Power storage module

Abstract

To provide a power storage module that can suppress an increase in thickness due to an overlap between an electrode coating portion of a current collector and a reinforcing member, thereby suppressing a decrease in energy density as a power storage module.SOLUTION: In a power storage module according to the present disclosure, stacked power storage cells 110, 120 include a spacer 20 that seals between the edges of the opposing current collectors 10 to form a storage space for storing an electrolyte, and a reinforcing member 22 that reinforces an uncoated portion of the current collector that is not coated with an active material layer 14. The reinforcing member has a portion that is disposed along the uncoated portion so as to straddle the peripheral portion of the active material layer and the spacer. Adjacent reinforcing members in the stacking direction have non-overlapping portions that do not overlap with each other at the peripheral portion of the active material layer.SELECTED DRAWING: Figure 3A

Description

[Technical field]

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

[0002] Patent Document 1 discloses a storage cell including a positive electrode, a negative electrode, a separator, a spacer, and a reinforcing member. The positive electrode and the negative electrode have an active material layer on one side of a current collector made of metal foil. The positive electrode and the negative electrode are arranged so that the active material layers face each other. The separator is arranged between the positive electrode and the negative electrode and is interposed between the active material layers. The spacer is arranged between the positive electrode and the negative electrode, and seals the edge portion of the current collector so as to surround the active material layer, forming a storage space in which an electrolyte is stored. The reinforcing member reinforces an uncoated portion of the current collector where the active material layer is not located. When viewed from the opposing direction of the active material layers of the positive electrode and the negative electrode, the current collector has the uncoated portion between the spacer and the active material layer. The reinforcing member is arranged along the uncoated portion so as to span 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 opposing direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-069042 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to prevent the current collector foil from breaking or bending due to reduced pressure or thermal shock, a reinforcing member may be disposed across the periphery of the electrode and the electrode coated portion to increase the strength of the entire electrode body. FIG. 5 shows an example in which the thickness increases due to the overlap of the reinforcing member when a part of the spacer is disposed across the periphery of the electrode and the electrode coated portion as a reinforcing member. As shown in FIG. 5, the thickness increases at the overlapping portion 40 where the electrode coated portion (negative electrode 14) of the current collector 10 and the reinforcing member 22B (part of the spacer 20) overlap. In an electricity storage module (hereinafter, sometimes simply referred to as a "module") in which multiple such electrode bodies are stacked, the increase in thickness of the overlapping portion 40 becomes significant, and there is a risk of the energy density of the module decreasing.

[0005] An object of the present disclosure is to provide an electricity storage module that can suppress an increase in thickness due to the overlapping portion between the electrode coating portion of the current collector and a reinforcing member, thereby suppressing a decrease in energy density as an electricity storage module. [Means for solving the problem]

[0006] The means for solving the above problems include the following embodiments. <1> A storage module in which a plurality of storage cells are stacked, The storage cell is a positive electrode and a negative electrode in which active material layers are coated in a central region of one surface of opposing current collectors and disposed so as to face each other; a separator interposed between the active material layers of the positive electrode and the negative electrode; a spacer that is disposed so as to surround the active material layer and seals a gap between the edges of the opposing current collectors to form a storage space for storing an electrolyte; a reinforcing member that reinforces an uncoated portion of the current collector that is not coated with the active material layer, When viewed from a direction in which the active material layers face each other, the current collector has an uncoated portion between the spacer and the active material layer, When viewed from the opposing direction, the reinforcing member has a portion that is disposed along the uncoated portion so as to straddle a peripheral edge portion of the active material layer and the spacer, When viewed from the opposing direction, the reinforcing members adjacent to each other in the opposing direction have non-overlapping portions that do not overlap with each other in the peripheral portions of the active material layers. Energy storage module. <2> When viewed from the opposing direction, the reinforcing member has an uneven portion in a peripheral portion of the active material layer, and the reinforcing members adjacent to each other in the opposing direction have a non-overlapping portion in which the uneven portions do not overlap with each other in the peripheral portions of the active material layer. <1> The power storage module according to claim 1. <3> The non-overlapping portions of the reinforcing members are not adjacent to each other in the opposing direction. <1> or <2> The power storage module according to claim 1. <4> The spacer and the reinforcing member are integrally formed as the same member. <1> ~ <3> 13. The power storage module according to claim 12, Effect of the Invention

[0007] According to the present disclosure, there is provided an electricity storage module that can suppress an increase in thickness due to an overlap between an electrode coating portion of a current collector and a reinforcing member, thereby suppressing a decrease in energy density as an electricity storage module. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic perspective view showing an example of the appearance of an electricity storage module according to the present disclosure. [Diagram 2] 1 is a schematic diagram showing an example of an energy storage module configured by alternately stacking energy storage cells having comb-tooth-shaped spacers. FIG. [Figure 3A] FIG. 3 is a schematic cross-sectional view taken along the line AA′ in FIG. 2. [Figure 3B] FIG. 3 is a schematic cross-sectional view of the line BB′ in FIG. 2. [Figure 4] FIG. 13 is a schematic diagram showing a structure in which reinforcing members (parts of a spacer) are alternately arranged in partition layers so as not to overlap each other. [Diagram 5]FIG. 13 is a schematic diagram showing an example of an increase in thickness due to an overlapping portion of a reinforcing member (a part of a spacer). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the energy storage module according to the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the reference numerals will be omitted as appropriate in the same drawings, and the description will also be omitted as appropriate.

[0010] The energy storage module according to the present disclosure has a configuration in which the reinforcing members are stacked such that the overlapping portions where the electrode coating portions (active material layers) and the reinforcing members overlap in the stacking direction of the multiple energy storage cells are discontinuous in the stacking direction, thereby mitigating the increase in thickness when the energy storage cells are stacked, and suppressing a decrease in the energy density of the module.

[0011] FIG. 1 is a schematic perspective view showing an example of the appearance of an electricity storage module according to the present disclosure. The electricity storage module 100 according to the present disclosure is a rectangular parallelepiped object, as shown in FIG. 1, for example. The electricity storage module 100 includes an electrode stack 102 including a stacked bipolar electrode group, a resin body 104 surrounding and holding the side surface of the electrode stack 102, and an electrolyte (not shown). The electricity storage module 100 according to the present disclosure has a configuration in which a plurality of electricity storage cells are stacked. The length and width of the electricity storage module 100 are not particularly limited, but each may be more than 1 m.

[0012] The energy storage cell includes a positive electrode and a negative electrode formed on one surface of each of opposing current collectors, a separator, a spacer, and a reinforcing member. The reinforcing member reinforces an uncoated portion of the current collector where the active material layer of the positive electrode or the negative electrode is not coated. The reinforcing member may be a member different from the spacer, or may be the same member integrated with the spacer, that is, the spacer and the reinforcing member may be integrally formed. Hereinafter, as an example of the energy storage module according to the present disclosure, an embodiment in which the spacer and the reinforcing member are integrally formed will be described.

[0013] Fig. 2 shows an electricity storage module 100 configured by alternately stacking electricity storage cells 110, 120. Fig. 3A is a schematic cross-sectional view showing a cross section along line AA' in Fig. 2, and Fig. 3B is a schematic cross-sectional view showing a cross section along line BB' in Fig. 2. Note that, for ease of explanation, the positive electrode 12, separator 16, and seal portion 18 are omitted in Fig. 2.

[0014] The energy storage cell 110 includes a positive electrode 12 and a negative electrode 14 formed on one surface of the opposing current collectors 10, a separator 16, a spacer 20A, and a reinforcing member 22A. The energy storage cell 120 includes a positive electrode 12 and a negative electrode 14 formed on one surface of the opposing current collectors 10, a separator 16, a spacer 20B, and a reinforcing member 22B.

[0015] The positive electrode 12 and the negative electrode 14 are formed by applying active material layers to the central region of one surface of each of the opposing current collectors 10 so as to face each other. The separator 16 is interposed between the active material layers 12, 14 of the positive electrode 12 and the negative electrode 14 (between the positive electrode 12 and the negative electrode 14). Spacers 20A, 20B are disposed so as to surround active material layers 12, 14, and seal the space between the edges of opposing current collectors 10 to form a storage space T for storing an electrolyte. When viewed from the direction in which the active material layers 12, 14 face each other (the same as the stacking direction of the electricity storage cells 110, 120), the current collector 10 has uncoated portions between the spacers 20A, 20B and the active material layers 12, 14. Reinforcing members 22A, 22B reinforce uncoated portions of current collector 10 that are not coated with active material layers 12, 14. When viewed from the opposing direction of active material layers 12, 14, reinforcing members 22A, 22B have portions that are disposed along the uncoated portions so as to straddle the peripheral edges of active material layers 12, 14 and spacers 20A, 20B.

[0016] In this embodiment, the spacer 20A and the reinforcing member 22A, and the spacer 20B and the reinforcing member 22B are each formed as an integral member. 2, the spacers 20A, 20B in each of the power storage cells 110, 120 have an uneven shape (sometimes referred to as a "comb-tooth shape") when viewed from the opposing direction (the same as the stacking direction). In the spacers 20A, 20B having such a comb-tooth shape, the recesses function as the spacers 20A, 20B for forming the storage space T for the electrolyte, and the protrusions function as reinforcing members 22A, 22B for reinforcing the uncoated portions where the active material layer 14 is not coated.

[0017] In this embodiment, comb-tooth shaped spacers 20A, 20B are arranged in the space on the positive electrode 12 side, and the ends of the reinforcing members 22A, 22B overlap the periphery on the negative electrode 14 side. By alternately stacking the power storage cells 110, 120 in this manner, the overlap between the reinforcing member (comb-tooth portion) 22 and the negative electrode 14 does not accumulate in the stacking direction, and the bulge inside the module is mitigated, reducing the unevenness of the module. The total thickness of the module does not increase, and the decrease in energy density is suppressed. In addition, the space is necessary for gas generation due to charging and discharging, and by forming the spacers 20A, 20B in a comb-tooth shape, there is also an advantage that the space (accommodating space) Y can be secured widely.

[0018] The storage cells 110, 120 are configured such that, when the storage cells 110, 120 are alternately stacked, the position of the convex portion of the spacer of one storage cell is the position of the concave portion of the spacer of the other storage cell. Therefore, by stacking the storage cells 110, 120 alternately to configure a storage module, the convex portions of the spacers functioning as reinforcing members of the storage cells 110, 120 adjacent to each other in the stacking direction do not overlap continuously in the stacking direction. When the storage cells 110, 120 are alternately stacked, the reinforcing members 22A, 22B adjacent to each other in the facing direction (stacking direction) have non-overlapping portions in which the concave and convex portions do not overlap at the periphery of the active material layers 12, 14. Therefore, when the storage cells are stacked, the increase in thickness due to the overlap of the reinforcing members in the stacking direction is mitigated, and the decrease in the energy density of the module is suppressed.

[0019] Although the recesses of the reinforcing members 22A, 22B form non-overlapping portions, even if the recesses of the reinforcing members 22A, 22B are adjacent to each other in the opposing direction when the power storage cells 110, 120 are stacked, there is no effect of suppressing accumulation of overlaps between the reinforcing members 22 and the negative electrodes 14. For this reason, it is preferable that the non-overlapping portions (recesses) of the reinforcing members 22A, 22B are not adjacent to each other in the opposing direction.

[0020] The method for manufacturing the energy storage module 100 according to the present disclosure is not particularly limited. The energy storage module according to the present disclosure can be manufactured by sequentially stacking the electrode body and the spacer. An example of the method for manufacturing the energy storage module according to the present disclosure will be described below. FIG. 4 shows an example of the method for manufacturing the energy storage module according to the present disclosure.

[0021] First, as shown in FIG. 4(A), electrode assemblies having seal parts 18 welded to the outer periphery of collector 10 are stacked. Next, as shown in FIG. 4(B), separator 16 is stacked on negative electrode 14. Next, comb-tooth shaped spacers 20 are stacked as shown in FIG. 4(C). Comb-tooth shaped spacers 20 are alternately arranged by separator layers so that comb-tooth parts (reinforcement members) of adjacent cells do not overlap in the stacking direction. Next, electrode assemblies having seal parts 18 welded to the outer periphery are stacked as shown in FIG. 4(D). By repeating the lamination in this manner, an electricity storage module is obtained in which a plurality of electricity storage cells are stacked together and in which the accumulation of overlaps between the reinforcing members 22 and the negative electrodes 14 is suppressed.

[0022] Constituent materials, etc. of the energy storage module according to the present disclosure will be specifically described below, but the constituent materials, etc. of the energy storage module according to the present disclosure are not limited to the following description.

[0023] (Electrode laminate) The electrode stack 102 is a rectangular parallelepiped object. The electrode stack 102 includes a plurality of bipolar electrodes stacked with a separator 16 interposed therebetween. As shown in FIG. 3A and FIG. 3B, the electrode stack 102 has a plurality of bipolar electrodes, a plurality of separators 16, a positive terminal electrode (not shown), and a negative terminal electrode (not shown). The plurality of bipolar electrodes and the plurality of separators 16 are alternately stacked along the axial direction. The positive terminal electrode is stacked with the separator 16 interposed on the bipolar electrode located most on one side of the stacking direction among the plurality of bipolar electrodes. The negative terminal electrode is stacked with the separator 16 interposed on the bipolar electrode located most on the other side of the stacking direction among the plurality of bipolar electrodes.

[0024] 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 welded to a resin body 104 (seal portion 18). The positive electrode 12 is formed on one surface of the current collector 10. The negative electrode 14 is formed on the other surface of the current collector 10. The bipolar electrode may have a known configuration.

[0025] The current collector 10 supplies current to the positive electrode 12 and the negative electrode 14 during discharging or charging of the electricity storage module 100. Examples of the current collector 10 include aluminum foil, copper foil, nickel foil, titanium foil, and stainless steel foil. A coating layer may be formed on the surface of the current collector 10 by a known method (e.g., plating, spray coating, etc.). The thickness of the current collector 10 may be 1 μm to 100 μm.

[0026] The positive electrode 12 includes a positive electrode active material (e.g., a lithium composite metal oxide having a layered rock salt structure, a metal oxide having a spinel structure, a polyanion-based compound, etc.) capable of absorbing and releasing charge carriers. The positive electrode 12 may further include a conductive assistant (e.g., carbon nanofiber, etc.) for increasing electronic conductivity, a binder (e.g., polyvinylidene fluoride, etc.), an electrolyte supporting salt (lithium salt) for increasing ionic conductivity, a polymer electrolyte, and an additive (e.g., trifluoropropylene carbonate, a filler as a reinforcing material, etc.) as necessary. The thickness of the positive electrode 12 may be 2 μm to 500 μm.

[0027] The negative electrode 14 includes a negative electrode active material capable of absorbing and releasing charge carriers (e.g., carbon (e.g., natural graphite, artificial graphite), a compound capable of alloying with lithium (e.g., silicon, tin, etc.), etc.). The negative electrode 14 may further include a conductive assistant (e.g., acetylene black, etc.) for enhancing electronic conductivity, a binder (e.g., polyvinylidene fluoride, etc.), an electrolyte supporting salt (lithium salt) for enhancing ionic conductivity, a polymer electrolyte, and an additive (e.g., trifluoropropylene carbonate, a filler as a reinforcing material, etc.) as necessary. The thickness of the negative electrode 14 may be 2 μm to 500 μm. The thickness of the negative electrode 14 may be the same as or different from the thickness of the positive electrode 12. In this embodiment, as shown in FIG. 3A and FIG. 3B, the length of the negative electrode 14 is longer than the length of the positive electrode 12.

[0028] (Separator) The separator 16 maintains the distance between the positive electrode 12 and the negative electrode 14 to prevent contact short circuit, and allows charge carriers such as lithium ions (e.g., lithium ions) to pass through. The periphery of the separator 16 is welded to the resin body 104 (seal portion 18). The separator 16 is held by the resin body 104. Examples of the separator 16 include a porous resin sheet or a nonwoven fabric. Examples of the material for the porous resin sheet include polyolefin (polypropylene, polyethylene, etc.). Examples of the material for the nonwoven fabric include polypropylene, polyethylene terephthalate, methylcellulose, etc. The separator 16 may have a known configuration.

[0029] (Resin body) The resin body 104 forms a storage space T between bipolar electrodes adjacent in the stacking direction. The storage space T contains the positive electrode 12, the negative electrode 14, and the separator 16 in a state of being contained in an electrolytic solution. In this embodiment, the resin body 104 prevents the electrolytic solution contained in the storage space T from leaking to the outside. The resin body 104 can prevent moisture from entering the storage space T from the outside of the electricity storage module 100. The resin body 104 prevents internal gas generated from the positive electrode 12 or the negative electrode 14 due to charging, discharging, etc. from leaking to the outside of the electricity storage module 100.

[0030] The resin body 104 is a square tube having a rectangular cross section. The resin body 104 includes a seal portion 18 that holds the periphery of each of the current collector 10 and the separator 16, a spacer 20, a reinforcing member 22, and the like. Includes. The seal portion 18 is disposed on each of the current collector 10 and the separator 16 along the stacking direction. The seal portion 18 is a square tube with a rectangular cross section. The seal portion 18 is welded to the periphery of the current collector 10. Adjacent seal portions 18 in the stacking direction are welded to each other. Therefore, the periphery of the current collector 10 and the periphery of the separator 16 are each held in a state embedded in the resin body 104. Examples of the material of the resin body 104 (seal portion 18, spacer 20, reinforcing member 22) include polyethylene, polystyrene, acrylonitrile-butadiene-styrene copolymer synthetic resin (ABS resin, modified polypropylene, acrylonitrile-styrene resin, etc.).

[0031] (electrolyte) The electrolyte is contained in the containing space T. The electrolyte may include a non-aqueous solvent and a lithium salt. The lithium salt may be, for example, LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN(FSO 2 ) 2 , LiN(CF 3 SO 2 ) 2 Examples of the non-aqueous solvent include cyclic carbonates, cyclic esters, chain carbonates, chain esters, ethers, etc. The non-aqueous electrolyte may contain an additive (e.g., lithium bis(oxalato)borate, etc.). [Explanation of symbols]

[0032] 10 current collector, 12, 14 active material layer, 12 negative electrode, 12 positive electrode, 14 active material layer, 14 negative electrode, 16 separator, 18 seal portion, 20 spacer, 22 reinforcing member, 40 overlapping portion, 100 energy storage module, 102 electrode laminate, 104 resin body, 110, 120 energy storage cell

Claims

1. A storage module in which a plurality of storage cells are stacked, The storage cell is a positive electrode and a negative electrode in which active material layers are coated in a central region of one surface of opposing current collectors and disposed so as to face each other; a separator interposed between the active material layers of the positive electrode and the negative electrode; a spacer that is disposed so as to surround the active material layer and seals a gap between the edges of the opposing current collectors to form a storage space for storing an electrolyte; a reinforcing member that reinforces an uncoated portion of the current collector that is not coated with the active material layer, When viewed from a direction in which the active material layers face each other, the current collector has an uncoated portion between the spacer and the active material layer, When viewed from the opposing direction, the reinforcing member is intermittently disposed along the uncoated portion so as to straddle a peripheral edge portion of the active material layer and the spacer, When viewed from the opposing direction, the reinforcing members adjacent to each other in the opposing direction have non-overlapping portions that do not overlap with each other in the peripheral portions of the active material layers. Energy storage module.

2. 2. The energy storage module according to claim 1, wherein when viewed from the opposing direction, the reinforcing member has an uneven portion in a peripheral portion of the active material layer, and adjacent reinforcing members in the opposing direction have non-overlapping portions in which the uneven portions do not overlap in the peripheral portions of the active material layer.

3. The energy storage module according to claim 1 or 2, wherein the non-overlapping portions of the reinforcing members are not adjacent to each other in the opposing direction.

4. The electricity storage module according to claim 1 or 2, wherein the spacer and the reinforcing member are integrally formed as a same member.

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