Each of the pin insertion holes 222d is a through hole for inserting a connecting pin 420 described later.

[0026] The reversal plate 224 is connected to the lid body 222 by welding or the like. The reversal plate 224 has a shape that is curved so as to be convex from the outside toward the inside of the lid body 222. When the internal pressure of the cell case 200 reaches or exceeds a predetermined pressure, the reversal plate 224 deforms into a shape that is curved so as to be convex from the inside of the cell case 200 toward the outside.

[0027] The elastic member 230 is disposed between the case body 210 and the electrode body 100. The elastic member 230 is made of rubber, resin, or the like. As shown in Figs. 2 and 4, the elastic member 230 is disposed at a position facing the electrode body 100 in the thickness direction. The length of the elastic member 230 in the width direction is set to be equal to or greater than the length of the electrode body 100 in the same direction. However, the length of the elastic member 230 in the width direction may be shorter than the length of the electrode body 100 in the same direction.

[0028] As shown in FIG. 4, the elastic member 230 has a peripheral facing portion 232 and a central facing portion 234 .

[0029] The peripheral facing portion 232 faces the peripheral portion of the electrode assembly 100. The peripheral facing portion 232 is in contact with the peripheral portion of the electrode assembly 100. The thickness of the peripheral facing portion 232 is smaller than the thickness of each of the unit electrode bodies 111,112.

[0030] The central facing portion 234 faces the center of the electrode assembly 100. The central facing portion 234 has a shape that is recessed in a direction away from the electrode assembly 100. More specifically, the central facing portion 234 has a shape that is curved so as to be convex in a direction away from the electrode assembly 100 (outward in the thickness direction). The difference between the minimum thickness of the central facing portion 234 and the thickness of the peripheral facing portion 232 may be set to be 10% or more and 50% or less of the thickness of each unit electrode body 111, 112.

[0031] The external terminal 300 is fixed to the upper surface of the cell case 200. A bus bar (not shown) is connected by welding or the like to the external terminal 300. The external terminal 300 has a positive electrode member 300P and a negative electrode member 300N.

[0032] The positive electrode member 300P is connected by welding or the like to the upper surface of the cell case 200. The positive electrode member 300P has a positive electrode terminal plate 310 and a terminal block 320.

[0033] The positive electrode terminal plate 310 is formed in a rectangular parallelepiped shape and is made of a metal such as aluminum.

[0034] The terminal block 320 is formed in a rectangular parallelepiped shape. The terminal block 320 is made of a metal (such as iron) different from the metal constituting the positive electrode terminal plate 310. The terminal block 320 is connected to the upper surface of the lid body 222 by welding, and the positive electrode terminal plate 310 is connected to the upper surface of the terminal block 320 by welding or the like. In other words, the case body 210 and the lid 220 are electrically connected to the positive electrode terminal plate 310 via the terminal block 320, and are charged with the same polarity as the positive electrode terminal plate 310. Each of the positive electrode terminal plate 310 and the terminal block 320 has a through hole formed therein for inserting a positive electrode connecting pin 420P described later.

[0035] The negative electrode member 300N is connected to the upper surface of the cell case 200 by welding or the like. The negative electrode member 300N is disposed at a distance in the width direction from the positive electrode member 300P. The negative electrode member 300N has a negative electrode terminal plate 330 and an insulating plate 340.

[0036] The negative electrode terminal plate 330 is formed in a substantially rectangular parallelepiped shape. The negative electrode terminal plate 330 is disposed above the reversal plate 224. As shown in Fig. 5, the negative electrode terminal plate 330 has an opposing portion 332 that faces the reversal plate 224. When the internal pressure of the cell case 200 is less than a predetermined pressure (normal), the reversal plate 224 is spaced apart from the opposing portion 332.

[0037] The insulating plate 340 is fixed to the upper surface of the lid 220. The insulating plate 340 holds the negative electrode terminal plate 330. The insulating plate 340 provides insulation between the lid 220 and the negative electrode terminal plate 330. A through hole for inserting a negative electrode connecting pin 420N described below is formed in each of the negative electrode terminal plate 330 and the insulating plate 340. As shown in Figs. 3 and 5, the insulating plate 340 has an exposure opening 342 that exposes the facing portion 332.

[0038] The connecting member 400 connects the plurality of tabs 110P, 110N to the external terminal 300. The connecting member 400 has a current collecting plate 410 and a connecting pin 420.

[0039] The current collector 410 is connected to a plurality of tabs. The current collector 410 includes a positive current collector 410P and a negative current collector 410N.

[0040] The positive electrode current collector 410P is connected to the multiple positive electrode tabs 110P by welding, etc. The positive electrode current collector 410P has a first flat plate portion 411 and a second flat plate portion 412.

[0041] A plurality of positive electrode tabs 110P are connected to the first flat plate portion 411 by ultrasonic welding or the like. Through holes are formed in the first flat plate portion 411. The plurality of positive electrode tabs 110P are connected to the lower surface of the first flat plate portion 411. However, the plurality of positive electrode tabs 110P may be connected to the upper surface of the first flat plate portion 411.

[0042] The second flat plate portion 412 is disposed on the outer side of the first flat plate portion 411 in the width direction. A connecting hole 412h and a fuse portion 412a are formed in the second flat plate portion 412. The fuse portion 412a is configured as a through hole that penetrates the second flat plate portion 412 in the thickness direction. As shown in FIG. 3, a thin portion may be formed between the second flat plate portion 412 and the first flat plate portion 411.

[0043] The negative current collector 410N is connected to a plurality of negative electrode tabs 110N by welding, etc. The configuration of the negative current collector 410N is substantially the same as the configuration of the positive current collector 410P.

[0044] The connecting pins 420 connect the current collector plate 410 and the external terminal 300. The connecting pins 420 include a positive electrode connecting pin 420P and a negative electrode connecting pin 420N.

[0045] The positive electrode connecting pin 420P connects the positive electrode current collector plate 410P and the positive electrode terminal plate 310. The positive electrode connecting pin 420P is formed in a cylindrical shape. The lower end of the positive electrode connecting pin 420P is connected to the second flat plate portion 412 in a state where it is inserted into the connecting hole 412h. The upper end of the positive electrode connecting pin 420P is crimped to the positive electrode terminal plate 310.

[0046] The negative electrode connecting pin 420N connects the negative electrode current collector plate 410N and the negative electrode terminal plate 330. The negative electrode connecting pin 420N is formed in a cylindrical shape. The lower end of the negative electrode connecting pin 420N is connected to the second flat plate portion 412 in a state where it is inserted into the connecting hole 412h. The upper end of the negative electrode connecting pin 420N is crimped to the negative electrode terminal plate 330.

[0047] The insulating member 500 provides insulation between the connecting member 400 and the cell casing 200. The insulating member 500 includes an insulating sheet 510 and an insulator 520.

[0048] The insulating sheet 510 is connected to the lower surface of the lid main body 222. Through holes are formed in the insulating sheet 510 at a portion overlapping the pressure release valve 222a in the height direction, a portion overlapping the liquid injection hole 222b, a portion overlapping each pin insertion hole 222d, and a portion overlapping the reversal plate 224.

[0049] The insulator 520 has a shape that surrounds the connecting pin 420, and provides insulation between the connecting pin 420 and the cell case 200. The insulator 520 has a positive electrode side insulator 520P and a negative electrode side insulator 520N.

[0050] The positive electrode side insulator 520P covers the positive electrode connecting pin 420P. The positive electrode side insulator 520P is formed in a cylindrical shape. The positive electrode side insulator 520P insulates between the positive electrode connecting pin 420P and the lid main body 222.

[0051] The negative electrode side insulator 520N covers the negative electrode connecting pin 420N. The structure of the negative electrode side insulator 520N is the same as the structure of the positive electrode side insulator 520P.

[0052] In the energy storage cell 1 described above, when the internal pressure of the cell case 200 rises to or above the predetermined pressure due to the occurrence of an abnormality in the electrode assembly 100, the reversal plate 224 is reversed (deformed into a curved shape that is convex upward) and comes into contact with the opposing portion 332 of the negative electrode terminal plate 330. As a result, the external terminal 300, the connecting member 400, and the electrode assembly 100 form a closed circuit via the lid 220, and a large current flows through this circuit. Then, the fuse portion 412a formed in the second flat plate portion 412 melts. As a result, the electrical connection between the electrode assembly 100 and the cell case 200 is cut off.

[0053] As described above, in the energy storage cell 1 of this embodiment, the central opposing portion 234 of the elastic member 230 has a shape that is curved so as to be convex in a direction away from the electrode body 100, so that even if the electrode body 100 expands during charging, etc., the surface pressure acting on the electrode body 100 is prevented from becoming uneven. Therefore, the occurrence of uneven reaction to the electrode body 100 is suppressed.

[0054] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0055] [Aspect 1] An electrode body; A cell case that houses the electrode assembly, The cell casing comprises: a case body that houses the electrode body and has an opening that opens upward; a cover connected to the case body so as to close the opening of the case body; an elastic member disposed between the case body and the electrode body, the elastic member has a central facing portion facing a central portion of the electrode body, The central opposing portion has a shape that is curved so as to be convex in a direction away from the electrode body.

[0056] In this energy storage cell, the central opposing portion of the elastic member has a curved shape that is convex in the direction away from the electrode body, so that even if the electrode body expands during charging, the surface pressure acting on the electrode body is prevented from becoming uneven, thereby preventing uneven reaction to the electrode body.

[0057] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered as limiting. The scope of the present invention is indicated by the claims, not by the description of the embodiments above, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0058] 1 storage cell, 100 electrode body, 110N negative electrode tab, 110P positive electrode tab, 111, 112 unit electrode body, 120 insulating film, 200 cell case, 210 case body, 211 opening, 220 lid, 222 lid body, 224 inversion plate, 230 elastic member, 232 peripheral facing portion, 234 central facing portion, 300 external terminal, 300N negative electrode member, 300P positive electrode member, 310 positive electrode terminal plate, 320 terminal block, 330 negative electrode terminal plate, 340 insulating plate, 400 connecting member, 410 current collector, 410N negative electrode current collector, 410P positive electrode current collector, 420 connecting pin, 420N negative electrode connecting pin, 420P positive electrode connecting pin, 422 Covering portion, 422a fuse portion, 500 insulating member, 510 insulating sheet, 520 insulator, 520N negative electrode side insulator, 520P positive electrode side insulator.

Claims

[Claim 1] An electrode body; A cell case that houses the electrode assembly, The electrode body is Two unit electrode bodies; an insulating film having a shape covering the peripheral surfaces and bottom surfaces of the two unit electrode bodies together; The cell casing comprises: a case body that houses the electrode body and has an opening that opens upward; a cover connected to the case body so as to close the opening of the case body; a pair of elastic members disposed between the case body and the electrode body in a thickness direction of the electrode body, a length of each of the elastic members in a width direction perpendicular to both the thickness direction and the up-down direction is set to be equal to or greater than a length of the electrode body in the width direction; Each of the elastic members is a peripheral facing portion facing the peripheral portion of the electrode body when the electrode body is viewed in the thickness direction; a central opposing portion formed inside the peripheral opposing portion and opposing a central portion of the electrode body when the electrode body is viewed in the thickness direction, the central facing portion has a shape recessed in a direction away from the insulating film in the thickness direction, A storage cell, wherein a difference between the minimum thickness at the central facing portion and the thickness at the peripheral facing portion is set to 10% or more and 50% or less of the thickness of each of the unit electrode bodies.

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