Energy storage module

Abstract

To provide a power storage module in which occurrence of short-circuiting in a case where an internal pressure is reduced to be lower than an atmospheric pressure can be suppressed while decrease in energy density and damage of a sealing part are suppressed.SOLUTION: A power storage module 1 includes a plurality of bipolar electrodes 100, an outermost positive electrode 200, an outermost negative electrode 300, a first sealing part 410, a second sealing part 420, an inner sealing part 430, a first insulating member 500, a second insulating member 600, and an inner insulating member 710. At a peripheral edge part of each positive electrode current collecting foil 111, a positive electrode uncoated part 111a is formed. At a peripheral edge part of each negative electrode current collecting foil 112, a negative electrode uncoated part 112a is formed. The first insulating member 500 includes a first outer insulating part 515. The second insulating member 600 includes a second outer insulating part 615. The inner insulating member 710 includes an inner insulating part 712. A thickness of the first outer insulating part 515 and a thickness of the second outer insulating part 615 are larger than a thickness of the inner insulating part 712.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power storage module.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2021-128898 discloses a power storage module including a plurality of bipolar electrodes, a plurality of separators disposed between adjacent bipolar electrodes, a sealing portion that seals a space formed between adjacent bipolar electrodes, and an electrolytic solution disposed in the space. The separator has an overlapping portion that overlaps with an electrode layer in the bipolar electrode and an exposed portion that does not overlap with the electrode layer when viewed from the stacking direction. The region where the exposed portion exists has a function of accommodating gas generated during charge and discharge.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the power storage module described in Japanese Unexamined Patent Application Publication No. 2021-128898, the inside of the power storage module may be depressurized until it becomes less than atmospheric pressure. In this case, the electrode disposed most outward in the stacking direction may be deformed inward due to the differential pressure between the inside and the outside of the power storage module. If a foreign object such as a metal piece exists in the deformed region of the outermost electrode, that is, in the region where the exposed portion of the separator exists, there is a concern that the foreign object may penetrate the separator and the pair of electrodes disposed so as to sandwich the exposed portion may come into contact with each other.

[0005] To avoid the short circuits described above, one could consider increasing the thickness of each separator. However, doing so would reduce the volume of the region where the exposed portion exists that can contain the gas generated during charging and discharging, raising concerns that the seal may break due to increased pressure in that region. Alternatively, to avoid high pressure in this region, one could consider reducing the area of ​​the electrode layer, but doing so would decrease the energy density.

[0006] The purpose of this disclosure is to provide an energy storage module that can suppress short circuits when the internal pressure is reduced to a level lower than atmospheric pressure, while suppressing a decrease in energy density and damage to the sealing portion. [Means for solving the problem]

[0007] A storage module according to one aspect of the present disclosure includes a plurality of bipolar electrodes stacked on top of each other, an outermost positive electrode disposed on one of the outermost bipolar electrodes in the stacking direction of the plurality of bipolar electrodes, an outermost negative electrode disposed on the other outermost bipolar electrode in the stacking direction of the plurality of bipolar electrodes, a first sealing portion that seals the first outer region formed between the outermost positive electrode and the bipolar electrode of the plurality of bipolar electrodes that faces the outermost positive electrode when the pressure of the first outer region is lower than atmospheric pressure, and the outermost negative electrode and the plurality of bipolar electrodes - A second sealing portion that seals the second outer region formed between the outermost negative electrode and the bipolar electrode facing the outermost negative electrode of the bipolar electrode when the pressure of the second outer region is lower than atmospheric pressure, an inner sealing portion that seals the inner region formed between a pair of bipolar electrodes adjacent to each other in the stacking direction when the pressure of the inner region is lower than atmospheric pressure, a first insulating member that insulates the outermost positive electrode from the bipolar electrode facing the outermost positive electrode among the plurality of bipolar electrodes, and the outermost negative electrode from the bipolar electrode facing the outermost negative electrode among the plurality of bipolar electrodes The system comprises a second insulating member that insulates between the bipolar electrodes and an inner insulating member that insulates between a pair of bipolar electrodes adjacent to each other in the stacking direction, and each of the plurality of bipolar electrodes comprises 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 collector foil in the current collector, and a negative electrode active material layer provided on the negative electrode current collector foil in the current collector, the outermost positive electrode comprises a positive electrode current collector foil and a positive electrode active material layer provided on the positive electrode current collector foil, and the outermost negative electrode comprises a negative electrode current collector foil and a negative electrode active material layer provided on the negative electrode current collector foil, The current collector has a positive electrode uncoated portion where the positive electrode active material layer is not provided, and the negative electrode uncoated portion where the negative electrode active material layer is not provided, and the negative electrode active material layer is not provided, and the negative electrode active material layer is not provided, and the negative electrode active material layer is not provided, and the negative electrode active material layer is not provided, and the region between the positive electrode uncoated portion in the outermost positive electrode and the negative electrode uncoated portion facing the positive electrode uncoated portion constitutes the first outer region.The region between the uncoated negative electrode portion and the uncoated positive electrode portion facing the uncoated negative electrode portion of the outermost negative electrode constitutes the second outer region, and the region between the uncoated positive electrode portion and the uncoated negative electrode portion of a pair of adjacent bipolar electrodes facing each other in the stacking direction constitutes the inner region. The first insulating member includes a first outer insulating portion disposed in the first outer region, the second insulating member includes a second outer insulating portion disposed in the second outer region, and the inner insulating member includes an inner insulating portion disposed in the inner region. The thickness of the first outer insulating portion and the thickness of the second outer insulating portion are greater than the thickness of the inner insulating portion. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide an energy storage module that can suppress a decrease in energy density and damage to the sealing portion, while also suppressing short circuits when the internal pressure is reduced to a level lower than atmospheric pressure. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing an energy storage module in the first embodiment of the present disclosure. [Figure 2] This is a cross-sectional view that schematically shows the state in which each region is under reduced pressure. [Figure 3] This is a schematic cross-sectional view showing a storage module in a second embodiment of the present disclosure. [Figure 4] This table shows examples, comparative examples, and their evaluation results. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described with reference to the drawings. In the drawings referred to below, the same or equivalent components are given the same number.

[0011] (First Embodiment) Figure 1 is a schematic cross-sectional view showing a power storage module in a first embodiment of the present disclosure. As shown in Figure 1, the power storage module 1 includes a plurality of bipolar electrodes 100, an outermost positive electrode 200, an outermost negative electrode 300, a first sealing portion 410, a second sealing portion 420, an inner sealing portion 430, a first insulating member 500, a second insulating member 600, and an inner insulating member 710.

[0012] Multiple bipolar electrodes 100 are stacked on top of each other. Each bipolar electrode 100 has a current collector 110, a positive electrode active material layer 120, and a negative electrode active material layer 130.

[0013] 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 111 and a negative electrode current collector foil 112. The positive electrode current collector foil 111 is made of, for example, aluminum. The negative electrode current collector foil 112 is made of, for example, copper foil. The negative electrode current collector foil 112 is bonded to the positive electrode current collector foil 111 by a conductive adhesive.

[0014] The positive electrode active material layer 120 is provided on one surface of the current collector 110, that is, on the surface of the positive electrode current collector foil 111. The negative electrode active material layer 130 is provided on the other surface of the current collector 110, that is, on the surface of the negative electrode current collector foil 112.

[0015] Multiple bipolar electrodes 100 are arranged such that the positive electrode active material layer 120 of one bipolar electrode 100 and the negative electrode active material layer 130 of a bipolar electrode 100 adjacent to the first bipolar electrode 100 face each other.

[0016] An uncoated positive electrode portion 111a is formed at the periphery of the positive electrode current collector foil 111, where the positive electrode active material layer 120 is not provided. An uncoated negative electrode portion 112a is formed at the periphery of the negative electrode active material layer 130, where the negative electrode active material layer 130 is not provided. The uncoated negative electrode portion 112a faces the uncoated positive electrode portion 111a in the stacking direction of the multiple bipolar electrodes 100 (vertical direction in Figure 1).

[0017] The outermost positive electrode 200 is disposed on one of the outer sides of the plurality of bipolar electrodes 100 in the stacking direction. The outermost positive electrode 200 has a positive current collector foil 111 and a positive electrode active material layer 120 provided on the positive current collector foil 111. The configurations of the positive current collector foil 111 and the positive electrode active material layer 120 in the outermost positive electrode 200 are the same as those in the bipolar electrode 100.

[0018] The outermost negative electrode 300 is disposed on the other of the outer sides of the plurality of bipolar electrodes 100 in the stacking direction. The outermost negative electrode 300 has a negative current collector foil 112 and a negative electrode active material layer 130 provided on the negative current collector foil 112. The configurations of the negative current collector foil 112 and the negative electrode active material layer 130 in the outermost negative electrode 300 are the same as those in the bipolar electrode 100.

[0019] The first sealing portion 410 seals the first outer region R1 (see FIG. 1) formed between the outermost positive electrode 200 and the bipolar electrode 100 (hereinafter referred to as "bipolar electrode 102") facing the outermost positive electrode 200 among the plurality of bipolar electrodes 100 in a state where the pressure in the first outer region R1 is lower than the atmospheric pressure. The first outer region R1 is a region formed between the positive electrode non-coated portion 111a in the outermost positive electrode 200 and the negative electrode non-coated portion 112a facing the positive electrode non-coated portion 111a. This first outer region R1 is filled with an electrolytic solution. Since the pressure in the first outer region R1 is lower than the atmospheric pressure, as shown in FIG. 1, the positive electrode non-coated portion 111a in the outermost positive electrode 200 is deformed inward in the stacking direction.

[0020] The first sealing portion 410 is made of an insulating material (such as resin). The first sealing portion 410 has a function of preventing leakage of the electrolytic solution from the first outer region R1 and ingress of moisture from the outside into the first outer region R1, and a function of ensuring the interval between the positive electrode non-coated portion 111a and the negative electrode non-coated portion ១៥a arranged so as to sandwich the first outer region R1.

[0021] The second sealing portion 420 seals the second outer region R2 (see FIG. 1) formed between the outermost negative electrode 300 and the bipolar electrode 100 facing the outermost negative electrode 300 among the plurality of bipolar electrodes 100 (hereinafter referred to as "bipolar electrode 103") in a state where the pressure in the second outer region R2 is lower than the atmospheric pressure. The second outer region R2 is a region formed between the non-coated negative electrode portion 112a of the outermost negative electrode 300 and the non-coated positive electrode portion 111a facing the non-coated negative electrode portion ”. This second outer region R2 is filled with an electrolytic solution. The pressure in the second outer region R2 is the same as the pressure in the first outer region R1. Since the pressure in the second outer region R2 is lower than the atmospheric pressure, as shown in FIG. 1, the non-coated negative electrode portion 112a of the outermost negative electrode 300 is deformed inward in the stacking direction. The configuration of the second sealing portion 420 is the same as that of the first sealing portion 410.

[0022] The inner sealing portion 430 seals the inner region R3 (see FIG. 1) formed between a pair of bipolar electrodes 100 adjacent to each other in the stacking direction in a state where the pressure in the inner region R3 is lower than the atmospheric pressure. The inner region R3 is a region between the non-coated positive electrode portion 111a and the non-coated negative electrode portion 112a facing each other in the stacking direction among a pair of adjacent bipolar electrodes 100. This inner region R3 is filled with an electrolytic solution. The configuration of the inner sealing portion 430 is the same as that of the first sealing portion 410. The pressure in the inner region R3 is the same as the pressure in the first outer region R1.

[0023] The first insulating member 500 insulates between the outermost positive electrode 200 and the bipolar electrode 102. The first insulating member 500 includes a first separator 510 and a first insulating film 520.

[0024] The first separator 510 is positioned between the outermost positive electrode 200 and the bipolar electrode 102. The first separator 510 is made of an insulating material and allows ion permeability. Examples of the first separator 510 include a polyolefin microporous membrane (such as a single-layer polyethylene structure or a three-layer structure of polypropylene, polyethylene, and polypropylene). A ceramic layer may be provided on at least one surface of the polyolefin microporous membrane. The first separator 510 has a first intervening portion 511 and a first peripheral portion 512.

[0025] The first intervening portion 511 is interposed between the positive electrode active material layer 120 of the outermost positive electrode 200 and the negative electrode active material layer 130 of the bipolar electrode 102.

[0026] The first peripheral portion 512 is connected to the outer edge of the first intervening portion 511. The first peripheral portion 512 is located in the first outer region R1. The outer end of the first peripheral portion 512 is held by the first sealing portion 410. As shown in Figure 1, the first peripheral portion 512 is deformed inward in the stacking direction by being pressed by the uncoated positive electrode portion 111a, which is deformed inward in the stacking direction.

[0027] The first insulating film 520 is made of a separate component from the first separator 510. The first insulating film 520 is located in the first outer region R1. The thickness of the first insulating film 520 is set to be the same as or greater than the thickness of the first separator 510, for example. It is preferable that the first insulating film 520 is located inside the first peripheral edge 512 in the stacking direction within the first outer region R1. In Figure 1, a foreign object 10, such as a metal piece, is shown between the first peripheral edge 512 and the first insulating film 520.

[0028] The first peripheral portion 512 and the first insulating film 520 constitute a first outer insulating portion 515 located in the first outer region R1. The first outer insulating portion 515 insulates the gap between the uncoated positive electrode portion 111a and the uncoated negative electrode portion 112a, which are positioned to sandwich the first outer region R1.

[0029] The second insulating member 600 insulates the outermost negative electrode 300 from the bipolar electrode 103. The second insulating member 600 includes a second separator 610 and a second insulating film 620.

[0030] The second separator 610 is positioned between the outermost negative electrode 300 and the bipolar electrode 103. The configuration of the second separator 610 is the same as that of the first separator 510. That is, the thickness of the second separator 610 is the same as that of the first separator 510. The second separator 610 has a second intervening portion 611 and a second peripheral portion 612.

[0031] The second intervening portion 611 is interposed between the negative electrode active material layer 130 of the outermost negative electrode 300 and the positive electrode active material layer 120 of the bipolar electrode 103.

[0032] The second peripheral portion 612 is connected to the outer edge of the second intervening portion 611. The second peripheral portion 612 is located in the second outer region R2. The outer end of the second peripheral portion 612 is held by the second sealing portion 420. As shown in Figure 1, the second peripheral portion 612 is deformed inward in the stacking direction by being pressed by the uncoated negative electrode portion 112a, which is deformed inward in the stacking direction.

[0033] The second insulating film 620 is made of a separate component from the second separator 610. The second insulating film 620 is located in the second outer region R2. The configuration of the second insulating film 620 is the same as that of the first insulating film 520. It is preferable that the second insulating film 620 is located inside the second peripheral edge 612 in the stacking direction within the second outer region R2.

[0034] The second peripheral portion 612 and the second insulating film 620 constitute a second outer insulating portion 615 located in the second outer region R2. The second outer insulating portion 615 insulates the space between the uncoated positive electrode portion 111a and the uncoated negative electrode portion 112a, which are positioned to sandwich the second outer region R2.

[0035] The inner insulating member 710 insulates between a pair of bipolar electrodes 100 that are adjacent to each other in the stacking direction. The inner insulating member 710 is composed of an inner separator (hereinafter referred to as "inner separator 710") placed between a pair of bipolar electrodes 100 that are adjacent to each other in the stacking direction. The inner separator 710 has the same thickness as the first separator 510. The inner separator 710 has an inner intervening portion 711 and an inner peripheral edge portion 712.

[0036] The inner intervening portion 711 is interposed between the positive electrode active material layer 120 of one bipolar electrode 100 and the negative electrode active material layer 130 of a bipolar electrode 100 adjacent to the first bipolar electrode 100.

[0037] The inner peripheral portion 712 is connected to the inner intervening portion 711. The inner peripheral portion 712 is located in the inner region R3. The inner peripheral portion 712 constitutes the inner insulating portion (hereinafter sometimes referred to as "inner insulating portion 712").

[0038] As shown in Figure 1, the thickness of the first outer insulating portion 515 and the thickness of the second outer insulating portion 615 are greater than the thickness of the inner insulating portion 712. Note that "thickness of the first outer insulating portion 515" refers to the total thickness of the first outer insulating portion 515, that is, the sum of the thickness of the first peripheral portion 512 and the thickness of the first insulating film 520. The same applies to "thickness of the second outer insulating portion 615".

[0039] Next, we will explain the manufacturing method of the energy storage module 1.

[0040] First, each bipolar electrode 100, the outermost positive electrode 200, and the outermost negative electrode 300 are prepared and stacked via separators 510, 610, and 710, and a first insulating film 520 is placed in the first outer region R1, and a second insulating film 620 is placed in the second outer region R2.

[0041] Then, the sealing portions 410-430 are heat-welded to each uncoated positive electrode portion 111a and each uncoated negative electrode portion 112a, and electrolyte is injected into each region R1-R3 from the injection port. Figure 2 shows, for example, the state after electrolyte has been injected into each region R1-R3.

[0042] Next, the energy storage module 1 is charged to a predetermined voltage, and an SEI film is formed on the negative electrode by the decomposition of the electrolyte solvent and additives, and the by-product gas is discharged outside the energy storage module 1.

[0043] Subsequently, the liquid injection port is sealed under a reduced pressure atmosphere (an atmosphere with a pressure lower than atmospheric pressure) (reduced pressure sealing process). This completes the energy storage module 1. When this energy storage module 1 is moved from a reduced pressure atmosphere to atmospheric pressure, as shown in Figure 1, the uncoated positive electrode portion 111a of the outermost positive electrode 200 and the uncoated negative electrode portion 112a of the outermost negative electrode 300 deform inward in the stacking direction.

[0044] As described above, in the energy storage module 1 of this embodiment, the first outer region R1, the second outer region R2, and the inner region R3 are at a lower pressure than atmospheric pressure, causing the uncoated positive electrode portion 111a of the outermost positive electrode 200 and the uncoated negative electrode portion 112a of the outermost negative electrode 300 to deform inward in the stacking direction. However, because the thickness of the first outer insulating portion 515 and the thickness of the second outer insulating portion 615 are greater than the thickness of the inner insulating portion 712, even if a foreign object 10 such as a metal piece is present in the first outer region R1, the penetration of the foreign object 10 into the first outer insulating portion 515 is suppressed.

[0045] Furthermore, because the thickness of the inner insulating portion 712 is smaller than the thickness of the first outer insulating portion 515 and the second outer insulating portion 615, a volume for containing the gas generated during charging and discharging is secured in the inner region R3, thereby suppressing the inner region R3 from becoming high pressure. As a result, damage to the inner sealing portion 430 is suppressed, and the uncoated portions 111a and 112a of the bipolar electrode 100, which would otherwise be widened to avoid high pressure in the inner region R3, are suppressed, thus preventing a decrease in energy density.

[0046] In the above embodiment, the first insulating film 520 may be made of the same material as the material constituting the first sealing portion 410 and may be formed integrally with the first sealing portion 410, and the second insulating film 620 may be made of the same material as the material constituting the second sealing portion 420 and may be formed integrally with the second sealing portion 420. In this embodiment, displacement of the first insulating film 520 within the first outer region R1 and displacement of the second insulating film 620 within the second outer region R2 are suppressed.

[0047] Furthermore, the first insulating film 520 may be positioned outside the first peripheral edge 512 in the stacking direction, and the second insulating film 620 may be positioned outside the second peripheral edge 612 in the stacking direction.

[0048] (Second Embodiment) Next, with reference to Figure 3, the energy storage module 1 in the second embodiment of this disclosure will be described. In the second embodiment, only the parts that differ from the first embodiment will be described, and the same descriptions of structure, operation, and effects as in the first embodiment will not be repeated.

[0049] In this embodiment, the thickness of the first separator 510 and the thickness of the second separator 610 are greater than the thickness of the inner separator 710. Furthermore, the first outer insulating portion 515 is composed only of the first peripheral portion 512 which has a greater thickness than the inner peripheral portion 712, and the second outer insulating portion 615 is composed only of the second peripheral portion 612 which has a greater thickness than the inner peripheral portion 712. [Examples]

[0050] Next, embodiments of the energy storage module 1 will be described along with comparative examples. Examples 1-1 to 1-8 are embodiments of the second embodiment, and Examples 2-1 to 5-3 are embodiments of the first embodiment. In each embodiment and comparative example, an energy storage module having the following configuration was used.

[0051] Positive electrode current collector foil: A foil with a positive electrode on one side. Positive electrode: A slurry of PVdF binder and conductive material in NMP or aqueous solvent. Negative electrode current collector foil: A copper foil with a negative electrode on one side. Negative electrode: A slurry of SBR, CMC, and conductive material as needed, dissolved in water. Positive electrode active material layer: Li(Ni x Mn y Co z ) O2, LiFePO4, etc. Negative electrode active material layer: Natural graphite, artificial graphite, etc. Separator: Polyolefin microporous membrane (a membrane having a single layer of polyethylene and a ceramic layer). First insulating film: LDPE (low-density polyethylene), HDPE (high-density polyethylene), PP (polypropylene), polyimide.

[0052] In each example and comparative example, five foreign objects 10 were placed inside the first peripheral edge 512 in the stacking direction of the first outer region R1 of the energy storage module 1. The first outer region R1 was then depressurized in the same environment as the depressurization sealing process during the manufacturing of the energy storage module 1. The resistance between the outermost positive electrode 200 and the bipolar electrode 102 was measured, and the degree of depressurization from atmospheric pressure (differential pressure from atmospheric pressure) when the first outer insulating portion 515 broke, causing conductivity between the positive electrode current collector foil 111 of the outermost positive electrode 200 and the negative electrode current collector foil 112 of the bipolar electrode 102 was evaluated. Figure 4 is a table showing the evaluation results for each example and comparative example. The foreign objects are L-shaped metal pieces (0.6 mm in the longitudinal direction, 0.4 mm in the transverse direction). The coverage rate of the uncoated negative electrode portion 112a of the bipolar electrode 102 by the first insulating film 520 is 95%.

[0053] As shown in Examples 1-1 to 1-8 in Figure 4, in the example where the first outer insulating portion 515 is composed only of the first peripheral portion 512, it was confirmed that the degree of pressure reduction increases as the thickness of the first peripheral portion 512 increases.

[0054] Furthermore, in Examples 2-1 to 5-3, a separator having the same configuration as the comparative example and a first insulating film 520 with different thicknesses were used. As shown in these examples, even in the example where the first outer insulating portion 515 is composed of a first peripheral portion 512 and a first insulating film 520, it was confirmed that the degree of pressure reduction increases as the thickness of the first outer insulating portion 515 (thickness of the first insulating film 520) increases.

[0055] Those skilled in the art will understand that the exemplary embodiments and examples described above are specific examples of the following embodiments.

[0056] [Aspect 1] Multiple bipolar electrodes stacked on top of each other, The outermost positive electrode is positioned on one of the outermost sides of the plurality of bipolar electrodes in the stacking direction of the plurality of bipolar electrodes, The outermost negative electrode is positioned on the other side of the plurality of bipolar electrodes in the stacking direction, A first sealing portion seals the first outer region, which is formed between the outermost positive electrode and the bipolar electrode facing the outermost positive electrode among the plurality of bipolar electrodes, when the pressure of the first outer region is lower than atmospheric pressure. A second sealing portion seals the second outer region, which is formed between the outermost negative electrode and the bipolar electrode facing the outermost negative electrode among the plurality of bipolar electrodes, when the pressure of the second outer region is lower than atmospheric pressure. An inner sealing portion that seals the inner region formed between a pair of bipolar electrodes adjacent to each other in the stacking direction when the pressure of the inner region is lower than atmospheric pressure, A first insulating member that insulates the outermost positive electrode from the bipolar electrode among the plurality of bipolar electrodes that faces the outermost positive electrode, A second insulating member that insulates the outermost negative electrode from the bipolar electrode among the plurality of bipolar electrodes that faces the outermost negative electrode, It comprises an inner insulating member that insulates between a pair of bipolar electrodes adjacent to each other in the stacking direction, Each of the aforementioned bipolar electrodes is 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 collector foil in the current collector, The current collector comprises a negative electrode active material layer provided on the negative electrode current collector foil, The outermost positive electrode is, Positive electrode current collector foil, The positive electrode current collector foil has a positive electrode active material layer provided on it, The outermost negative electrode is, Negative electrode current collector foil, The negative electrode current collector foil has a negative electrode active material layer provided on it, In each of the current collectors, the peripheral edge of the positive electrode current collector foil and the peripheral edge of the positive electrode current collector foil in the outermost positive electrode have an uncoated positive electrode portion where the positive electrode active material layer is not provided. In each of the current collectors, the peripheral edge of the negative electrode current collector foil and the peripheral edge of the negative electrode current collector foil in the outermost negative electrode have a negative electrode uncoated portion that faces the positive electrode uncoated portion in the lamination direction and where the negative electrode active material layer is not provided. The region between the uncoated portion of the positive electrode and the uncoated portion of the negative electrode facing the uncoated portion of the positive electrode constitutes the first outer region. The region between the uncoated portion of the negative electrode and the uncoated portion of the positive electrode facing the uncoated portion of the negative electrode constitutes the second outer region. The region between the uncoated positive electrode portion and the uncoated negative electrode portion of a pair of adjacent bipolar electrodes that face each other in the stacking direction constitutes the inner region. The first insulating member includes a first outer insulating portion arranged in the first outer region, The second insulating member includes a second outer insulating portion arranged in the second outer region, The inner insulating member includes an inner insulating portion arranged in the inner region, A power storage module in which the thickness of the first outer insulating portion and the thickness of the second outer insulating portion are greater than the thickness of the inner insulating portion.

[0057] In this energy storage module, the first outer region, the second outer region, and the inner region are at a pressure lower than atmospheric pressure. Although the uncoated portion of the positive electrode at the outermost positive electrode and the uncoated portion of the negative electrode at the outermost negative electrode deform inward in the stacking direction, the thickness of the first outer insulating layer and the second outer insulating layer are greater than the thickness of the inner insulating layer. Therefore, even if foreign matter such as a metal fragment is present in the first outer region, it is suppressed from penetrating the first outer insulating layer.

[0058] Furthermore, because the thickness of the inner insulating layer is smaller than the thickness of the first and second outer insulating layers, a volume for containing the gas generated during charging and discharging is secured in the inner region, thus suppressing high pressure in that inner region. Therefore, damage to the inner sealing layer is suppressed, and the need to widen the uncoated areas in the bipolar electrode to avoid high pressure in the inner region, i.e., the decrease in energy density is suppressed.

[0059] [Aspect 2] The first insulating member includes a first separator disposed between the outermost positive electrode and the bipolar electrode among the plurality of bipolar electrodes that faces the outermost positive electrode. The first separator is, A first intervening portion is interposed between the positive electrode active material layer in the outermost positive electrode and the negative electrode active material layer in the bipolar electrode, It has a first peripheral portion connected to the first intervening portion and located in the first outer region, The first outer insulating portion is, The first peripheral portion and, It comprises a first insulating film which is made of a separate material from the first separator and is arranged in the first outer region, The second insulating member is disposed between the outermost negative electrode and the bipolar electrode among the plurality of bipolar electrodes that faces the outermost negative electrode, and includes a second separator having the same thickness as the first separator. The second separator is, A second intervening portion is interposed between the negative electrode active material layer in the outermost negative electrode and the positive electrode active material layer in the bipolar electrode, It has a second peripheral portion connected to the second intervening portion and located in the second outer region, The second outer insulating portion is, The second peripheral portion and, The second insulating film, which is made of a separate component from the second separator and is arranged in the second outer region, The inner insulating member is positioned between a pair of bipolar electrodes adjacent to each other in the stacking direction and includes an inner separator having the same thickness as the first separator. The inner separator comprises an inner intervening portion interposed between the positive electrode active material layer and the negative electrode active material layer in the bipolar electrode, It has an inner peripheral portion that is connected to the inner intervening portion and is located in the inner region, The energy storage module according to embodiment 1, wherein the inner insulating portion is composed of the inner peripheral portion.

[0060] In this embodiment, since the first separator, the second separator, and the inner separator have the same thickness, it is possible to use the same separator for each. Furthermore, the thickness of the first intervening portion and the thickness of the second intervening portion are reduced compared to the case where the total thickness of the first separator and the total thickness of the second separator are greater than the thickness of the inner separator.

[0061] [Aspect 3] The first insulating film is positioned inside the first peripheral edge in the stacking direction of the first outer region, The energy storage module according to embodiment 2, wherein the second insulating film is located inside the second peripheral edge in the stacking direction of the second outer region.

[0062] In this embodiment, the displacement of each insulating film due to inward deformation in the stacking direction of the uncoated portion of the positive electrode at the outermost positive electrode and the uncoated portion of the negative electrode at the outermost negative electrode is suppressed. Furthermore, compared to the case where each insulating film is positioned outside each peripheral edge in the stacking direction of each outer region, damage to the first and second peripheral edges caused by the aforementioned deformation of the uncoated portion of the positive electrode at the outermost positive electrode and the uncoated portion of the negative electrode at the outermost negative electrode is suppressed.

[0063] [Aspect 4] The first insulating film is made of the same material as the material constituting the first sealing portion and is integrally formed with the first sealing portion. The energy storage module according to embodiment 3, wherein the second insulating film is made of the same material as the material constituting the second sealing portion and is integrally formed with the second sealing portion.

[0064] In this embodiment, displacement of the first insulating film within the first outer region and displacement of the second insulating film within the second outer region are suppressed.

[0065] [Aspect 5] The first insulating member includes a first separator disposed between the outermost positive electrode and the bipolar electrode among the plurality of bipolar electrodes that faces the outermost positive electrode. The first separator is, A first intervening portion is interposed between the positive electrode active material layer in the outermost positive electrode and the negative electrode active material layer in the bipolar electrode, It has a first peripheral portion connected to the first intervening portion and located in the first outer region, The first outer insulating portion is composed of the first peripheral portion, The second insulating member is disposed between the outermost negative electrode and the bipolar electrode among the plurality of bipolar electrodes that faces the outermost negative electrode, and includes a second separator having the same thickness as the first separator. The second separator is, A second intervening portion is interposed between the negative electrode active material layer in the outermost negative electrode and the positive electrode active material layer in the bipolar electrode, It has a second peripheral portion connected to the second intervening portion and located in the second outer region, The second outer insulating portion is composed of the second peripheral portion, The inner insulating member is arranged between a pair of bipolar electrodes adjacent to each other in the stacking direction and includes an inner separator having a thickness smaller than the thickness of the first separator. The inner separator comprises an inner intervening portion interposed between the positive electrode active material layer and the negative electrode active material layer in the bipolar electrode, It has an inner peripheral portion that is connected to the inner intervening portion and is located in the inner region, The energy storage module according to embodiment 1, wherein the inner insulating portion is composed of the inner peripheral portion.

[0066] In this embodiment, the same effect as that achieved in embodiment 1 can be obtained by adjusting the thickness of each separator.

[0067] It should be noted that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments above, and further includes all modifications within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0068] 1 Energy storage module, 10 Foreign matter, 100 Bipolar electrode, 110 Current collector, 111 Positive electrode current collector foil, 111a Positive electrode uncoated portion, 112 Negative electrode current collector foil, 112a Negative electrode uncoated portion, 120 Positive electrode active material layer, 130 Negative electrode active material layer, 200 Outermost positive electrode, 300 Outermost negative electrode, 410 First sealing portion, 420 Second sealing portion, 430 Inner sealing portion, 500 First insulating member, 510 First separator, 511 First intervening portion, 512 First peripheral portion, 515 First outer insulating portion, 520 First insulating film, 600 Second insulating member, 610 Second separator, 611 Second intervening portion, 612 Second peripheral portion, 615 Second outer insulating portion, 620 Second insulating film, 710 Inner insulating member (inner separator), 711 inner intervening part, 712 inner peripheral edge part (inner insulating part), R1 first outer region, R2 second outer region, R3 inner region.

Claims

1. Multiple bipolar electrodes stacked on top of each other, The outermost positive electrode is positioned on one of the outermost sides of the plurality of bipolar electrodes in the stacking direction of the plurality of bipolar electrodes, The outermost negative electrode is positioned on the other side of the plurality of bipolar electrodes in the stacking direction, A first sealing portion seals the first outer region, which is formed between the outermost positive electrode and the bipolar electrode facing the outermost positive electrode among the plurality of bipolar electrodes, when the pressure of the first outer region is lower than atmospheric pressure. A second sealing portion seals the second outer region, which is formed between the outermost negative electrode and the bipolar electrode facing the outermost negative electrode among the plurality of bipolar electrodes, when the pressure of the second outer region is lower than atmospheric pressure. An inner sealing portion that seals the inner region formed between a pair of bipolar electrodes adjacent to each other in the stacking direction when the pressure of the inner region is lower than atmospheric pressure, A first insulating member that insulates the outermost positive electrode from the bipolar electrode among the plurality of bipolar electrodes that faces the outermost positive electrode, A second insulating member that insulates the outermost negative electrode from the bipolar electrode among the plurality of bipolar electrodes that faces the outermost negative electrode, It comprises an inner insulating member that insulates between a pair of bipolar electrodes adjacent to each other in the stacking direction, Each of the aforementioned bipolar electrodes is 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 collector foil in the current collector, The current collector comprises a negative electrode active material layer provided on the negative electrode current collector foil, The outermost positive electrode is, Positive electrode current collector foil, The positive electrode current collector foil has a positive electrode active material layer provided on it, The outermost negative electrode is, Negative electrode current collector foil, The negative electrode current collector foil has a negative electrode active material layer provided on it, In each of the current collectors, the peripheral edge of the positive electrode current collector foil and the peripheral edge of the positive electrode current collector foil in the outermost positive electrode have an uncoated positive electrode portion where the positive electrode active material layer is not provided. In each of the current collectors, the peripheral edge of the negative electrode current collector foil and the peripheral edge of the negative electrode current collector foil in the outermost negative electrode have a negative electrode uncoated portion that faces the positive electrode uncoated portion in the lamination direction and where the negative electrode active material layer is not provided. The region between the uncoated portion of the positive electrode and the uncoated portion of the negative electrode facing the uncoated portion of the positive electrode constitutes the first outer region. The region between the uncoated portion of the outermost negative electrode and the uncoated portion of the positive electrode facing the uncoated portion of the negative electrode constitutes the second outer region. The region between the uncoated positive electrode portion and the uncoated negative electrode portion of a pair of adjacent bipolar electrodes that face each other in the stacking direction constitutes the inner region. The first insulating member includes a first outer insulating portion arranged in the first outer region, The second insulating member includes a second outer insulating portion arranged in the second outer region, The inner insulating member includes an inner insulating portion arranged in the inner region, A power storage module in which the thickness of the first outer insulating portion and the thickness of the second outer insulating portion are greater than the thickness of the inner insulating portion.

2. The first insulating member includes a first separator disposed between the outermost positive electrode and the bipolar electrode among the plurality of bipolar electrodes that faces the outermost positive electrode. The first separator is, A first intervening portion is interposed between the positive electrode active material layer in the outermost positive electrode and the negative electrode active material layer in the bipolar electrode, It has a first peripheral portion connected to the first intervening portion and positioned in the first outer region, The first outer insulating portion is, The first peripheral portion and, It comprises a first insulating film, which is made of a separate component from the first separator and is arranged in the first outer region, The second insulating member is disposed between the outermost negative electrode and the bipolar electrode among the plurality of bipolar electrodes that faces the outermost negative electrode, and includes a second separator having the same thickness as the first separator. The second separator is, A second intervening portion is interposed between the negative electrode active material layer in the outermost negative electrode and the positive electrode active material layer in the bipolar electrode, It has a second peripheral portion connected to the second intervening portion and located in the second outer region, The second outer insulating portion is, The second peripheral portion and, The second insulating film, which is made of a separate component from the second separator and is arranged in the second outer region, The inner insulating member is arranged between a pair of bipolar electrodes adjacent to each other in the stacking direction and includes an inner separator having the same thickness as the first separator. The inner separator comprises an inner intervening portion interposed between the positive electrode active material layer and the negative electrode active material layer in the bipolar electrode, It has an inner peripheral portion that is connected to the inner intervening portion and is located in the inner region, The energy storage module according to claim 1, wherein the inner insulating portion is composed of the inner peripheral portion.

3. The first insulating film is positioned inside the first peripheral edge in the stacking direction within the first outer region, The energy storage module according to claim 2, wherein the second insulating film is disposed inside the second peripheral portion in the stacking direction of the second outer region.

4. The first insulating film is made of the same material as the material constituting the first sealing portion and is integrally formed with the first sealing portion. The energy storage module according to claim 3, wherein the second insulating film is made of the same material as the material constituting the second sealing portion and is integrally formed with the second sealing portion.

5. The first insulating member includes a first separator disposed between the outermost positive electrode and the bipolar electrode among the plurality of bipolar electrodes that faces the outermost positive electrode. The first separator is, A first intervening portion is interposed between the positive electrode active material layer in the outermost positive electrode and the negative electrode active material layer in the bipolar electrode, It has a first peripheral portion connected to the first intervening portion and positioned in the first outer region, The first outer insulating portion is composed of the first peripheral portion, The second insulating member is disposed between the outermost negative electrode and the bipolar electrode among the plurality of bipolar electrodes that faces the outermost negative electrode, and includes a second separator having the same thickness as the first separator. The second separator is, A second intervening portion is interposed between the negative electrode active material layer in the outermost negative electrode and the positive electrode active material layer in the bipolar electrode, It has a second peripheral portion connected to the second intervening portion and located in the second outer region, The second outer insulating portion is composed of the second peripheral portion, The inner insulating member is arranged between a pair of bipolar electrodes adjacent to each other in the stacking direction and includes an inner separator having a thickness smaller than the thickness of the first separator. The inner separator comprises an inner intervening portion interposed between the positive electrode active material layer and the negative electrode active material layer in the bipolar electrode, It has an inner peripheral portion that is connected to the inner intervening portion and is located in the inner region, The energy storage module according to claim 1, wherein the inner insulating portion is composed of the inner peripheral portion.

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