Power storage device

Abstract

To suppress damage to parts other than specific areas even when the internal pressure of an outer shell increases.SOLUTION: In a power storage device 10, a plurality of resin frames 30 are stacked to form an outer shell portion 18, and a plurality of storage cells 12 are stacked and housed within the outer shell portion 18. In addition, in the power storage device 10, a concave portion 36 is provided only in a wall portion 32A of the resin frame 30 forming a side wall 34A. Therefore, in the power storage device 10, when the internal pressure of the outer shell portion 18 increases, the inner wall portion 38A of the resin frame 30 is damaged, thereby suppressing the increase in internal pressure, and further, when the internal pressure increases, the outer wall portion 38B of the resin frame 30 is damaged. As a result, in the power storage device 10, even when the internal pressure of the outer shell portion 18 increases, damage to side walls other than the side wall 34A is suppressed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an electricity storage device. [Background technology]

[0002] As an electricity storage device, a bipolar type electricity storage device is known which includes a bipolar electrode in which a positive electrode active material layer is formed as a positive electrode layer on one surface of a current collector and a negative electrode active material layer is formed as a negative electrode layer on the other surface.

[0003] In the electricity storage device of Patent Document 1, a spacer made of a rubber-based resin is used to maintain the distance between the current collectors of adjacent bipolar electrodes, and multiple current collectors are held in a case. In Patent Document 2, a spacer is placed between an electrode stack in which bipolar electrodes and separators are alternately stacked, and a mold that contains the electrode stack, so that the thickness of the electrode stack is the standard thickness of the electrode stack.

[0004] In secondary batteries such as these power storage devices, gas may be generated inside the case. If gas is generated and accumulates inside the case of the power storage device, pressure will increase, causing changes in the spacing between the current collectors serving as electrodes and deformation.

[0005] Furthermore, if the internal pressure of the case increases due to gas generated inside the case and exceeds the pressure resistance of the case, the case will be damaged. The location of damage in the case is often affected by variations in pressure resistance during manufacturing, making it difficult to identify the location where damage will occur. For this reason, it is difficult to predict the impact of case damage. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-049794 A [Patent Document 2] JP 2020-119669 A Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present disclosure is to provide an electricity storage device in which, if the internal pressure of an outer shell portion increases, damage occurs only in a specific portion. [Means for solving the problem]

[0008] One embodiment of an energy storage device for achieving the above-mentioned object includes a stack in which, when a plurality of electrode layers are stacked in one direction, electrode layers having opposite polarities are provided on one side and the other side of an electrolyte layer, and a current collector is disposed on the side of each of the electrode layers opposite the electrolyte layer, a frame body provided for each of the electrode layers and containing the electrode layers inside a rectangular frame shape, and stacked in the one direction to form an outer shell, and a pressure adjustment unit formed on one side of the frame body for making the withstand pressure of an inner wall of the one side lower than the withstand pressure of the inner walls of the other three sides against pressure from inside the frame body.

[0009] In the electricity storage device of this embodiment, a plurality of laminates are laminated in one direction. In each of the laminates, electrode layers having mutually different polarities are provided on one side and the other side of an electrolyte layer, and a current collector is disposed on the side of each of the electrode layers opposite to the electrolyte layer.

[0010] The outer shell is formed by stacking a plurality of rectangular frame bodies, each of which has an electrolyte layer disposed on one side along the stacking direction and a current collector disposed on the other side, and houses an electrode layer between the electrolyte and the current collector.

[0011] Here, the frame has a pressure adjusting section formed on one side. The pressure adjusting section makes the withstand pressure of the inner wall of the one side lower than the withstand pressure of the inner walls of the other three sides against pressure from inside the frame. As a result, even if the internal pressure in the outer shell increases, damage will occur in the area where the pressure adjusting section is provided, and damage to other areas can be suppressed. Effect of the Invention

[0012] According to the present disclosure, even if the internal pressure in the outer shell increases, the damage can be limited to the area where the pressure adjustment unit is provided. This has the effect of preventing damage to unpredictable areas and preventing damage to the outer shell from affecting the surrounding area. [Brief description of the drawings]

[0013] [Figure 1] 1 is a perspective view showing an outline of a power storage device according to an embodiment of the present invention; [Diagram 2] 2 is a cross-sectional view showing an outline of a main part of the electricity storage device. [Diagram 3] FIG. 2 is a perspective view showing an outline of a main part of the power storage device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, the power storage device of the present disclosure will be described in detail with reference to the drawings. The disclosed energy storage device 10 includes a plurality of energy storage cells 12 as an electrode body, and in the energy storage device 10, the plurality of energy storage cells 12 are stacked in one direction and housed in an outer shell portion 18 having a substantially rectangular box shape (substantially rectangular when viewed from the outside) as a case.

[0015] Fig. 1 shows a perspective view of a main part of an energy storage device 10 according to this embodiment, and Fig. 2 shows a cross-sectional view of the main part of the energy storage device 10 cut along the stacking direction. Fig. 3 shows a perspective view of a main part of an energy storage cell 12. In the drawing, the direction along the stacking direction of the energy storage cell 12 is indicated by arrow A.

[0016] 2, in the power storage device 10, a bipolar electrode 14 is formed between two power storage cells 12 adjacent in the stacking direction, and the power storage device 10 is of a bipolar type (two-pole type). For example, a lithium ion secondary battery or a nickel-metal hydride secondary battery can be used for this type of power storage device 10.

[0017] In the energy storage device 10, the energy storage cell 12 includes an electrode stack 16, which includes a separator 20 as an electrolyte layer, a positive electrode layer 22 as a positive electrode layer, and a negative electrode layer 24 as a negative electrode layer. In the electrode stack 16, the positive electrode layer 22 is disposed on one side of the separator 20 in the stacking direction, and the negative electrode layer 24 is disposed on the other side of the stacking direction, and the electrode stack 16 includes the positive electrode layer 22, the separator 20, and the negative electrode layer 24 stacked in this order.

[0018] In the electric storage cell 12, current collectors 26 are disposed on both sides of the electrode stacking direction in the electrode stack 16, and the electric storage cell 12 has a configuration in which the current collector 26, the positive electrode layer 22, the separator 20, the negative electrode layer 24, and the current collector 26 are stacked in this order. Therefore, between the electric storage cells 12 adjacent in the stacking direction, the positive electrode layer 22 is provided on one surface of the current collector 26, and the negative electrode layer 24 is provided on the other surface.

[0019] A conductive metal material such as Al, SUS, Ni, or Cu is used for the current collector 26. The positive electrode layer 22 is formed on one surface of the current collector 26 by applying a known positive electrode active material to the surface so as to have a required thickness, and the negative electrode layer 24 is formed on the other surface of the current collector 26 (the surface opposite to the positive electrode layer 22) by applying a known negative electrode active material to the surface so as to have a required thickness.

[0020] As a result, in the bipolar electrode 14 formed by the power storage cells 12 adjacent in the stacking direction, the positive electrode layer 22 is disposed on one surface of the current collector 26, and the negative electrode layer 24 is disposed on the other surface of the current collector 26.

[0021] A solid electrolyte layer containing a known solid electrolyte is used for the separator 20. The separator 20 forms an electrolyte layer between the positive electrode layer 22 and the negative electrode layer 24, and prevents an electrical short circuit between the positive electrode layer 22 and the negative electrode layer 24 while allowing the passage (permeation) of charge carriers such as lithium ions.

[0022] In the energy storage device 10, the current collector 26 on which the final positive electrode layer 22 in the stacking direction is arranged is the final positive electrode 28A (see FIGS. 1 and 2), and the current collector 26 on which the final negative electrode layer 24 in the stacking direction is arranged is the final negative electrode 28B (see FIG. 2, not shown in FIG. 1). In the energy storage device 10, a plurality of energy storage cells 12 are arranged in series between the final positive electrode 28A and the final negative electrode 28B.

[0023] In the electricity storage device 10, a positive electrode layer 22 and a negative electrode layer 24, each of which has a substantially rectangular shape, are applied to the center of a substantially rectangular current collector 26 when viewed in the stacking direction (plan view). The positive electrode layer 22 is a positive electrode active material layer containing a positive electrode active material, and the negative electrode layer 24 is a negative electrode active material layer containing a negative electrode active material.

[0024] The current collector 26 has an uncoated portion on the outside of the positive electrode layer 22 and the negative electrode layer 24. In the energy storage device 10, the separator 20 and the current collector 26 have the same shape and size (similar vertical and horizontal dimensions) when viewed in the stacking direction. As a result, in the energy storage cell 12, the uncoated portions of the separator 20 and the current collector 26 protrude around the entire periphery on the outside of the positive electrode layer 22 and the negative electrode layer 24 when viewed in the stacking direction.

[0025] The outer shell 18 is formed by stacking a plurality of resin frames 30 as frames, and the resin frames 30 adjacent to each other in the stacking direction are tightly joined together to form an integrated outer shell 18. Each of the resin frames 30 has a generally rectangular frame shape when viewed in the stacking direction, and the inside dimensions of the resin frames 30 are smaller than the outside dimensions of the separators 20 and the current collectors 26 and larger than the outside dimensions of the positive electrode layers 22 and the negative electrode layers 24.

[0026] As a result, the outer periphery of the separator 20 or the current collector 26 overlaps with the inner peripheral edge of the resin frame 30, and the outer periphery of the separator 20 or the current collector 26 is sandwiched and held between adjacent resin frames 30 in the stacking direction. Also, the resin frame 30 accommodates the positive electrode layer 22 or the negative electrode layer 24 inside.

[0027] Meanwhile, in the electricity storage device 10, a pressure adjusting section is provided in the resin frame 30 forming the outer shell section 18. The resin frame 30 is formed by integrally forming wall sections 32A, 32B, 32C, and 32D on four sides when viewed in the stacking direction. The walls 32A to 32D each have the same height, length, and width. The height is the dimension along the stacking direction, and the width is the dimension along the inward / outward direction of the resin frame 30. The length is the spacing dimension of the inner surface between adjacent wall sections.

[0028] Resin frame 30 is laminated such that wall portions 32A, 32B, 32C, and 32D each form a side wall of one outer shell portion 18, and wall portions 32A, 32B, 32C, and 32D each form side walls 34A, 34B, 34C, and 34D of outer shell portion 18. For this reason, the appearance of side walls 34A to 34D is made such that each of the height dimension (dimension along the stacking direction), width dimension (dimension along a direction intersecting the height direction), and thickness dimension (dimension along the inward / outward direction) is the same.

[0029] As shown in Fig. 2 and Fig. 3, the resin frame 30 has a recessed portion 36 formed as a pressure adjusting portion in a wall portion 32A forming one of the four sides. As shown in Fig. 3, the recessed portion 36 has a required width and length and is formed along the longitudinal direction of the wall portion 32A. The recessed portion 36 has a bottom and is formed with a predetermined width in the longitudinal direction of the wall portion 32A, and the recessed portion 36 has a bottom and is open toward one side in the stacking direction. As a result, the wall portion 32A is divided into an inner wall portion 38A on the inner side of the resin frame 30 and an outer wall portion 38B on the outer side of the resin frame 30 at the opening side of the recessed portion 36.

[0030] Further, the recessed portion 36 is formed in the wall portion 32A so as to be biased toward the inside (the positive electrode layer 22 or the negative electrode layer 24 side) of the resin frame 30. For this reason, in the wall portion 32A, the thickness dimension of the inner wall portion 38A is made smaller (thinner) than the thickness dimension of the outer wall portion 38B.

[0031] In the energy storage device 10, a hollow portion 40 with one recessed portion 36 is formed between two resin frames 30 (30A, 30B) in one energy storage cell 12. That is, the recessed portion 36 of the resin frame 30A in which the negative electrode layer 24 is accommodated is open toward the resin frame 30B in which the positive electrode layer 22 is accommodated, and the recessed portion 36 of the resin frame 30B is open toward the resin frame 30A.

[0032] As a result, in the energy storage device 10, the recessed portion 36 of the resin frame 30A and the recessed portion 36 of the resin frame 30B are continuous with each other to form one hollow portion 40, as shown in FIG.

[0033] In the electricity storage device 10 configured in this manner, a resin frame 30 (30B) that houses the positive electrode layer 22 and a resin frame 30 (30A) that houses the negative electrode layer 24 are stacked on the current collector 26 coated with the positive electrode layer 22 and the negative electrode layer 24 (or one of the positive electrode layer 22 and the negative electrode layer 24). In the electricity storage device 10, the current collector 26 is stacked on the resin frame 30, and the next resin frame 30 is stacked on the current collector 26.

[0034] As a result, in the energy storage device 10, an outer shell 18 is formed by the resin frame 30, and a plurality of energy storage cells 12 are stacked and arranged inside the outer shell 18. Also, in the energy storage device 10, the energy storage device 10 is charged by DC power applied between the positive electrode final electrode 28A and the negative electrode final electrode 28B, and outputs DC power of a predetermined voltage from between the positive electrode final electrode 28A and the negative electrode final electrode 28B.

[0035] Incidentally, in the electricity storage device 10, gas may be generated from the electricity storage cells 12, etc. due to various factors such as deterioration due to usage conditions (charging and discharging conditions) and deterioration over time. In the electricity storage device 10, if the internal pressure increased by the generated gas exceeds the withstand pressure of the side walls 34A-34B of the outer shell portion 18, damage will occur to the side walls 34A-34D.

[0036] Here, in the resin frame 30 forming the outer shell portion 18, a recessed portion 36 is formed in the wall portion 32A out of the wall portions 32A to 32D that form the four sides. Furthermore, between the resin frames 30A and 30B adjacent in the stacking direction, the two recessed portions 36 are connected to form a hollow portion 40. Therefore, in the outer shell portion 18, a plurality of recessed portions 36 are formed along the stacking direction in the side wall 34A formed by the wall portion 32A, and a plurality of hollow portions 40 are formed.

[0037] Furthermore, since the recessed portion 36 is formed in the wall portion 32A of the resin frame 30, the thickness dimension of the inner wall portion 38A facing the inside of the resin frame 30 is smaller than the thickness dimensions of the walls 32B to 32D.

[0038] For this reason, in the resin frame 30, the withstand pressure of the wall 32A against the internal pressure is lower than that of each of the walls 32B to 32D. Also, in the outer shell portion 18, the withstand pressure of the side wall 34A against the internal pressure is lower than that of each of the side walls 34B to 34D.

[0039] As a result, in the case of electricity storage device 10, if gas is generated within outer shell portion 18 and the internal pressure rises, damage will occur to inner wall portions 38A of each of walls 32A of resin frames 30A, 30B within side wall 34A.

[0040] In the resin frames 30A and 30B, a hollow portion 40 is formed by the recessed portion 36, and if the inner wall portion 38A is damaged, gas will flow into the hollow portion 40. Therefore, in the outer shell portion 18, a rise in internal pressure is suppressed by damage to the inner wall portion 38A.

[0041] This makes it possible to suppress changes in the spacing between adjacent current collectors 26 in the stacking direction and deformation of current collectors 26 caused by an increase in pressure in electricity storage device 10. Moreover, since hollow portion 40 is provided in side wall 34A of outer shell portion 18 in electricity storage device 10, there is no increase in volume caused by a configuration for reducing pressure.

[0042] Furthermore, in the case of the energy storage device 10, if the internal pressure of the outer shell portion 18 further increases, damage occurs in the outer wall portions 38B of the walls 32A of the resin frames 30A and 30B within the side wall 34A, causing damage to the side wall 34A. However, in the case of the energy storage device 10, even if the internal pressure of the outer shell portion 18 increases, damage does not occur in the side walls 34B to 34D other than the side wall 34A, and the damage to the outer shell portion 18 does not affect the surroundings of the side walls 34B to 34D.

[0043] Therefore, in the electricity storage device 10, damage caused by an increase in internal pressure is controlled so that the side wall 34A of the outer shell portion 18 is damaged. Moreover, in the resin frames 30A, 30B, the pressure resistance of the wall portion 32A can be adjusted by the recessed portion 36 formed in the wall portion 32A. That is, the pressure resistance can be adjusted to be lower by reducing the thickness dimension of the inner wall portion 38A formed in the wall portion 32A by the recessed portion 36, increasing the height dimension along the stacking direction, increasing the length dimension, or the like.

[0044] In this embodiment, the separator 20 is a solid electrolyte layer. However, the disclosed power storage device may use an electrolyte layer using a liquid electrolyte. In this case, for example, a porous film, woven fabric, or nonwoven fabric made of a required resin may be used for the separator 20, and an electrolyte solution may be injected into the outer shell 18, thereby impregnating the separator 20, the positive electrode layer 22, and the negative electrode layer 24 with the electrolyte solution. [Explanation of symbols]

[0045] 10. Energy storage device 12 Battery Cells 18 Outer shell 20 Separator (electrolyte layer) 22 Positive electrode layer (electrode layer) 24 Negative electrode layer (electrode layer) 26 Current collector 30 (30A, 30B) Resin frame (frame body) 32A Wall section 34A side wall 36 Concave portion (pressure resistance adjustment portion) 38A Inner wall 40 Hollow part

Claims

[Claim 1] a laminate in which, when a plurality of such electrodes are stacked in one direction, electrode layers having polarities different from each other are provided on one surface and the other surface of an electrolyte layer, and a current collector is disposed on a surface of each of the electrode layers opposite to the electrolyte layer; a frame body provided for each of the electrode layers, the electrode layer being housed inside a rectangular frame, and stacked in the one direction to form an outer shell portion; a pressure adjusting section formed on one side of the frame body for lowering a withstand pressure of an inner wall of the one side against a pressure from inside the frame body to a lower withstand pressure of the inner walls of the other three sides; A power storage device comprising:

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