Energy storage cell

Abstract

To provide a power storage cell capable of suppressing heat generation of an inversion plate.SOLUTION: A power storage cell 1 includes an electrode body, a cell case, and an external terminal 300. The cell case has a case body and a lid. The lid has a lid body 222 and an inversion plate 224 that is able to short-circuit between the lid body and the external terminal. The inversion plate 224 includes: a base portion 224; an inversion portion 224b connected to the inside of the base portion and capable of contacting the external terminal; and a low elastic member 224c made of a conductive material having an elastic modulus smaller than that of the inversion portion and provided on a surface, of the inversion portion, facing the external terminal. The low elastic member 224c is elastically deformed by being sandwiched between the inversion portion and the external terminal during the inversion of the inversion portion.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] Japanese Patent Application Laid-Open No. 2017-174732 discloses a storage cell including an electrode assembly and a case that houses the electrode assembly. The case has a body and a lid fixed to the body. An inversion plate is connected to the lid. The lid is electrically connected to an external terminal of a positive electrode, and the inversion plate is electrically connected to the lid. A conductive plate electrically connected to an external terminal of a negative electrode is disposed above the inversion plate.

[0003] When the reversal plate in the above-mentioned storage cell is reversed, the reversal plate comes into contact with the current-carrying plate, and the positive and negative external terminals are short-circuited via the current-carrying plate, the reversal plate, and the lid, causing a short-circuit current to flow through the reversal plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-174732 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the energy storage cell described in JP 2017-174732 A, if the contact area between the reversal plate and the conduction plate is small, there is a concern that the reversal plate will generate heat.

[0006] An object of the present disclosure is to provide an energy storage cell capable of suppressing heat generation in the reversal plate. [Means for solving the problem]

[0007] a low-elasticity member made of a conductive material having a smaller elastic modulus than the elastic modulus of the inversion portion and provided on a surface of the inversion portion facing the external terminal, the low-elasticity member being elastically deformed by being sandwiched between the inversion portion and the external terminal when the inversion portion is inverted; Effect of the Invention

[0008] According to the present disclosure, it is possible to provide an energy storage cell capable of suppressing heat generation in the reversal plate. [Brief description of the drawings]

[0009] [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] FIG. 2 is an enlarged cross-sectional view of the vicinity of the reversal plate. [Diagram 5] FIG. 11 is a cross-sectional view illustrating a schematic state of the reversal plate after operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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.

[0011] 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.

[0012] As shown in FIGS. 1 to 3, 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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).

[0018] 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 .

[0019] 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. The cell case 200 has a case body 210 and a lid 220.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The reversible plate 224 is connected to the lid body 222 by welding or the like. The reversible plate 224 is capable of short-circuiting the lid body 222 and the external terminal 300. As shown in Fig. 4, the reversible plate 224 has a base portion 224a, a reversible portion 224b, and a low-elasticity member 224c.

[0028] The base 224a is connected to the lid body 222 by welding or the like. In this embodiment, the base 224a is connected to a portion of the lid body 222 that is located below a negative electrode terminal plate 330 (described later). The base 224a is formed in an annular shape, more specifically, in a circular ring shape.

[0029] Inverted portion 224b is connected to the inside of base portion 224a. As shown in Fig. 4, inverted portion 224b has a shape that is curved so as to be convex from the outside to the inside (lower side in Fig. 4) of lid main body 222 when the internal pressure of cell case 200 is less than a predetermined pressure (normal). When the internal pressure of cell case 200 becomes equal to or greater than a predetermined pressure, inverted portion 224b deforms into a shape that is curved so as to be convex from the inside to the outside (upper side in Fig. 4) of cell case 200, as shown in Fig. 5. Inverted portion 224b is made of aluminum, iron, or the like.

[0030] The low elasticity member 224c is made of a conductive material having a modulus of elasticity smaller than that of the inverted portion 224b. The low elasticity member 224c is provided on the surface of the inverted portion 224b facing the negative electrode terminal plate 330 (the upper surface in FIG. 4). When the inverted portion 224b is inverted, the low elasticity member 224c is sandwiched between the inverted portion 224b and the negative electrode terminal plate 330, and is elastically deformed. The low elasticity member 224c is made of, for example, tin plating, conductive rubber, or conductive resin. The thickness of the low elasticity member 224c may be formed to be equal to or smaller than the thickness of the inverted portion 224b, or may be formed to be larger than the thickness of the inverted portion 224b. For example, the thickness of the low elasticity member 224c is set to be about 5 μm to 500 μm.

[0031] As shown in FIG. 4, the length Lc from the edge 224c1 of the low elastic member 224c to the central axis L of the inverted portion 224b may be set to half or more of the length Lb from the edge to the central axis L of the inverted portion 224b in the width direction.

[0032] 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.

[0033] 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.

[0034] The positive electrode terminal plate 310 is formed in a rectangular parallelepiped shape and is made of a metal such as aluminum.

[0035] 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.

[0036] 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.

[0037] 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. 4, the negative electrode terminal plate 330 has a facing portion 332 facing the reversal plate 224. The facing portion 332 is formed flat. As described above, when the internal pressure of the cell case 200 is less than a predetermined pressure (normal), the reversal portion 224b of the reversal plate 224 is separated from the facing portion 332, whereas when the internal pressure of the cell case 200 is equal to or greater than the predetermined pressure, the reversal portion 224b is deformed to be convex toward the facing portion 332. This causes the low elastic member 224c to come into contact with the facing portion 332.

[0038] 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 4, the insulating plate 340 has an exposure opening 342 that exposes the facing portion 332.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] In the energy storage cell 1 described above, when the internal pressure of the cell case 200 rises to or exceeds the predetermined pressure due to the occurrence of an abnormality in the electrode assembly 100, as shown in FIG. 5, the inverted portion 224b of the inverted plate 224 inverts (deforms into a curved shape that is convex upward), and the low-elasticity member 224c 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 interrupted.

[0054] Here, when the reversal portion 224b is reversed, the low elasticity member 224c is sandwiched between the opposing portion 332 and the reversal portion 224b and elastically deforms, so that the contact area between the reversal plate 224 and the negative electrode terminal plate 330 is effectively secured. Therefore, heat generation at the contact portion between the reversal plate 224 and the negative electrode terminal plate 330 is reduced.

[0055] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0056] [Aspect 1] An electrode body; A cell case that accommodates the electrode assembly; an external terminal fixed to an upper surface of the cell case; The cell casing comprises: 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 close the opening of the case body, The lid is A lid body connected to the opening of the case body and charged to the positive or negative electrode of the electrode body; an inversion plate connected to the lid body and capable of short-circuiting the lid body and the external terminal; The inversion plate is a base portion connected to a portion of the lid body that is located below the external terminal and formed in an annular shape; an inverted portion connected to an inside of the base portion and capable of contacting the external terminal; a low elasticity member made of a conductive material having an elastic modulus smaller than that of the inverted portion and provided on a surface of the inverted portion facing the external terminal; the low-elasticity member is sandwiched between the inverted portion and the external terminal when the inverted portion is inverted, and thereby elastically deforms.

[0057] In this energy storage cell, the low elasticity portion elastically deforms when the reversal portion is reversed, so that the contact area between the reversal plate and the external terminal is effectively secured, thereby suppressing heat generation in the reversal portion.

[0058] [Aspect 2] 2. The energy storage cell of claim 1, wherein the low-elasticity member is made of tin plating.

[0059] 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]

[0060] 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, 224a base, 224b inversion portion, 224c low elasticity member, 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

1. An electrode body; A cell case that accommodates the electrode assembly; an external terminal fixed to an upper surface of the cell case; an insulating sheet provided within the cell case; The cell casing comprises: 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 close the opening of the case body, The lid is A lid body connected to the opening of the case body and charged to the positive or negative electrode of the electrode body; an inversion plate connected to the lid body and capable of short-circuiting the lid body and the external terminal; The inversion plate is a base portion connected to a portion of the lid body that is located below the external terminal and formed in an annular shape; an inverting portion that is connected to the inside of the base portion, has a shape that is curved so as to be convex in a direction away from the external terminal when the internal pressure of the cell case is less than a predetermined pressure, and is invertible so as to be curved so as to be convex toward the external terminal when the internal pressure of the cell case becomes equal to or greater than the predetermined pressure; a low elasticity member made of a conductive material having an elastic modulus smaller than that of the inverted portion and provided on a surface of the inverted portion facing the external terminal; the low-elasticity member is sandwiched between the inverted portion and the external terminal when the inverted portion is inverted, and is elastically deformed; The external terminal is a positive electrode member connected to an upper surface of the lid; a negative electrode member connected to a portion of the upper surface of the lid that is spaced apart from the positive electrode member, The insulating sheet is connected to a lower surface of the lid body, A through hole is formed in the insulating sheet at a portion overlapping the inversion plate in a height direction, a length of the through hole in an arrangement direction in which the positive electrode member and the negative electrode member are arranged is smaller than a length of the low-elasticity member in the arrangement direction.

2. The energy storage cell according to claim 1 , wherein the low elasticity member is made of tin plating.

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