Patent Application
20240145871
This nonprovisional application is based on Japanese Patent Application No. 2022-172245 filed on Oct. 27, 2022 with the Japan Patent Office, the entire contents of which are hereby incorporated by reference.
The present disclosure relates to a power storage cell.
Japanese Patent Application Laid-Open No. 2011-96485 discloses a secondary battery including a battery element, a battery case that houses the battery element, and an elastic member disposed between a side surface of the battery element and the battery case. The battery element is held in a state of being pressed against the battery case by the compressive force of the elastic member.
In the secondary battery described in Japanese Patent Application Laid-Open No. 2011-96485, the surface pressure acting on the electrode assembly becomes uneven due to expansion of the electrode assembly during charging or the like. For this reason, there is a concern that reaction unevenness may occur in the electrode assembly.
It is an object of the present disclosure to provide a power storage cell to suppress occurrence of reaction unevenness in an electrode assembly.
A power storage cell according to one aspect of the present disclosure includes: an electrode assembly; and a cell case that accommodates the electrode assembly, wherein the cell case has a case main body that accommodates the electrode assembly, the case main body being provided with an opening that opens upward, a lid connected to the case main body so as to close the opening of the case main body, and an elastic member disposed between the case main body and the electrode assembly, the elastic member has a center-facing portion facing a central portion of the electrode assembly, and the center-facing portion has a shape curved to protrude in a direction away from the electrode assembly.
The foregoing and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when taken in conjunction with the accompanying drawings.
Embodiments of the present disclosure will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.
As shown in
The electrode assembly 100 includes a plurality of unit electrode assemblies 111, 112 and an insulating film 120. In the present embodiment, the plurality of unit electrode assemblies includes two unit electrode assemblies 111 and 112. Each of the unit electrode assemblies 111 and 112 includes a plurality of tabs, that is, a plurality of positive electrode tabs 110P and a plurality of negative electrode tabs 110N. The unit electrode assemblies 111 and 112 have the same structure. Therefore, the unit electrode assembly 111 will be described below.
The unit electrode assembly 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 in a long rectangular shape.
The positive electrode sheet includes a metal foil and a positive electrode composite layer provided on the metal foil. An uncoated portion in which a positive electrode composite layer is not formed is formed in the upper long side portion of the metal foil, and the plurality of positive electrode tabs 110P are formed at intervals in the uncoated portion.
The negative electrode sheet includes a metal foil and a negative electrode composite layer formed on the metal foil. An uncoated portion in which the negative electrode composite layer is not formed is formed in the upper long side portion of the metal foil, and the plurality of negative electrode tabs 110N are formed at intervals in the uncoated portion.
In a state in which each sheet is wound, each positive electrode tab 110P is arranged in the thickness direction (a direction orthogonal to the sheet of
The insulating film 120 has a shape that collectively covers the peripheral surface and the bottom surface of the plurality of unit electrode assemblies 111 and 112.
The cell case 200 houses the electrode assembly 100. The cell case 200 contains an electrolyte solution (not shown). The cell case 200 is sealed. As shown in
The case main body 210 has an opening 211 that opens upward. The case main body 210 is made of metal such as aluminum. The case main body 210 includes a bottom wall 212 and a peripheral wall 214. The bottom wall 212 is formed in a rectangular and flat plate shape. The peripheral wall 214 rises from the bottom wall 212. The peripheral wall 214 is formed in a quadrangular cylindrical 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.
The lid 220 closes the opening 211 of the case main 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 metal such as aluminum. The lid 220 includes a lid main body 222 and an inversion plate 224.
The lid main body 222 is connected to the case main body 210 by welding or the like. The lid main 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.
The pressure release valve 222a is formed at the center of the lid main body 222. The pressure release valve 222a is formed so as to break when the internal pressure of the cell case 200 becomes equal to or higher than a predetermined pressure. When the pressure release valve 222a breaks, the gas in the cell case 200 is released to the outside of the cell case 200 through the pressure release valve 222a, so that the internal pressure of the cell case 200 decreases.
The liquid injection hole 222b is a through hole for injecting the electrolyte solution into the cell case 200 in the manufacturing process of the power storage cell 1.
The sealing member 222c seals the liquid injection hole 222b. After the electrolyte solution is injected into the case main body 210, the liquid injection hole 222b is sealed by the sealing member 222c.
The pair of pin insertion holes 222d are formed at intervals in the width direction. Each pin insertion hole 222d is a through hole through which a coupling pin 420 described later is inserted.
The inversion plate 224 is connected to the lid main body 222 by welding or the like. The inversion plate 224 has a shape curved so as to be convex from the outside toward the inside of the lid main body 222. When the internal pressure of the cell case 200 becomes equal to or higher than a predetermined pressure, the inversion plate 224 is deformed into a curved shape convex from the inside toward the outside of the cell case 200.
The elastic member 230 is disposed between the case main body 210 and the electrode assembly 100. The elastic member 230 is made of rubber, resin, or the like. As shown in
As shown in
The peripheral-edge-facing portion 232 faces the peripheral edge portion of the electrode assembly 100. The peripheral-edge-facing portion 232 is in contact with the peripheral edge portion of the electrode assembly 100. The thickness of the peripheral-edge-facing portion 232 is smaller than the thickness of each of the unit electrode assemblies 111 and 112.
The center-facing portion 234 faces the central portion of the electrode assembly 100. The center-facing portion 234 is recessed in a direction away from the electrode assembly 100. More specifically, the center-facing portion 234 has a shape 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 center-facing portion 234 and the thickness of the peripheral-edge-facing portion 232 may be set to 10% or more and 50% or less of the thickness of each of the unit electrode assemblies 111 and 112.
The external terminal 300 is fixed to the upper surface of the cell case 200. A bus bar (not shown) is connected to the external terminal 300 by welding or the like. The external terminal 300 includes a positive electrode member 300P and a negative electrode member 300N.
The positive electrode member 300P is connected to the upper surface of the cell case 200 by welding or the like. The positive electrode member 300P includes a positive electrode terminal plate 310 and a terminal block 320.
The positive electrode terminal plate 310 is formed in a rectangular parallelepiped shape. The positive electrode terminal plate 310 is made of a metal such as aluminum.
The terminal block 320 is formed in a rectangular parallelepiped shape. The terminal block 320 is made of a metal (e.g., 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 main 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. That is, the case main body 210 and the lid 220 are electrically connected to the positive electrode terminal plate 310 via the terminal block 320, and are charged to the same polarity as the positive electrode terminal plate 310. Each of the positive electrode terminal plate 310 and the terminal block 320 is formed with a through hole through which a positive electrode coupling pin 420P described later is inserted.
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 spaced apart from the positive electrode member 300P in the width direction. The negative electrode member 300N includes a negative electrode terminal plate 330 and an insulating plate 340.
The negative electrode terminal plate 330 is formed in a substantially rectangular parallelepiped shape. The negative electrode terminal plate 330 is disposed above the inversion plate 224. As shown in
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 insulates the lid 220 from the negative electrode terminal plate 330. Each of the negative electrode terminal plate 330 and the insulating plate 340 is formed with a through hole through which a negative electrode coupling pin 420N described later is inserted. As shown in
The coupling member 400 connects the plurality of tabs 110P and 110N to the external terminal 300. The coupling member 400 includes a current collector plate 410 and a coupling pin 420.
The current collector plate 410 is connected to a plurality of tabs. The current collector plate 410 includes a positive electrode current collector plate 410P and a negative electrode current collector plate 410N.
The positive electrode current collector plate 410P is connected to a plurality of positive electrode tabs 110P by welding or the like. The positive electrode current collector plate 410P includes a first flat plate portion 411 and a second flat plate portion 412.
A plurality of positive electrode tabs 110P are connected to the first flat plate portion 411 by ultrasonic welding or the like. A through hole is 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.
The second flat plate portion 412 is disposed outside the first flat plate portion 411 in the width direction. A coupling hole 412h and a fuse portion 412a are formed in the second flat plate portion 412. The fuse portion 412a is formed by a through hole penetrating the second flat plate portion 412 in the thickness direction. As shown in
The negative electrode current collector plate 410N is connected to a plurality of negative electrode tabs 110N by welding or the like. The configuration of the negative electrode current collector plate 410N is substantially the same as the configuration of the positive electrode current collector plate 410P.
The coupling pin 420 connects the current collector plate 410 and the external terminal 300. The coupling pin 420 includes a positive electrode coupling pin 420P and a negative electrode coupling pin 420N.
The positive electrode coupling pin 420P connects the positive electrode current collector plate 410P and the positive electrode terminal plate 310. The positive electrode coupling pin 420P is formed in a cylindrical shape. The lower end portion of the positive electrode coupling pin 420P is connected to the second flat plate portion 412 in a state of being inserted into the coupling hole 412h. The upper end of the positive electrode coupling pin 420P is caulked to the positive electrode terminal plate 310.
The negative electrode coupling pin 420N connects the negative electrode current collector plate 410N and the negative electrode terminal plate 330. The negative electrode coupling pin 420N is formed in a cylindrical shape. The lower end portion of the negative electrode coupling pin 420N is connected to the second flat plate portion 412 in a state of being inserted into the coupling hole 412h. The upper end of the negative electrode coupling pin 420N is caulked to the negative electrode terminal plate 330.
The insulating member 500 insulates the coupling member 400 from the cell case 200. The insulating member 500 includes an insulating sheet 510 and an insulator 520.
The insulating sheet 510 is connected to the lower surface of the lid main body 222. A through hole is formed in a portion of the insulating sheet 510 which overlaps the pressure release valve 222a in the height direction, a portion which overlaps the liquid injection hole 222b, a portion which overlaps the pin insertion hole 222d, and a portion which overlaps the inversion plate 224.
The insulator 520 has a shape surrounding the coupling pin 420, and insulates the coupling pin 420 from the cell case 200. The insulator 520 includes a positive electrode side insulator 520P and a negative electrode side insulator 520N.
The positive electrode side insulator 520P covers the positive electrode coupling pin 420P. The positive electrode side insulator 520P is formed in a cylindrical shape. The positive electrode side insulator 520P insulates the positive electrode coupling pin 420P from the lid main body 222.
The negative electrode side insulator 520N covers the negative electrode coupling pin 420N. The structure of the negative electrode side insulator 520N is the same as the structure of the positive electrode side insulator 520P.
In the power storage cell 1 described above, when the internal pressure of the cell case 200 rises to the predetermined pressure or higher due to the occurrence of an abnormality or the like in the electrode assembly 100, the inversion plate 224 is inverted (deformed into a shape curved to be convex upward) to contact the opposing portion 332 of the negative electrode terminal plate 330. Thus, since the external terminal 300, the coupling member 400, and the electrode assembly 100 form a closed circuit through the lid 220, a large current flows through the circuit. Then, the fuse portion 412a formed in the second flat plate portion 412 is fused. As a result, the electrical connection between the electrode assembly 100 and the cell case 200 is interrupted.
As described above, in the power storage cell 1 according to the present embodiment, since the center-facing portion 234 of the elastic member 230 has a shape which is curved so as to be convex in a direction away from the electrode assembly 100, even when the electrode assembly 100 expands during charging or the like, the surface pressure acting on the electrode assembly 100 is prevented from becoming uneven. Therefore, the generation of the reaction unevenness on the electrode assembly 100 is suppressed.
It will be appreciated by those skilled in the art that the exemplary embodiments described above are specific examples of the following aspects.
A power storage cell comprising:
In this power storage cell, since the center-facing portion of the elastic member is curved so as to be convex in a direction away from the electrode assembly, even when the electrode assembly expands during charging or the like, the surface pressure acting on the electrode assembly is prevented from becoming uneven. Therefore, the generation of the reaction unevenness on the electrode assembly is suppressed.
Although the present disclosure has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the scope of the present disclosure being interpreted by the terms of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-172245 | Oct 2022 | JP | national |
