Power storage module

Abstract

The utility model provides an electric power storage module which can restrain thickness increase caused by an overlapping portion of an electrode coating portion of a current collector and a reinforcing component, thereby restrain reduction of energy density of the electric power storage module. A power storage module in which a plurality of power storage cells are stacked, each power storage cell being provided with: a spacer that seals the space between the edges of facing current collectors and forms a housing space for housing an electrolyte solution; and a reinforcing member that reinforces the uncoated portions of the current collectors, which are not coated with an active material layer. The reinforcing members have a portion disposed along the uncoated portion so as to straddle the peripheral edge portion of the active material layer and the spacer, and the reinforcing members adjacent to each other in the lamination direction have non-overlapping portions that do not overlap at the peripheral edge portion of the active material layer.

Description

Technical Field

[0001] This disclosure relates to an energy storage module. Background Technology

[0002] Japanese Patent Application Publication No. 2022-069042 discloses an energy storage unit having a positive electrode, a negative electrode, a separator, a spacer, and a reinforcing member. The positive and negative electrodes each have an active material layer on one side of a current collector made of metal foil. The positive and negative electrodes are arranged such that the active material layers face each other. The separator is disposed between the positive and negative electrodes, between the active material layers. The spacer is disposed between the positive and negative electrodes, sealing the edges of the current collector by surrounding the active material layers to form a storage space for containing electrolyte. The reinforcing member reinforces the uncoated portions of the current collector that do not have an active material layer. When viewed from the opposite direction of the active material layers in the positive and negative electrodes, the current collector has an uncoated portion between the spacer and the active material layer. The reinforcing member is disposed along the uncoated portion, spanning the boundary between the active material layer and the uncoated portion, and the boundary between the spacer and the uncoated portion, when viewed from the opposite direction.

[0003] To prevent the current collector foil from cracking or bending due to decompression or thermal shock, reinforcing components are sometimes arranged across the electrode periphery and electrode coating area to improve the overall strength of the electrode body. Figure 5 This illustrates an example where, when a portion of the spacer is configured as a reinforcing member spanning the electrode periphery and the electrode coating area, the thickness increases due to the overlap of the reinforcing members. For example... Figure 5 As shown, the thickness of the overlapping portion 40, where the electrode coating portion (negative electrode 14) of the current collector 10 overlaps with the reinforcing member 22B (part of the spacer 20), increases. Moreover, in an energy storage module (hereinafter sometimes simply referred to as a "module") with multiple such electrode bodies stacked, the increase in the thickness of the overlapping portion 40 becomes significant, and the energy density of the module may decrease. Utility Model Content

[0004] The objective of this disclosure is to provide an energy storage module that can suppress the increase in thickness caused by the overlap between the electrode coating portion of the current collector and the reinforcing member, thereby suppressing the decrease in energy density of the energy storage module.

[0005] The means used to solve the above problems include the following methods.

[0006] The first type of energy storage module comprises multiple stacked energy storage units, each energy storage unit including: a positive electrode and a negative electrode, wherein active material layers coated on the central regions of opposite sides of each current collector are disposed opposite to each other; a separator between the active material layers of the positive electrode and the negative electrode; a spacer disposed to surround the active material layers, sealing the edges of the opposite current collectors to form a receiving space containing electrolyte; and a reinforcing member that reinforces the uncoated portions of the current collectors where the active material layers are not coated, wherein, when viewed from the opposite direction of the active material layers, the current collectors have the uncoated portions between the spacer and the active material layers, and when viewed from the opposite direction, the reinforcing member is discontinuously disposed along the uncoated portions across the periphery of the active material layers and the spacer, and when viewed from the opposite direction, adjacent reinforcing members in the opposite direction have non-overlapping portions that do not overlap with the periphery of the active material layers.

[0007] The second type of energy storage module is the same as the first type, but when viewed from the opposite direction, the reinforcing member has a concave-convex portion at the periphery of the active material layer, and adjacent reinforcing members in the opposite direction have non-overlapping portions at the periphery of the active material layer where the concave-convex portions do not overlap.

[0008] The energy storage module of the third type is in the first or second type, wherein the non-overlapping portions of the reinforcing member are not adjacent in the opposite direction.

[0009] The energy storage module of the fourth type is formed as an integral, identical component in any of the first to third types, where the spacer and the reinforcing member are integrated.

[0010] According to the energy storage module disclosed herein, the increase in thickness caused by the overlap between the electrode coating portion of the current collector and the reinforcing member can be suppressed, thereby suppressing the decrease in energy density of the energy storage module. Attached Figure Description

[0011] Figure 1 This is a perspective view showing an example of the appearance of the energy storage module involved in this disclosure.

[0012] Figure 2 This is a schematic diagram illustrating an example of an energy storage module constructed by alternately stacking energy storage units with comb-shaped spacers.

[0013] Figure 3A It means Figure 2 A schematic diagram of the cross section of line A-A' in the diagram.

[0014] Figure 3B It means Figure 2A schematic diagram of the cross section of line B-B' in the diagram.

[0015] Figures 4A to 4D This is a schematic diagram showing a structure in which reinforcing members (part of the spacer) are arranged in alternating layers in a non-overlapping manner.

[0016] Figure 5 This is a schematic diagram illustrating an example of the increase in thickness caused by the overlap of the reinforcing member (part of the spacer). Detailed Implementation

[0017] The energy storage module involved in this disclosure will be described below with reference to the accompanying drawings. In the drawings, the same or equivalent parts are labeled with the same reference numerals, and reference numerals and descriptions are appropriately omitted in the same drawings.

[0018] The energy storage module disclosed herein has a configuration in which the reinforcing member is stacked in a manner in which the overlapping portion of the electrode coating portion (active material layer) and the reinforcing member overlaps discontinuously in the stacking direction of multiple energy storage cells. This mitigates the increase in thickness during the stacking of energy storage cells and suppresses the decrease in energy density of the module.

[0019] Figure 1 A perspective view illustrating an example of the appearance of the energy storage module involved in this disclosure. For example... Figure 1 As shown, the energy storage module 100 disclosed herein is a cuboid. The energy storage module 100 includes: an electrode stack 102 comprising stacked bipolar electrode groups, a resin body 104 surrounding and holding the sides of the electrode stack 102, and an electrolyte (not shown). The energy storage module 100 disclosed herein has a configuration comprising multiple stacked energy storage units. The length and width of the energy storage module 100 are not particularly limited and may each exceed 1 m.

[0020] The energy storage unit includes a positive and a negative electrode formed on each side of an opposing current collector, a separator, a spacer, and a reinforcing member. The reinforcing member reinforces the uncoated portions of the current collector where no active material layer of the positive or negative electrode is coated. The reinforcing member may be a component different from the spacer, or it may be the same component integrated with the spacer, i.e., the spacer and the reinforcing member are integrally formed. Hereinafter, as an example of the energy storage module according to this disclosure, an embodiment in which the spacer and the reinforcing member are integrally formed will be described.

[0021] Figure 2 This refers to the energy storage module 100, which is formed by alternately stacking energy storage units 110 and 120. Figure 3A It means Figure 2 A cross-sectional diagram of the section of line A-A' in the diagram. Figure 3B To indicate Figure 2A schematic diagram of the cross-section of line B-B' in the diagram. Additionally, in... Figure 2 For ease of explanation, the diagrams of the positive electrode 12, the separator 16, and the sealing part 18 are omitted.

[0022] The energy storage unit 110 includes a positive electrode 12 and a negative electrode 14 formed on one side of the opposing current collector 10, a separator 16, a spacer 20A, and a reinforcing member 22A. The energy storage unit 120 includes a positive electrode 12 and a negative electrode 14 formed on each side of the opposing current collector 10, a separator 16, a spacer 20B, and a reinforcing member 22B.

[0023] The positive electrode 12 and the negative electrode 14 are formed by placing active material layers coated on the central regions of each side of the opposing current collector 10 opposite each other.

[0024] The separator 16 is located between the active material layers 12 and 14 of the positive electrode 12 and the negative electrode 14 (between the positive electrode 12 and the negative electrode 14).

[0025] Spacers 20A and 20B are arranged to surround the active material layers 12 and 14, sealing the edges of the opposing current collectors 10 to form a containment space T for containing the electrolyte.

[0026] When viewed from the relative directions of the active material layers 12 and 14 (which are the same as the stacking directions of each energy storage unit 110 and 120), there are uncoated portions between the current collector 10 and the spacers 20A and 20B and the active material layers 12 and 14.

[0027] The reinforcing members 22A and 22B reinforce the uncoated portions of the uncoated active material layers 12 and 14 in the current collector 10. When viewed from the opposite direction of the active material layers 12 and 14, the reinforcing members 22A and 22B have portions arranged along the uncoated portions in a manner that spans the periphery of the active material layers 12 and 14 and the spacers 20A and 20B.

[0028] In this embodiment, the spacer 20A and the reinforcing member 22A are formed as an integral part of the same component, and the spacer 20B and the reinforcing member 22B are formed as an integral part of the same component.

[0029] like Figure 2 As shown, the spacers 20A and 20B in each energy storage cell 110 and 120 have an uneven shape (sometimes referred to as "comb shape") when viewed from the opposite direction (the same as the stacking direction). In such comb-shaped spacers 20A and 20B, the concave portions function as spacers 20A and 20B for forming the electrolyte containment space T, and the convex portions function as reinforcing members 22A and 22B for reinforcing the uncoated portions of the uncoated active material layer 14.

[0030] In this embodiment, comb-shaped spacers 20A and 20B are disposed in the space on the positive electrode 12 side, and the ends of reinforcing members 22A and 22B overlap with the peripheral portion on the negative electrode 14 side. By alternately stacking the energy storage units 110 and 120 in this way, the overlap between the reinforcing members (comb portion) 22 and the negative electrode 14 does not accumulate in the stacking direction, and the bulge inside the module is gently reduced, thus mitigating the unevenness of the module. The total thickness of the module does not increase, and the reduction in energy density is suppressed. In addition, since the space is necessary for generating gas through charging and discharging, forming the spacers 20A and 20B in a comb shape also has the advantage of ensuring a wider space (accommodation space) Y.

[0031] Each energy storage unit 110, 120 is configured such that, when alternately overlapped, the position of the protrusion of the spacer in one energy storage unit becomes the position of the concave portion of the spacer in the other energy storage unit. Therefore, by alternately overlapping the energy storage units 110, 120 to form an energy storage module, the protrusions of the spacers in adjacent energy storage units 110, 120, which function as reinforcing members, do not overlap continuously in the stacking direction. When the energy storage units 110, 120 are alternately stacked, the reinforcing members 22A, 22B adjacent in the opposite direction (stacking direction) become non-overlapping portions where the protrusions and concave portions do not overlap at the periphery of the active material layers 12, 14. Therefore, when the energy storage units are stacked, the increase in thickness caused by overlapping reinforcing members in the stacking direction is alleviated, and the decrease in the energy density of the module is reduced.

[0032] Furthermore, although the recesses of each reinforcing member 22A and 22B are non-overlapping, when the energy storage units 110 and 120 are overlapped, even if the recesses of each reinforcing member 22A and 22B are adjacent in the opposite direction, it is impossible to obtain the effect of suppressing the accumulation of overlap between the reinforcing member 22 and the negative electrode 14. Therefore, it is preferable that the non-overlapping portions (recesses) of the reinforcing members 22A and 22B are not adjacent in the opposite direction.

[0033] The manufacturing method of the energy storage module 100 disclosed herein is not particularly limited. The energy storage module disclosed herein can be manufactured by sequentially stacking electrode bodies and spacers. An example of the manufacturing method of the energy storage module disclosed herein will be described below. Figures 4A to 4D An example of a method for manufacturing the energy storage module involved in this disclosure is shown.

[0034] First, such as Figure 4A As shown, the electrode body with the sealing portion 18 is fused to the outer periphery of the current collector 10. Next, as... Figure 4B As shown, a separator 16 is stacked on the negative electrode 14. Next, as... Figure 4CAs shown, the spacers 20 are stacked in a comb-tooth shape. The comb-tooth-shaped spacers 20 are arranged alternately in the layers with the comb-tooth portions (reinforcing members) of adjacent units in the stacking direction not overlapping. Next, as... Figure 4D As shown, an electrode body with a sealing part 18 is stacked on the outer periphery and fused together.

[0035] By repeatedly stacking in this order, an energy storage module can be obtained by overlapping multiple energy storage units, in which the accumulation of overlap between the reinforcing component 22 and the negative electrode 14 is suppressed.

[0036] The following describes in detail the constituent materials of the energy storage module involved in this disclosure, but the constituent materials of the energy storage module involved in this disclosure are not limited to the following description.

[0037] The electrode stack 102 is a cuboid. The electrode stack 102 comprises multiple bipolar electrodes stacked in layers separated by partitions 16. For example... Figure 3A and Figure 3B As shown, the electrode stack 102 has multiple bipolar electrodes, multiple separators 16, a positive-side terminal electrode (not shown), and a negative-side terminal electrode (not shown). The multiple bipolar electrodes and multiple separators 16 are stacked alternately along the axial direction. The positive-side terminal electrode is stacked across the separator 16 on the bipolar electrode located in the stacking direction among the multiple bipolar electrodes. The negative-side terminal electrode is stacked across the separator 16 on the bipolar electrode located in the opposite stacking direction among the multiple bipolar electrodes.

[0038] The bipolar electrode includes a current collector 10, a positive electrode 12, and a negative electrode 14. The periphery of the current collector 10 is fused to the resin body 104 (sealing portion 18). The positive electrode 12 is formed on one side of the current collector 10. The negative electrode 14 is formed on the other side of the current collector 10. The bipolar electrode can have a known configuration.

[0039] During the discharge or charging of the energy storage module 100, the current collector 10 supplies current to the positive electrode 12 and the negative electrode 14. Examples of materials that can be used as the current collector 10 include aluminum foil, copper foil, nickel foil, titanium foil, and stainless steel foil. A coating layer can be formed on the surface of the current collector 10 using known methods (e.g., plating, spraying, etc.). The thickness of the current collector 10 can range from 1 μm to 100 μm.

[0040] The positive electrode 12 contains a positive electrode active material capable of absorbing and releasing charge carriers (e.g., lithium composite metal oxides with a layered rock salt structure, metal oxides with a spinel structure, polyanionic compounds, etc.). Depending on the requirements, the positive electrode 12 may also contain conductive additives (e.g., carbon nanofibers), binders (e.g., polyvinylidene fluoride), electrolyte supporting salts (lithium salts) for improving ionic conductivity, polymeric electrolytes, and additives (e.g., trifluoropropylene carbonate, fillers as reinforcing materials, etc.). The thickness of the positive electrode 12 can range from 2 μm to 500 μm.

[0041] The negative electrode 14 contains a negative electrode active material capable of absorbing and releasing charge carriers (e.g., carbon (e.g., natural graphite, artificial graphite), compounds capable of alloying with lithium (e.g., silicon, tin, etc.)). The negative electrode 14 may also, as needed, contain conductive additives for improving electronic conductivity (e.g., acetylene black), binders (e.g., polyvinylidene fluoride), electrolyte support salts (lithium salts) for improving ionic conductivity, polymeric electrolytes, and additives (e.g., trifluoropropylene carbonate, fillers as reinforcing materials, etc.). The thickness of the negative electrode 14 can be from 2 μm to 500 μm. The thickness of the negative electrode 14 can be the same as or different from the thickness of the positive electrode 12. In this embodiment, as... Figure 3A and Figure 3B As shown, the length of the negative electrode 14 is longer than the length of the positive electrode 12.

[0042] The separator 16 maintains the distance between the positive electrode 12 and the negative electrode 14 to prevent short circuits and allows charge carriers such as lithium ions to pass through. The periphery of the separator 16 is fused to the resin body 104 (sealing part 18). The separator 16 is held by the resin body 104. Examples of materials that can be used for the separator 16 include porous resin sheets or nonwoven fabrics. Examples of materials that can be used for porous resin sheets include polyolefins (polypropylene, polyethylene, etc.). Examples of materials that can be used for nonwoven fabrics include polypropylene, polyethylene terephthalate, methylcellulose, etc. The separator 16 can have a known configuration.

[0043] The resin body 104 forms a receiving space T between adjacent bipolar electrodes in the stacking direction. The positive electrode 12, negative electrode 14, and separator 16 are housed in the receiving space T in a state containing electrolyte. In this embodiment, the resin body 104 prevents the electrolyte contained in the receiving space T from leaking to the outside. The resin body 104 also prevents moisture from entering the receiving space T from the outside of the energy storage module 100. Furthermore, the resin body 104 prevents internal gases generated from the positive electrode 12 or negative electrode 14 during charging and discharging from leaking to the outside of the energy storage module 100.

[0044] The resin body 104 is a rectangular cylindrical object with a rectangular cross-section. In addition to the sealing portion 18 that holds the periphery of the current collector 10 and the partition 16, the resin body 104 also includes a spacer 20 and a reinforcing member 22.

[0045] Sealing portions 18 are arranged along the stacking direction between the current collector 10 and the partition 16. Each sealing portion 18 is a rectangular cylindrical object. The sealing portions 18 are fused to the periphery of the current collector 10. Adjacent sealing portions 18 are fused to each other in the stacking direction. Therefore, the periphery of the current collector 10 and the periphery of the partition 16 are respectively held within the resin body 104.

[0046] Materials used for the resin body 104 (sealing part 18, spacer 20, reinforcing part 22) include, for example, polyethylene, polystyrene, acrylonitrile-butadiene-styrene copolymer resin (ABS resin, modified polypropylene, acrylonitrile-styrene resin), etc.

[0047] The electrolyte is contained in the containment space T. The electrolyte may also contain a non-aqueous solvent and a lithium salt. Examples of lithium salts include LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2. Examples of non-aqueous solvents include cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers. Non-aqueous electrolytes may also contain additives (e.g., lithium bis(oxalate)borate).

Claims

1. An energy storage module comprising multiple stacked energy storage units, characterized in that, The energy storage unit includes: The positive and negative electrodes have active material layers coated on the central regions of each side of their respective current collectors arranged opposite each other. A separator is located between the active material layers of the positive electrode and the negative electrode; A spacer, which is configured to surround the active material layer, seals the edges of the opposing current collectors to form a containment space for the electrolyte. The reinforcing component strengthens the uncoated portions of the current collector where the active material layer is not applied. When viewed from the relative directions of the active material layers, the current collector has uncoated portions between the spacer and the active material layers. Viewed from the aforementioned relative direction, the reinforcing member is discontinuously arranged along the uncoated portion, spanning the periphery of the active material layer and the spacer. When viewed from the relative direction, adjacent reinforcing members in the relative direction have non-overlapping portions that do not overlap with each other at the periphery of the active material layer.

2. The energy storage module according to claim 1, characterized in that, When viewed from the relative direction, the reinforcing member has an uneven portion at the periphery of the active material layer, and adjacent reinforcing members in the relative direction have non-overlapping portions at the periphery of the active material layer where the uneven portions do not overlap.

3. The energy storage module according to claim 1 or 2, characterized in that, The non-overlapping portions of the reinforcing member are not adjacent in the opposite direction.

4. The energy storage module according to claim 1 or 2, characterized in that, The spacer and the reinforcing member are formed as a single, integral component.

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