Power storage device

Abstract

To provide a power storage device into which an electrolytic solution can be efficiently injected.SOLUTION: In a resin frame 30 of a power storage device 10, a separator is arranged at one side and a current collector 26 is arranged at the other side, in a laminating direction, where a negative electrode layer 24 arranged in the current collector 26 is stored and a space part 32 is formed between the resin frame 30 and the negative electrode layer 24. A spacer 34 is arranged in the space part 32. A base part 40 of the spacer 34 contacts the separator and the current collector 26, and a passage part 48 extending along an outer periphery of the negative electrode layer 24 is formed between the base part 40 and the negative electrode layer 24. This can prevent the passage part 48 from being narrowed when the inside of the space part 32 is decompressed, so that an electrolytic solution can be injected into the passage part 48 efficiently, in the power storage device.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 cell 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 such an electricity storage device, the bipolar electrode is disposed in a resin case (see, for example, Patent Document 1). In addition, in the electricity storage device, when each cell of the bipolar electrode is disposed in the case, spacers made of rubber-based resin are disposed at predetermined intervals along the periphery of the current collector in each cell to maintain the spacing between the current collectors, so that the current collectors are held in the case (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4370902 [Patent Document 2] JP 2018-049792 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, there is an electrolyte type of electricity storage device in which an electrolyte is injected into the inside of a cell. In an electrolyte type electricity storage device, if air gets into the internal space of the cell, it becomes difficult to inject the electrolyte, and there is a problem that it takes a long time to inject the electrolyte. As a method for preventing this, it is considered to inject the electrolyte after reducing the pressure in the internal space of the cell.

[0006] However, in an energy storage device, if the internal space of a cell is narrowed (reduced) by reducing the pressure therein, there is a concern that problems may arise such as the electrolyte becoming less likely to flow when injected, and there is room for improvement in terms of effective injection of the electrolyte.

[0007] An object of the present disclosure is to provide an electricity storage device in which an electrolyte solution can be efficiently injected. [Means for solving the problem]

[0008] One aspect of the electricity storage device of the present disclosure includes: an electricity storage unit in which a plurality of electrode bodies are stacked, each of which is provided with an electrode layer, one surface of a current collector being a positive electrode and the other surface being a negative electrode, and a separator, on which an electrolyte membrane is formed by an electrolyte solution, is arranged on a surface of each of the electrode layers opposite the current collector; and a resin frame body in which the separator is arranged on one side of the stacking direction of the electrode bodies and the current collector is arranged on the other side, and in which the electrode layer provided on the current collector is housed, and in which a space portion in which the electrolyte solution is sealed is formed on the outer periphery of the electrode layer, and in which a plurality of the frames are stacked in the stacking direction, an outer shell portion in which each of the current collector and the separator of the electricity storage unit is held; and a spacer that is arranged in the space portion between the electrode layer of at least one of the positive electrode and negative electrode and the frame body, so that the separator and the current collector sandwiching the frame body are held at a predetermined distance, and in which a flow path portion for the electrolyte solution is formed that is continuous around the entire outer periphery of the electrode layer within the space portion of the frame body.

[0009] In the power storage device of this embodiment, a plurality of electrode bodies are stacked in the electrode section. In the electrode body, an electrode layer is provided on a current collector, and one surface of the current collector of the electrode layer is a positive electrode and the other surface is a negative electrode. In addition, a separator is disposed on the surface of each electrode layer opposite the current collector, and the separator forms an electrolyte membrane between the positive electrode layer and the negative electrode layer by an electrolytic solution.

[0010] The outer shell portion is formed by stacking a plurality of frames, each made of resin, in the stacking direction of the electrode body. The frame has a separator arranged on one side in the stacking direction and a current collector arranged on the other side, and houses the electrode layer provided on the current collector, and a space portion in which an electrolyte is sealed is formed on the outer periphery of the electrode layer. The outer periphery of each of the current collector and separator of the electrode unit is held between the stacked frame bodies by stacking the frame bodies.

[0011] In addition, a spacer is disposed in the outer shell in a space of the frame in which at least one of the positive and negative electrode layers is housed. The spacer maintains a predetermined distance between the separator and the current collector that sandwich the frame, and forms a flow path for the electrolyte that is continuous around the entire outer periphery of the electrode layers in the space of the frame.

[0012] This ensures that even if the space between the frame and the electrode layer in the outer shell is reduced in pressure, the electrolyte flow path formed by the spacer is secured, allowing the electrolyte to be effectively injected around the entire circumference of the electrode layer. Effect of the Invention

[0013] According to the present disclosure, even if the space between the frame and the electrode layer in the outer shell is depressurized, the flow path can be prevented from being narrowed by the depressurization of the space, and therefore the electrolyte can be effectively injected around the entire circumference of the electrode layer. As a result, the electricity storage device of the present disclosure has an effect of preventing a shortage of electrolyte around the electrode layer. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view showing a schematic external appearance of a power storage device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a perspective view showing an example of a main part of a power storage device. [Diagram 3] 2 is a schematic cross-sectional view showing a main part of the electricity storage device. FIG. [Figure 4] 5A to 5C are schematic diagrams illustrating an example of a flow of assembling the power storage device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the power storage device of the present disclosure will be described in detail with reference to the drawings. Fig. 1 shows a perspective view of a main part of an energy storage device 10 according to this embodiment, Fig. 2 shows a perspective view of the appearance of the energy storage device 10, and Fig. 3 shows a side cross-sectional view of the main part of the energy storage device 10. Fig. 3 shows an example of a cross-section cut along the stacking direction.

[0016] 3, the energy storage device 10 according to this embodiment includes energy storage cells 12 as electrode bodies, and the energy storage device 10 has a plurality of energy storage cells 12 stacked in one direction to form an energy storage section. In the drawing, the stacking direction of the energy storage cells 12 is indicated by the direction of arrow A.

[0017] 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). The power storage device 10 is of a liquid electrolyte type that uses an electrolytic solution as the electrolyte. For example, a lithium ion secondary battery or a nickel-metal hydride secondary battery can be used for this power storage device 10.

[0018] In the energy storage device 10, the energy storage cell 12 comprises an electrode stack 16 and an outer shell portion 18 that surrounds the outer periphery of the electrode stack 16 and serves as a housing to house the electrode stack 16, and each of the electrode stack 16 and the outer shell portion 18 has an overall outline shape that is approximately rectangular.

[0019] The electrode laminate 16 includes a separator 20, a positive electrode layer 22 as a positive electrode layer, and a negative electrode layer 24 as a negative electrode layer. In the electrode laminate 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 laminate 16 includes the positive electrode layer 22, the separator 20, and the negative electrode layer 24 stacked in this order.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] A porous film, woven fabric, or nonwoven fabric made of a required resin is used for the separator 20. The separator 20 is impregnated with an electrolytic solution to form 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.

[0024] 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 3), 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. 3, 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.

[0025] In the energy storage device 10, the positive electrode layer 22 and the negative electrode layer 24, each of which is substantially rectangular, are provided in the center of the current collector 26, which is substantially rectangular when viewed in the stacking direction (plan view), and the current collector 26 has uncoated portions on the outer sides of the positive electrode layer 22 and the negative electrode layer 24. In addition, 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 outer sides of the positive electrode layer 22 and the negative electrode layer 24 when viewed in the stacking direction.

[0026] The outer shell portion 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 body in the outer shell portion 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. The inside dimensions of the resin frames 30 are also larger than the outside dimensions of the positive electrode layers 22 and the negative electrode layers 24.

[0027] As a result, the outer periphery of the separator 20 or the current collector 26 overlaps with the inner peripheral portion 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. The resin frame 30 accommodates the positive electrode layer 22 or the negative electrode layer 24 inside, and each of the resin frames 30 forms a space 32 with a required opening width and volume between the inner wall and the end face of the accommodated positive electrode layer 22 or negative electrode layer 24. In the resin frame 30, the space 32 is continuous with the outer periphery of the positive electrode layer 22 or negative electrode layer 24 all around.

[0028] The space 32 is sealed by the separator 20 and the current collector 26 between the resin frame 30 and the positive electrode layer 22 or the negative electrode layer 24. At this time, the uncoated portion of the current collector 26 faces the space 32.

[0029] In the electricity storage device 10, a known electrolyte solution (not shown) is sealed in the space 32 formed in the outer shell 18. In the electricity storage device 10, the electrolyte solution sealed in the space 32 is impregnated into each of the separator 20, the positive electrode layer 22, and the negative electrode layer 24. The electrolyte solution contains, for example, a non-aqueous solvent and a supporting salt. Examples of the non-aqueous solvent include organic solvents such as carbonates, ethers, esters, nitriles, sulfones, and lactones. Examples of the supporting salt include lithium salts such as LiPF6.

[0030] On the other hand, in the energy storage device 10, a spacer 34 is disposed as a retaining member in at least a part of the space 32 in the outer shell 18. In the energy storage device 10, the spacer 34 is disposed in at least one of the space 32 between the positive electrode layer 22 and the resin frame 30 (the resin frame 30 in which the positive electrode layer 22 is accommodated) and between the negative electrode layer 24 and the resin frame 30 (the resin frame 30 in which the negative electrode layer 24 is accommodated). The spacer 34 may also be disposed in each of the space 32 between the positive electrode layer 22 and the resin frame 30 and between the negative electrode layer 24 and the resin frame 30. In the energy storage device 10, as an example, the spacer 34 is disposed in the space 32 between the negative electrode layer 24 and the resin frame 30.

[0031] The spacer 34 is made of a resin that is resistant to the electrolyte and does not easily elastically deform when pressure is applied, and the spacer 34 is made of the same resin as the outer shell portion 18 (resin frame 30).

[0032] 2 and 3, the spacer 34 includes a substantially rectangular frame-shaped base 40, a plurality of branch portions 42 as flow path forming portions, and a pair of extension portions 44. Each of the plurality of branch portions 42 protrudes from the base 40 toward the inside of the frame formed by the base 40. The extension portions 44 extend in pairs from the base 40 toward the outside of the frame formed by the base 40.

[0033] Furthermore, resin frame 30 in which spacer 34 is arranged has an opening 46 formed in the center of one side (see FIG. 2), and resin frame 30 communicates with the outside and spaces 32 via opening 46. In electricity storage device 10, openings 46 are used to inject electrolyte into each space 32 in outer shell 18 (resin frame 30), and after the electrolyte is injected, openings 46 are closed to hermetically seal the inside of outer shell 18.

[0034] The base 40 of the spacer 34 is in the form of a substantially rectangular frame when viewed in the stacking direction, and has a substantially rectangular cross section cut along a direction intersecting the insertion direction, and the outer shape of the base 40 is similar to the inner shape of the resin frame 30. As a result, by disposing (fitting) the spacer 34 in the space 32 of the resin frame 30, the outer surface of the base 40 comes into contact with the inner surface of the resin frame 30, and a flow path 48 is formed between the inner surface of the base 40 and the end face of the negative electrode layer 24 as a gap of a predetermined width through which the electrolyte can pass.

[0035] The height dimension of the base 40 (the dimension along the stacking direction) is the same as the distance between the separator 20 and the current collector 26 in the resin frame 30. This allows the base 40 to have a height dimension that contacts each of the separator 20 and the current collector 26 in the resin frame 30.

[0036] The base 40 has a center portion of one side cut out by a predetermined width, and a pair of extension portions 44 extend outward (outside the frame) from each cutout portion. The cutout portions of the base 40 are positioned to face an opening 46 of the resin frame 30. As a result, in the spacer 34, the pair of extension portions 44 are disposed within the opening 46 of the resin frame 30, and a flow path portion 48 on the inside of the base 40 communicates with the outside of the resin frame 30 from between the pair of extension portions 44.

[0037] The spacer 34 has a plurality of branches 42 provided at predetermined intervals on each of the four sides of the base 40, and each of the branches 42 extends from the base 40 toward the negative electrode layer 24 so as to be able to come into contact with an end surface of the negative electrode layer 24. The height dimension of each of the branches 42 is smaller than the height dimension of the base 40.

[0038] As a result, when the spacer 34 is placed in the resin frame 30, the branches 42 come into contact with the end faces of the negative electrode layer 24, so that the negative electrode layer 24 is held in the resin frame 30 via the spacer 34 (movement in a direction intersecting the stacking direction is restricted). In addition, the flow path 48 is surrounded by the base 40, the negative electrode layer 24, the separator 20, and the current collector 26, and is continuous around the entire circumference of the negative electrode layer 24.

[0039] Next, the operation of this embodiment will be described. Fig. 4 shows an example of a flow of assembling the electricity storage device 10. In Fig. 4, (A), (B), (C), and (D) respectively indicate a first step, a second step, a third step, and a fourth step, which are performed in order at a predetermined timing starting from the first step.

[0040] In the first step, the current collector 26 having the negative electrode layer 24 applied to the center portion is placed on one side in the stacking direction of the resin frame 30. As a result, the negative electrode layer 24 is accommodated in the resin frame 30, and a space 32 is formed between the resin frame 30 and the negative electrode layer 24 corresponding to the uncoated portion of the current collector 26.

[0041] In the second step, the spacer 34 is disposed in the space 32 in the resin frame 30. As a result, the base 40 is disposed between the resin frame 30 and the negative electrode layer 24 in the resin frame 30, and the negative electrode layer 24 is held by the resin frame 30 via the base 40 and the branch portions 42. In addition, a pair of extension portions 44 of the spacer 34 are disposed in the opening portion 46 of the resin frame 30. Furthermore, a flow path portion 48 is formed between the base 40 of the spacer 34 and the negative electrode layer 24.

[0042] In the third step, the separator 20 is placed in the resin frame 30 in which the spacers 34 are placed, and the next layer of resin frames 30 is laminated. After this, the current collector 26 coated with the positive electrode layer 22 and the negative electrode layer 24 is placed on the laminated resin frames 30 (not shown). As a result, the outer shell 18 is formed by laminating and integrating a plurality of resin frames 30 (not shown).

[0043] Thereafter, the electrolyte is injected through the openings 46 into each of the spaces 32 in the outer shell 18. In a fourth step, the openings 46 used for injecting the electrolyte are closed. This results in an electricity storage device 10 in which the electrolyte is sealed within the outer shell 18, and in the electricity storage device 10, the separator 20, the positive electrode layer 22, and the negative electrode layer 24 are impregnated with the electrolyte.

[0044] Here, in the electricity storage device 10, prior to injecting the electrolyte into the space 32 of each resin frame 30 in the outer shell 18, the space 32 is depressurized, and the electrolyte is injected into the depressurized space 32. The resin frame 30 is provided with an opening 46 communicating with the space 32, and a pair of extension parts 44 of the spacer 34 are disposed in the opening 46. The space between the pair of extension parts 44 is communicated with a flow path part 48 formed in the space 32 by the spacer 34. Therefore, in the electricity storage device 10, the opening 46 can be used to depressurize the space 32 and inject the electrolyte.

[0045] In the electricity storage device 10, the pressure inside each of the spaces 32 is reduced prior to the injection of the electrolyte solution into each of the resin frames 30, thereby facilitating the injection of the electrolyte solution.

[0046] A spacer 34 is disposed in the resin frame 30 that forms the outer shell 18, and the spacer 34 forms a flow path 48 that is continuous around the entire circumference of the negative electrode layer 24 in the space 32 by means of a base 40, and the base 40 abuts against the separator 20 and the current collector 26. Therefore, even if the pressure inside the space 32 of the resin frame 30 is reduced, the base 40 maintains the distance between the separator 20 and the current collector 26. As a result, even if the space 32 is depressurized within the resin frame 30, narrowing of the flow path 48 between the base 40 of the spacer 34 and the negative electrode layer 24 can be suppressed. Moreover, since the negative electrode layer 24 is held in the resin frame 30 via the spacer 34, the negative electrode layer 24 can be held in a stable state during depressurization or injection of the electrolyte, and the spacer 34 itself does not shift.

[0047] Furthermore, in the resin frame 30, the electrolyte can be injected from between a pair of extension parts 44 arranged in the opening 46. The pair of extension parts 44 extend from the base 40, and the space between the pair of extension parts 44 is continuous with a flow path part 48 formed between the base 40 and the negative electrode layer 24. This allows the electrolyte to be smoothly injected into the flow path part 48 in the electricity storage device 10.

[0048] Furthermore, in the energy storage device 10, when the space 32 of the resin frame 30 is depressurized, the spacer 34 prevents the flow path 48 formed within the space 32 from narrowing, making it possible to efficiently inject the electrolyte into the flow path 48 of the resin frame 30.

[0049] Furthermore, in the resin frame 30, the space 32 on the negative electrode layer 24 side and the space 32 on the positive electrode layer 22 side are adjacent to each other via the separator 20. This allows the electrolyte to be injected from the space 32 on the negative electrode layer 24 side to the space 32 on the positive electrode layer 22 side within the outer shell 18 in the electricity storage device 10, thereby preventing insufficient injection of the electrolyte.

[0050] Therefore, in the electricity storage device 10, the separator 20, the positive electrode layer 22, and the negative electrode layer 24 can each be impregnated with the electrolyte, and the electricity storage device 10 is capable of stable charge and discharge operations.

[0051] In this embodiment, a spacer 34 is used that has a base 40, a plurality of branches 42, and a pair of extensions 44. However, the base 40 may be spaced apart from the inner surface of the resin frame 30, and the spacer may have any shape that can form a flow path that is continuous around the entire circumference of the electrode layer while maintaining the distance between the separator and the current collector by being placed in the space of the frame. [Explanation of symbols]

[0052] 10. Energy storage device 12 Storage cell (electrode body) 14 Bipolar Electrode 18 Outer shell 20 Separator 22 Positive electrode layer (electrode layer) 24 Negative electrode layer (electrode layer) 26 Current collector 30 Resin frame (frame) 32 Space section 34 Spacer 40 base 42 Branch 48 Flow passage

Claims

[Claim 1] an electricity storage section in which a plurality of electrode bodies are stacked, each electrode layer having a positive electrode on one side of a current collector and a negative electrode on the other side, and a separator on which an electrolyte membrane is formed by an electrolyte solution is disposed on the side of each of the electrode layers opposite to the current collector; the separator is disposed on one side of the electrode body in a stacking direction, the current collector is disposed on the other side, the electrode layer provided on the current collector is housed therein, and a space portion into which the electrolytic solution is sealed is formed on the outer periphery of the electrode layer, and an outer shell portion is provided to hold the outer periphery of each of the current collector and the separator of the power storage unit by stacking a plurality of the frame bodies in the stacking direction; a spacer that is disposed in the space between the electrode layer of at least one of the positive electrode and the negative electrode and the frame, thereby maintaining a predetermined distance between the separator and the current collector that sandwich the frame, and forming a flow path for the electrolyte that is continuous around the entire outer periphery of the electrode layer within the space of the frame; A power storage device comprising:

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