Power storage module

Abstract

To provide a power storage module capable of suppressing the decrease in volume of a gas pocket.SOLUTION: A power storage module 1 includes an electrode multilayer body 10 including a plurality of bipolar electrodes 100, a positive electrode terminal electrode 200, and a negative electrode terminal electrode 300, a sealing part 500, and a buffer region formation member 600 to form a closed buffer region R2. Each bipolar electrode 100 includes a current collector 110, a positive electrode active material layer 120, and a negative electrode active material layer 130. The positive electrode terminal electrode 200 includes a positive electrode current collector foil 112 and a positive electrode active material layer 120. The negative electrode terminal electrode 300 includes a negative electrode foil 113 and a negative electrode active material layer 130. The sealing part 500 seals a region R1 in a state where a region R1 formed between a positive electrode non-applied part 112b and a negative electrode non-applied part 113b has lower pressure than atmospheric pressure. The buffer region formation member 600 forms the buffer region R2 at a position overlapping with the region R1 in a lamination direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] JP 2021-128898 A discloses an energy storage module including multiple bipolar electrodes, multiple separators arranged between adjacent bipolar electrodes, a sealing portion that seals the space formed between the adjacent bipolar electrodes, and an electrolyte solution arranged in the space. When viewed from the stacking direction, the separator has an overlapping portion that overlaps with the electrode layer of the bipolar electrode and an exposed portion that does not overlap with the electrode layer. The region where the exposed portion exists has the function of accommodating gas generated from the electrode during charge and discharge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-128898 Summary of the Invention [Problem to be solved by the invention]

[0004] In the energy storage module described in Patent Publication No. 2021-128898, the pressure inside the energy storage module may be reduced to below atmospheric pressure, in which case the electrode located outermost in the stacking direction may deform inward in the stacking direction due to the pressure difference between the inside and outside of the energy storage module.

[0005] On the other hand, the area where the exposed portion of the separator is located functions as a gas pocket that accommodates gas generated from the electrodes during charge and discharge. Therefore, if the outermost electrode in the stacking direction deforms inward, the volume of the gas pocket decreases.

[0006] An object of the present disclosure is to provide an energy storage module that can suppress a reduction in the volume of gas pockets. [Means for solving the problem]

[0007] an electrode stack including a plurality of bipolar electrodes stacked on one another, a positive terminal electrode disposed on one side of the plurality of bipolar electrodes in a stacking direction of the plurality of bipolar electrodes, and a negative terminal electrode disposed on the other side of the plurality of bipolar electrodes in the stacking direction; a sealing portion that seals between a pair of electrodes of the electrode stack that are adjacent to each other in the stacking direction; and a buffer area forming member that forms a sealed buffer area on the outside of the electrode stack in the stacking direction, wherein each of the plurality of bipolar electrodes has a current collector including a positive current collector foil and a negative current collector foil, a positive electrode active material layer provided on the positive current collector foil of the current collector, and a negative electrode active material layer provided on the negative current collector foil of the current collector, the negative electrode terminal electrode has a negative electrode foil and a negative electrode active material layer provided on the negative electrode foil, the positive electrode collector foil in each of the current collectors and the positive electrode collector foil in the positive electrode terminal electrode have a positive electrode coated portion on which the positive electrode active material layer is provided and a positive electrode uncoated portion on which the positive electrode active material layer is not provided, the negative electrode collector foil in each of the current collectors and the negative electrode collector foil in the negative electrode terminal electrode have a negative electrode coated portion on which the negative electrode active material layer is provided and a negative electrode uncoated portion facing the positive electrode uncoated portion in the stacking direction and on which the negative electrode active material layer is not provided, the sealing portion seals a region formed between the positive electrode uncoated portion and the negative electrode uncoated portion in a state where the region is at a pressure lower than atmospheric pressure, The buffer area forming member forms the buffer area at a position overlapping the region in the stacking direction. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an electricity storage module that can suppress a reduction in the volume of a gas pocket. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view schematically illustrating an electricity storage module according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 10 is a perspective view schematically illustrating an electricity storage module according to a second embodiment of the present disclosure. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present disclosure will be described with reference to the accompanying drawings, in which the same or corresponding elements are designated by the same reference numerals.

[0011] (First embodiment) Fig. 1 is a perspective view schematically illustrating an electricity storage module according to a first embodiment of the present disclosure. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in Figs. 1 and 2, the electricity storage module 1 includes an electrode stack 10, a plurality of separators 400, a sealing portion 500, and a buffer area-forming member 600.

[0012] The electrode stack 10 includes a plurality of bipolar electrodes 100 , a positive terminal electrode 200 , and a negative terminal electrode 300 .

[0013] The bipolar electrodes 100 are stacked one on top of another. As shown in FIG. 2, each bipolar electrode 100 includes a current collector 110, a positive electrode active material layer 120, and a negative electrode active material layer .

[0014] The current collector 110 is made of metal and is formed, for example, in a rectangular shape. The current collector 110 has a positive electrode current collector foil 112 and a negative electrode current collector foil 113. The positive electrode current collector foil 112 is made of, for example, aluminum. The negative electrode current collector foil 113 is made of, for example, copper foil. The negative electrode current collector foil 113 is adhered to the positive electrode current collector foil 112 with a conductive adhesive.

[0015] The positive electrode active material layer 120 is provided on one surface of the current collector 110, i.e., on the surface of the positive electrode current collector foil 112. The negative electrode active material layer 130 is provided on the other surface of the current collector 110, i.e., on the surface of the negative electrode current collector foil 113.

[0016] The plurality of bipolar electrodes 100 are stacked such that the positive electrode active material layer 120 of one bipolar electrode 100 and the negative electrode active material layer 130 of the bipolar electrode 100 adjacent to the one bipolar electrode 100 face each other.

[0017] The positive terminal electrode 200 is disposed on one side of the plurality of bipolar electrodes 100 in the stacking direction. The positive terminal electrode 200 has a positive current collector foil 112 and a positive active material layer 120 provided on the positive current collector foil 112. The configurations of the positive current collector foil 112 and the positive active material layer 120 in the positive terminal electrode 200 are the same as those in the bipolar electrode 100.

[0018] The negative terminal electrode 300 is disposed on the other side of the plurality of bipolar electrodes 100 in the stacking direction. The negative electrode terminal electrode 300 has a negative electrode current collector foil 113 and a negative electrode active material layer 130 provided on the negative electrode current collector foil 113. The configurations of the negative electrode current collector foil 113 and the negative electrode active material layer 130 in the negative electrode terminal electrode 300 are the same as those in the bipolar electrode 100.

[0019] The positive electrode current collector foil 112 in each bipolar electrode 100 and the positive electrode current collector foil 112 in the positive terminal electrode 200 have a positive electrode coated portion 112a and a positive electrode uncoated portion 112b.

[0020] The positive electrode coated portion 112a is a portion where the positive electrode active material layer 120 is provided.

[0021] The positive electrode uncoated portion 112b is a portion where the positive electrode active material layer 120 is not provided, that is, a portion where the positive electrode current collector foil 112 is exposed.

[0022] The negative electrode current collector foil 113 in each bipolar electrode 100 and the negative electrode current collector foil 113 in the negative terminal electrode 300 have a negative electrode coated portion 113a and a negative electrode uncoated portion 113b.

[0023] The negative electrode coated portion 113a is a portion where the negative electrode active material layer 130 is provided.

[0024] The negative electrode uncoated portion 113b is a portion where the negative electrode active material layer 130 is not provided, that is, a portion where the negative electrode current collector foil 113 is exposed. The negative electrode uncoated portion 113b faces the positive electrode uncoated portion 112b in the stacking direction.

[0025] Each separator 400 is disposed between a pair of electrodes 100, 200, 300 adjacent to each other in the stacking direction. Specifically, each separator 400 is disposed between a positive electrode active material layer 120 and a negative electrode active material layer 130. Each separator 400 is made of an insulating material and allows ions to pass through. Examples of each separator 400 include a polyolefin microporous membrane.

[0026] The sealing portion 500 is made of an insulating material (e.g., resin). The sealing portion 500 seals a pair of electrodes 100, 200, and 300 adjacent to each other in the stacking direction of the electrode stack 10. More specifically, the sealing portion 500 seals a region R1 (see FIG. 2 ) formed between the positive electrode uncoated portion 112b and the negative electrode uncoated portion 113b when the region R1 is at a pressure lower than atmospheric pressure. An electrolyte is sealed in this region R1. The sealing portion 500 holds the peripheral edges of the current collector foils 112 and 113 and the peripheral edges of the separators 400. The sealing portion 500 prevents leakage of the electrolyte from the region R1 and infiltration of moisture from the outside into the region R1, and also ensures a gap between the positive electrode uncoated portion 112b and the negative electrode uncoated portion 113b, which are arranged to sandwich the region R1. The region R1 functions as a gas pocket that stores gas generated from each of the electrodes 100, 200, and 300 during charging and discharging.

[0027] The buffer area-forming member 600 forms a sealed buffer area R2 (see FIG. 2) outside the electrode stack 10 in the stacking direction. As shown in FIG. 2, the buffer area-forming member 600 forms the buffer area R2 at a position overlapping with the region R1 in the stacking direction. The buffer area-forming member 600 has a positive electrode side conductive member 612, a positive electrode side conductive film 622, a positive electrode side holding portion 632, a positive electrode side support portion 642, a negative electrode side conductive member 613, a negative electrode side conductive film 623, a negative electrode side holding portion 633, and a negative electrode side support portion 643.

[0028] The positive electrode side conductive member 612 is disposed so as to be in contact with the outer surface of the positive electrode coated portion 112a of the positive electrode terminal electrode 200. The positive electrode side conductive member 612 is formed in a flat plate shape. The positive electrode side conductive member 612 is made of aluminum, copper, or the like.

[0029] The positive electrode side conductive film 622 covers the positive electrode side conductive member 612. The positive electrode side conductive film 622 covers the entire outer surface of the positive electrode side conductive member 612. The positive electrode side conductive film 622 is made of aluminum or the like.

[0030] The positive electrode side holding portion 632 holds the peripheral edge of the positive electrode side conductive film 622 so as to form a buffer area R2 together with the positive electrode uncoated portion 112b of the positive electrode terminal electrode 200, the positive electrode side conductive member 612, and the positive electrode side conductive film 622. The positive electrode side holding portion 632 is made of an insulating material (such as resin). The positive electrode side holding portion 632 is connected to the outer end surface of the sealing portion 500 in the stacking direction. The positive electrode side holding portion 632 may be made of the same material as the sealing portion 500 and may be formed integrally with the sealing portion 500.

[0031] As shown in FIG. 2, the portion of the positive electrode side conductive film 622 that defines the buffer area R2 (the portion between the positive electrode side conductive member 612 and the positive electrode side holding portion 632) is deformed inward in the stacking direction due to the pressure difference between atmospheric pressure and the pressure in the region R1.

[0032] The positive electrode side support portion 642 is disposed between the positive electrode uncoated portion 112b of the positive electrode terminal electrode 200 and the positive electrode side conductive film 622. The positive electrode side support portion 642 supports the positive electrode side conductive film 622. The positive electrode side support portion 642 is made of an insulating material (e.g., resin). The positive electrode side support portion 642 has a shape extending from the positive electrode side holding portion 632 toward the positive electrode side conductive member 612. The positive electrode side support portion 642 may be made of the same material as the positive electrode side holding portion 632 and may be formed integrally with the positive electrode side holding portion 632. The positive electrode side support portion 642 is set to have sufficient rigidity to support the positive electrode side conductive film 622 that is deformed inward in the stacking direction. The positive electrode side support portion 642 may be in contact with the positive electrode uncoated portion 112b of the positive electrode terminal electrode 200 or may be spaced apart from the positive electrode uncoated portion 112b.

[0033] The negative electrode side conductive member 613, the negative electrode side conductive film 623, the negative electrode side holding portion 633, and the negative electrode side support portion 643 have configurations corresponding to the positive electrode side conductive member 612, the positive electrode side conductive film 622, the positive electrode side holding portion 632, and the positive electrode side support portion 642, respectively. Therefore, the description of the negative electrode side conductive member 613, the negative electrode side conductive film 623, the negative electrode side holding portion 633, and the negative electrode side support portion 643 will be simplified.

[0034] The negative electrode conductive member 613 is disposed so as to contact the outer surface of the negative electrode coated portion 113 a of the negative terminal electrode 300 .

[0035] The negative electrode conductive film 623 covers the negative electrode conductive member 613 .

[0036] The negative electrode side holding portion 633 holds the peripheral edge of the negative electrode side conductive film 623 so as to form a buffer area R2 together with the negative electrode uncoated portion 113b of the negative electrode terminal electrode 300, the negative electrode side conductive member 613, and the negative electrode side conductive film 623.

[0037] The negative electrode support part 643 is disposed between the negative electrode uncoated part 113b of the negative electrode terminal electrode 300 and the negative electrode conductive film 623. The negative electrode support part 643 supports the negative electrode conductive film 623.

[0038] As described above, in the energy storage module 1 of this embodiment, a sealed buffer area R2 is formed at a position overlapping in the stacking direction with the sealed area R1 at a pressure lower than atmospheric pressure, and this buffer area R2 absorbs the pressure difference between atmospheric pressure and the pressure in area R1, thereby preventing the uncoated areas 112b, 113b in each terminal electrode 200, 300 from approaching the uncoated areas 112b, 113b in the bipolar electrode 100 opposite the uncoated areas 112b, 113b, i.e., preventing a decrease in the volume of the gas pocket.

[0039] Furthermore, the uncoated portions 112b, 113b of the terminal electrodes 200, 300 are prevented from coming into contact with the uncoated portions 112b, 113b of the bipolar electrode 100 that face the uncoated portions 112b, 113b (occurrence of a short circuit).

[0040] (Second embodiment) Next, a power storage module 1 according to a second embodiment of the present disclosure will be described with reference to Figures 3 and 4. Note that in the second embodiment, only the parts that are different from the first embodiment will be described, and the description of the same structure, action, and effect as the first embodiment will not be repeated.

[0041] In this embodiment, the buffer area forming member 600 includes a cover 650 and a seal portion 660 .

[0042] The cover 650 covers the sealing portion 500. The cover 650 is made of a so-called aluminum laminate film. That is, the cover 650 has an aluminum layer 651 and a resin layer 652 that covers the front and back surfaces of the aluminum layer 651. The cover 650 has an inner edge portion 654 formed at a position that overlaps the positive electrode coated portion 112a and the negative electrode coated portion 113a in the stacking direction. In other words, the cover 650 covers the entire outer surface of the positive electrode uncoated portion 112b of the positive electrode terminal electrode 200 and the entire outer surface of the negative electrode uncoated portion 113b of the negative electrode terminal electrode 300.

[0043] The sealing portion 660 connects the cover 650 to the electrode stack 10. Specifically, the sealing portion 660 connects the inner edge portion 654 to the positive electrode coated portion 112a of the positive terminal electrode 200 and the negative electrode coated portion 113a of the negative terminal electrode 300.

[0044] It will be appreciated by those skilled in the art that the exemplary embodiments and examples described above are examples of the following aspects.

[0045] [Aspect 1] an electrode stack including a plurality of bipolar electrodes stacked on one another, a positive terminal electrode arranged on one side of the plurality of bipolar electrodes in a stacking direction of the plurality of bipolar electrodes, and a negative terminal electrode arranged on the other side of the plurality of bipolar electrodes in the stacking direction; a sealing portion that seals between a pair of electrodes adjacent to each other in the stacking direction of the electrode stack; a buffer area forming member that forms a sealed buffer area on the outside of the electrode stack in the stacking direction, Each of the plurality of bipolar electrodes a current collector including a positive electrode current collector foil and a negative electrode current collector foil; a positive electrode active material layer provided on the positive electrode current collecting foil of the current collector; a negative electrode active material layer provided on the negative electrode current collecting foil of the current collector, The positive terminal electrode is a positive electrode current collecting foil; a positive electrode active material layer provided on the positive electrode current collector foil, The negative terminal electrode is A negative electrode foil; a negative electrode active material layer provided on the negative electrode foil, The positive electrode current collecting foil in each current collector and the positive electrode current collecting foil in the positive terminal electrode are a positive electrode coating portion provided with the positive electrode active material layer; a positive electrode uncoated portion on which the positive electrode active material layer is not provided, The negative electrode current collecting foil in each current collector and the negative electrode current collecting foil in the negative terminal electrode are a negative electrode coating portion provided with the negative electrode active material layer; a negative electrode uncoated portion facing the positive electrode uncoated portion in the stacking direction and on which the negative electrode active material layer is not provided, the sealing portion seals a region formed between the positive electrode uncoated portion and the negative electrode uncoated portion in a state in which the region is under a pressure lower than atmospheric pressure, The buffer area forming member forms the buffer area at a position overlapping the region in the stacking direction.

[0046] In this energy storage module, a sealed buffer area is formed at a position overlapping the sealed area in the stacking direction when the pressure is lower than atmospheric pressure, and this buffer area absorbs the pressure difference between atmospheric pressure and the pressure within the area, thereby preventing the uncoated area of ​​each terminal electrode from approaching the uncoated area of ​​the bipolar electrode opposite the uncoated area, i.e., preventing a decrease in the volume of the gas pocket.

[0047] [Aspect 2] The buffer area forming member is a positive electrode-side conductive member arranged to contact the outer surface of the positive electrode coated portion of the positive electrode terminal electrode; a positive electrode-side conductive film that covers the positive electrode-side conductive member; a positive electrode-side holding portion that holds a peripheral portion of the positive electrode-side conductive film so as to form the buffer area together with the positive electrode uncoated portion of the positive electrode terminal electrode, the positive electrode-side conductive member, and the positive electrode-side conductive film; a negative electrode-side conductive member arranged to contact the outer surface of the negative electrode coated portion of the negative electrode terminal electrode; a negative electrode conductive film covering the negative electrode conductive member; a negative-electrode holding portion that holds a peripheral portion of the negative-electrode-side conductive film so as to form the buffer area together with the negative-electrode uncoated portion of the negative-electrode terminal electrode, the negative-electrode-side conductive member, and the negative-electrode-side conductive film.

[0048] In this embodiment, the positive electrode conductive film and the negative electrode conductive film are deformed inward in the stacking direction, thereby absorbing the compressive force due to atmospheric pressure, thereby effectively suppressing a decrease in the volume of the gas pocket.

[0049] Furthermore, since the outer surface of the energy storage module in the stacking direction is made up of a positive electrode conductive film and a negative electrode conductive film, it is possible to stack multiple energy storage modules via conductive members (such as current collector plates).

[0050] [Aspect 3] a positive electrode-side support portion disposed between the positive electrode uncoated portion of the positive electrode terminal electrode and the positive electrode-side conductive film, and supporting the positive electrode-side conductive film; 3. The energy storage module of claim 2, further comprising: a negative electrode support portion disposed between the negative electrode uncoated portion of the negative electrode terminal electrode and the negative electrode conductive film, the negative electrode support portion supporting the negative electrode conductive film.

[0051] In this embodiment, each conductive film is supported by each supporting portion, so that reduction in the volume of the gas pocket is more reliably suppressed.

[0052] [Aspect 4] The buffer area forming member is a cover that covers the sealing portion; a seal portion that connects the cover to the electrode stack, the cover has an inner edge portion formed at a position overlapping the positive electrode coated portion and the negative electrode coated portion in the stacking direction, 2. The energy storage module according to claim 1, wherein the sealing portion connects the inner edge portion to the electrode stack.

[0053] In this embodiment, the compressive force due to atmospheric pressure is absorbed by the portion of the cover that overlaps with the region in the stacking direction deforming inward in the stacking direction.

[0054] Furthermore, by disposing a conductive member (such as a current collector plate) on the portion of each terminal electrode that is not covered by the cover, it becomes possible to stack a plurality of power storage modules.

[0055] It should be noted that the embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0056] 1 Energy storage module, 10 Electrode laminate, 100 Bipolar electrode, 110 Current collector, 112 Positive electrode current collector foil, 112a Positive electrode coated portion, 112b Positive electrode uncoated portion, 113 Negative electrode current collector foil, 113a Negative electrode coated portion, 113b Negative electrode uncoated portion, 120 Positive electrode active material layer, 130 Negative electrode active material layer, 200 positive electrode terminal electrode, 300 negative electrode terminal electrode, 400 separator, 500 sealing portion, 600 buffer area forming member, 612 positive electrode side conductive member, 613 negative electrode side conductive member, 622 positive electrode side conductive film, 623 negative electrode side conductive film, 632 positive electrode side holding portion, 633 negative electrode side holding portion, 642 positive electrode side support portion, 643 negative electrode side support portion, 650 cover, 654 inner edge portion, 660 sealing portion, R1 region, R2 buffer area.

Claims

1. an electrode stack including a plurality of bipolar electrodes, a positive terminal electrode, and a negative terminal electrode; a sealing portion that seals between a pair of electrodes adjacent to each other in a stacking direction of the electrode stack; a buffer area forming member that forms a sealed buffer area on the outside of the electrode stack in the stacking direction, the positive electrode current collecting foil of each of the bipolar electrodes and the positive electrode current collecting foil of the positive terminal electrode have a positive electrode coated portion and a positive electrode uncoated portion, the negative electrode current collecting foil of each of the bipolar electrodes and the negative electrode current collecting foil of the negative terminal electrode have a negative electrode coated portion and a negative electrode uncoated portion, the sealing portion seals a region formed between the positive electrode uncoated portion and the negative electrode uncoated portion in a state in which the region is under a pressure lower than atmospheric pressure, The buffer area forming member forms the buffer area at a position overlapping the region in the stacking direction.

2. The buffer area forming member is a positive electrode-side conductive member arranged to contact the outer surface of the positive electrode coated portion of the positive electrode terminal electrode; a positive electrode-side conductive film that covers the positive electrode-side conductive member; a positive electrode-side holding portion that holds a peripheral portion of the positive electrode-side conductive film so as to form the buffer area together with the positive electrode uncoated portion of the positive electrode terminal electrode, the positive electrode-side conductive member, and the positive electrode-side conductive film; a negative electrode-side conductive member arranged to contact the outer surface of the negative electrode coated portion of the negative electrode terminal electrode; a negative electrode conductive film covering the negative electrode conductive member; a negative electrode-side holding portion that holds a peripheral edge of the negative electrode-side conductive film so as to form the buffer area together with the negative electrode uncoated portion of the negative electrode terminal electrode, the negative electrode-side conductive member, and the negative electrode-side conductive film.

3. a positive electrode-side support portion disposed between the positive electrode uncoated portion of the positive electrode terminal electrode and the positive electrode-side conductive film, and supporting the positive electrode-side conductive film; 3. The energy storage module according to claim 2, further comprising: a negative electrode support portion disposed between the negative electrode uncoated portion of the negative electrode terminal electrode and the negative electrode conductive film, the negative electrode support portion supporting the negative electrode conductive film.

4. The buffer area forming member is a cover that covers the sealing portion; a seal portion that connects the cover to the electrode stack, the cover has an inner edge portion formed at a position overlapping the positive electrode coated portion and the negative electrode coated portion in the stacking direction, The energy storage module according to claim 1 , wherein the sealing portion connects the inner edge portion to the electrode stack.

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