Power storage device and vehicle

Abstract

To suppress an excessive temperature rise of a power storage device by enabling discharge of the power storage device before a short circuit occurs inside a stacked electrode assembly when large force is applied to the power storage device from outside.SOLUTION: A power storage device 1 includes a stacked electrode assembly 10 and a seal member 20. An electrode plate 11 (bipolar electrode) having a positive electrode layer 13 and a negative electrode layer 14 is stacked between a positive-electrode termination electrode 16 and a negative-electrode termination electrode 17 with a separator 15 interposed therebetween, and the stacked electrode assembly 10 is formed. An uncoated portion (current collector 12d) of the negative-electrode termination electrode 17 and an uncoated portion (current collector 12a, 12b) of the electrode plate 11 extend in a stacking direction of the stacked electrode assembly 10 together with adjacent separators 15a, 15b, 15c, and are folded so as to be stacked on the positive-electrode termination electrode 16 through the separators 15a, 15b, 15c, thereby forming a crushing-time discharging portion ES.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a power storage device and a vehicle. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2023-152023 (Patent Document 1) discloses an electricity storage device including a bipolar electrode in which active material layers are provided on one surface (first surface) and the other surface (second surface) of a current collector. In Patent Document 1, a bipolar battery is constructed by a laminated electrode body in which bipolar electrodes are stacked with separators interposed therebetween. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-152023 Summary of the Invention [Problem to be solved by the invention]

[0004] When a large external force is applied to the electricity storage device and the separator of the stacked electrode assembly breaks, a short circuit occurs inside the stacked electrode assembly, generating heat and possibly causing an excessive rise in the temperature of the electricity storage device.

[0005] The object of the present disclosure is to suppress excessive temperature rise in an energy storage device by enabling the energy storage device to discharge before a short circuit occurs inside the stacked electrode body when a large external force is applied to the energy storage device. [Means for solving the problem]

[0006] The power storage device of the present disclosure includes a positive electrode terminal electrode having a positive electrode active material layer formed on one side of a current collector and an uncoated portion where the positive electrode active material layer is not formed, a negative electrode terminal electrode having a negative electrode active material layer formed on one side of a current collector and an uncoated portion where the negative electrode active material layer is not formed, and a laminated electrode body in which a bipolar electrode is laminated between the positive electrode terminal electrode and the negative electrode terminal electrode with a separator interposed therebetween. The bipolar electrode has a positive electrode active material layer and a negative electrode active material layer formed on one side and the other side of the current collector, respectively, and has an uncoated portion where the positive electrode active material layer and the negative electrode active material layer are not formed. The uncoated portion of one of the positive electrode terminal electrode and the negative electrode terminal electrode extends together with the adjacent separator in the stacking direction of the laminated electrode body and is folded so as to overlap the other of the positive electrode terminal electrode and the negative electrode terminal electrode with the separator interposed therebetween. The uncoated portion of the other of the positive and negative terminal electrodes and the uncoated portion of the bipolar electrode extend in the stacking direction of the stacked electrode body together with the adjacent separator, and are folded so as to be stacked on one of the positive and negative terminal electrodes with the separator interposed therebetween.

[0007] According to this configuration, a bipolar battery is formed by a laminated electrode assembly in which a bipolar electrode is laminated between a positive terminal electrode and a negative terminal electrode with a separator interposed therebetween. The bipolar electrode, positive terminal electrode, and negative terminal electrode have uncoated portions in which a positive electrode active material layer and a negative electrode active material layer are not formed. The uncoated portion of one of the positive terminal electrode and the negative terminal electrode extends in the stacking direction of the laminated electrode assembly together with the adjacent separator and is folded so as to overlap the other of the positive terminal electrode and the negative terminal electrode with the separator interposed therebetween. The uncoated portion of the other of the positive terminal electrode and the negative terminal electrode and the uncoated portion of the bipolar electrode extend in the stacking direction of the laminated electrode assembly together with the adjacent separator and are folded so as to overlap one of the positive terminal electrode and the negative terminal electrode with the separator interposed therebetween.

[0008] If one uncoated portion is a positive electrode terminal electrode, the uncoated portion of the positive electrode terminal electrode is folded to overlap the negative electrode terminal electrode with a separator interposed therebetween, and the uncoated portions of the negative electrode terminal electrode and bipolar electrode are folded to stack with the positive electrode terminal electrode and separator interposed therebetween. In this case, the area where the uncoated portions of the negative electrode terminal electrode and bipolar electrode are folded to stack with the positive electrode terminal electrode and separator interposed therebetween functions as a collapse discharge portion where the negative electrode terminal electrode current collector and the bipolar electrode current collector are stacked with the separator interposed therebetween.

[0009] If one uncoated portion is a negative electrode terminal electrode, the uncoated portion of the negative electrode terminal electrode is folded so as to overlap with the positive electrode terminal electrode with a separator interposed therebetween, and the uncoated portions of the positive electrode terminal electrode and bipolar electrode are folded so as to be stacked with the negative electrode terminal electrode and separator interposed therebetween. In this case, the region where the uncoated portions of the positive electrode terminal electrode and bipolar electrode are folded so as to be stacked with the negative electrode terminal electrode and separator interposed therebetween functions as a collapse discharge portion where the current collector of the positive electrode terminal electrode and the current collector of the bipolar electrode are stacked with the separator interposed therebetween.

[0010] When a large external force is applied to the energy storage device, before the separators inside the stacked electrode body break and cause a short circuit, the separators in the area that functions as a discharge portion in the event of collapse break and cause a short circuit, and discharge occurs outside the stacked electrode body. This reduces the SOC (Sate of Charge) of the stacked electrode body, thereby suppressing excessive temperature rise in the energy storage device.

[0011] Preferably, the thickness of the separator in the area where it is folded to be laminated with one of the positive and negative terminal electrodes may be thinner than the thickness of the area included in the laminated electrode assembly.

[0012] According to this configuration, the thickness of the separator in the region that functions as the discharge section upon collapse is thinner than the thickness of the region included in the stacked electrode body. Therefore, when a large external force is applied to the energy storage device, the separator in the region that functions as the discharge section upon collapse is more likely to break before the separator inside the stacked electrode body breaks, thereby more suitably suppressing excessive temperature rise in the energy storage device.

[0013] A vehicle according to the present disclosure is equipped with the above-described power storage device. The power storage device is mounted on the floor of the vehicle. The power storage device is arranged so that the side of the folded portion of the positive terminal electrode or the negative terminal electrode, where the uncoated portion of the other of the positive terminal electrode and the negative terminal electrode and the uncoated portion of the bipolar electrode are stacked on one of the positive terminal electrode and the negative terminal electrode via a separator, faces the road surface.

[0014] According to this configuration, the vehicle is equipped with the above-mentioned power storage device on the vehicle floor. The side of the power storage device that functions as a collapse discharge portion is positioned facing the road surface. When the vehicle floor is subjected to a large force due to road contact or the like, the separator in the region that functions as a collapse discharge portion is more likely to break before the separator inside the stacked electrode body breaks, more effectively suppressing excessive temperature rise in the power storage device. [Effects of the Invention]

[0015] According to the present disclosure, when a large external force is applied to an energy storage device, it is possible to discharge the energy storage device before a short circuit occurs inside the stacked electrode body, and to suppress excessive temperature rise in the energy storage device. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view of an electricity storage device according to an embodiment of the present invention. [Figure 2] 1 is a schematic partial cross-sectional view of an electricity storage device according to an embodiment of the present invention. [Figure 3] 10A and 10B are diagrams illustrating the function of a collapse discharge section. [Figure 4] 1(A) and 1(B) are diagrams illustrating a battery module in which a power storage device is housed in an exterior body. [Figure 5] FIG. 1 is a diagram showing a bipolar battery module connected in series with a battery module to form a battery pack. [Figure 6] 1A and 1B are diagrams illustrating a battery pack configured from a battery module and a bipolar battery module. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments described below, identical or common parts are designated by the same reference numerals in the drawings, and their description will not be repeated. The drawings are not drawn according to the actual dimensional ratio, and in some cases, the ratio may be changed to clarify the structure in order to facilitate understanding of the structure.

[0018] Fig. 1 is a schematic cross-sectional view of a power storage device according to the present embodiment. Fig. 2 is a schematic partial cross-sectional view of a power storage device according to the present embodiment. Note that Fig. 2 is a view in which a part of Fig. 1 has been removed to facilitate explanation using reference numerals.

[0019] Referring to Fig. 2, the energy storage device 1 includes a laminated electrode body 10 and a sealing member 20. The energy storage device 1 is, for example, a secondary battery such as a lithium-ion battery. The laminated electrode body 10 includes a plurality of electrode plates 11, a plurality of separators 15, a positive terminal electrode 16, and a negative terminal electrode 17. The plurality of electrode plates 11, the positive terminal electrode 16, and the negative terminal electrode 17 are stacked with the separator 15 interposed therebetween. The direction in which the laminated electrode body 10 is stacked is referred to as the stacking direction.

[0020] The separator 15 is formed in a sheet shape. Examples of the separator 15 include a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), and a woven or nonwoven fabric made of polypropylene, methyl cellulose, etc. The separator 15 may be reinforced with a vinylidene fluoride resin compound.

[0021] The plurality of electrode plates 11 are provided between a positive terminal electrode 16 and a negative terminal electrode 17. The electrode plates 11 include a current collector 12, a positive electrode layer 13, and a negative electrode layer 14. The electrode plates 11 are bipolar electrodes.

[0022] Current collector 12 may contain at least one selected from the group consisting of aluminum (Al), stainless steel, nickel (Ni), chromium (Cr), platinum (Pt), niobium (Nb), iron (Fe), titanium (Ti), copper (Cu), and zinc (Zn). Current collector 12 may also be a metal foil whose surface is plated.

[0023] The current collector 12 has a first main surface located on one side in the stacking direction and a second main surface located on the other side in the stacking direction. A negative electrode layer 14 is provided on the first main surface. A positive electrode layer 13 is provided on the second main surface.

[0024] The current collectors 12a and 12b of the electrode plate 11 may have a two-layer structure in which a current collector for the positive electrode layer 13 and a current collector for the negative electrode layer 14 are stacked together. In this case, the current collector for the positive electrode layer 13 may be made of aluminum (Al), and the current collector for the negative electrode layer 14 may be made of nickel (Ni).

[0025] The positive terminal electrode 16 is located on one side in the stacking direction. The positive terminal electrode 16 includes a current collector 12 and a positive electrode layer 13. In the positive terminal electrode 16, the negative electrode layer 14 and the positive electrode layer 13 are not provided on a first main surface located on one side of the current collector 12, and the positive electrode layer 13 is provided on a second main surface located on the other side of the current collector 12.

[0026] The negative electrode terminal electrode 17 is located on the other side in the stacking direction. The negative electrode terminal electrode 17 includes a current collector 12 and a negative electrode layer 14. In the negative electrode terminal electrode 17, the negative electrode layer 14 is provided on a first type surface located on one side of the current collector 12, and neither the negative electrode layer 14 nor the positive electrode layer 13 is provided on a second type surface located on the other side of the current collector 12.

[0027] The positive electrode layer 13 is formed by applying a positive electrode active material to the second main surface. As the positive electrode active material, for example, a material capable of absorbing and releasing charge carriers such as lithium ions can be used. The positive electrode active material may contain olivine-type lithium iron phosphate (LiFePO4). The positive electrode layer 13 corresponds to the "positive electrode active material layer" of the present disclosure.

[0028] The negative electrode layer 14 is formed by applying a negative electrode active material to the first main surface. Examples of the negative electrode active material include lithium, carbon, metal compounds, and elements or compounds thereof that can be alloyed with lithium. The negative electrode layer 14 corresponds to the "negative electrode active material layer" of the present disclosure.

[0029] In each of the multiple electrode plates 11, the negative terminal electrode 17, and the positive terminal electrode 16, the peripheral edge of the current collector 12 is an uncoated area where the positive electrode layer 13 and the negative electrode layer 14 are not provided. The uncoated area is also referred to as an uncoated portion.

[0030] In this embodiment, two electrode plates 11 (bipolar electrodes) are stacked between a positive terminal electrode 16 and a negative terminal electrode 17 with a separator 15 interposed therebetween. The laminated electrode assembly 10 includes a "first battery cell C1 composed of a negative terminal electrode 17 (current collector 12d, negative electrode layer 14d), a current collector 12a and a positive electrode layer 13a of the electrode plate 11 (bipolar electrode), and a separator 15a," a "second battery cell C2 composed of a current collector 12a and a negative electrode layer 14a of the electrode plate 11, a current collector 12b and a positive electrode layer 13b of the electrode plate 11, and a separator 15b," and a "third battery cell C3 composed of a positive terminal electrode 16 (current collector 12c, positive electrode layer 13c), a current collector 12b and a negative electrode layer 14b of the electrode plate 11 (bipolar electrode), and a separator 15c." The number of stacked electrode plates 11 may be three or more.

[0031] An extension extending in the stacking direction of the laminated electrode assembly 10 is formed on the left side of the uncoated portion of the current collector 12c of the positive terminal electrode 16 and the adjacent separator 15c in Fig. 1, and this extension is folded so as to overlap the current collector 12d of the negative terminal electrode 17. As a result, the current collector 12c of the positive terminal electrode 16 overlaps the current collector 12d of the negative terminal electrode 17 with the adjacent separator 15c interposed therebetween.

[0032] An extension extending in the stacking direction of the laminated electrode body 10 is formed on the right side in Fig. 1 in the uncoated portion of the current collector 12b of the electrode plate 11 adjacent to the positive terminal electrode 16 and in the adjacent separator 15c, and this extension is folded so as to overlap the current collector 12c of the positive terminal electrode 16. As a result, the current collector 12b of the electrode plate 11 overlaps the current collector 12c of the positive terminal electrode with the adjacent separator 15c interposed therebetween.

[0033] An extension portion extending in the stacking direction of the laminated electrode body 10 is formed on the right side in Fig. 1 in the uncoated portion of the current collector 12a of the electrode plate 11 adjacent to the negative terminal electrode 17 and the adjacent separator 15b, and this extension portion is folded so as to overlap the current collector 12b of the electrode plate 11. As a result, the current collector 12a of the electrode plate 11 overlaps the current collector 12b with the adjacent separator 15b interposed therebetween.

[0034] An extension extending in the stacking direction of the laminated electrode assembly 10 is formed on the right side in Fig. 1 in the uncoated portion of the current collector 12d of the negative terminal electrode 17 and the adjacent separator 15a, and this extension is folded so as to overlap the current collector 12a of the electrode plate 11. As a result, the current collector 12d of the negative terminal electrode 17 overlaps the current collector 12a of the electrode plate 11 with the adjacent separator 15a interposed therebetween.

[0035] In this way, the uncoated portions of the negative electrode terminal electrode 17 and the electrode plate 11 extend in the stacking direction of the laminated electrode body 10 together with the adjacent separator 15, and are folded so as to be stacked on the positive electrode terminal electrode 16 with the separator 15 interposed therebetween. The region where the uncoated portions of the negative electrode terminal electrode 17 and the electrode plate 11 are folded so as to be stacked on the positive electrode terminal electrode 16 with the separator 15 interposed therebetween is also referred to as the collapse discharge portion ES.

[0036] The sealing member 20 is provided to seal the periphery of the laminated electrode body 10 and the extensions of the current collectors 12 and separators 15 that extend in the stacking direction. The sealing member 20 seals the internal spaces formed between adjacent electrode plates 11, between the positive terminal electrode 16 and the electrode plate 11, and between the negative terminal electrode 17 and the electrode plate 11. An electrolyte solution is poured into these internal spaces. The sealing member 20 is formed by curing a resin material such as a hot melt material, a thermoplastic resin, a thermosetting resin, or a photocurable resin.

[0037] In the energy storage device 1 configured in this manner, the current collector 12c of the positive terminal electrode 16, which overlaps the current collector 12d with the separator 15c interposed therebetween, functions as a positive terminal region. Also, the current collector 12d of the negative terminal electrode 17, which overlaps the current collector 12a with the separator 15a interposed therebetween, functions as a negative terminal region.

[0038] If a large external force is applied to the electricity storage device 1 and the separator 15 of the laminated electrode body 10 breaks (breaks), a short circuit occurs inside the laminated electrode body 10, generating heat and possibly causing the temperature of the electricity storage device 1 to rise excessively.

[0039] In this embodiment, by forming the collapse discharge portion ES, when a large external force is applied to the energy storage device 1, the energy storage device 1 can discharge before a short circuit occurs inside the laminated electrode body 10, thereby suppressing excessive temperature rise in the energy storage device 1. FIG. 3 is a diagram illustrating the function of the collapse discharge portion ES. In FIG. 3, an external force F presses a round bar (cylinder) B against the collapse discharge portion ES of the energy storage device 1. The collapse discharge portion ES is a region where the negative electrode terminal electrode 17 and the uncoated portion of the electrode plate 11 are folded so that they are stacked on the positive electrode terminal electrode 16 with the separator 15 interposed therebetween. Therefore, as the round bar B advances due to the external force F, the separator 15 located at the collapse discharge portion ES breaks and shorts out before the separator 15 inside the laminated electrode body 10 breaks and shorts out, and discharge occurs outside the laminated electrode body 10.

[0040] For example, as rod B advances due to external force F, separator 15a breaks at the collapse discharge point ES, causing a short circuit between current collector 12d and current collector 12a, and the first battery cell C1 is forcibly discharged outside the laminated electrode body 10. This reduces the SOC of the first battery cell C1. As rod B advances, separator 15b breaks at the collapse discharge point ES, causing a short circuit between current collector 12a and current collector 12b, and the second battery cell C2 is forcibly discharged outside the laminated electrode body 10. As rod B further advances, separator 15c breaks at the collapse discharge point ES, causing a short circuit between current collector 12b and current collector 12c, and the third battery cell C3 is forcibly discharged outside the laminated electrode body 10.

[0041] In this way, when a large external force is applied to the energy storage device 1, before the separators 15 inside the laminated electrode body 10 break and cause a short circuit, the separators 15 in the region of the collapse discharge part ES break and cause a short circuit, and discharge occurs outside the laminated electrode body 10. This reduces the SOC of the laminated electrode body 10, making it possible to suppress excessive temperature rise in the energy storage device 1.

[0042] 1, in the present embodiment, the thickness t2 of the separator 15 in the region of the collapse discharge portion ES is made thinner than the thickness t1 of the region included in the laminated electrode body 10. Because the thickness t2 is made thinner than the thickness t1, when a large external force is applied to the energy storage device 1, the separator 15 in the region of the collapse discharge portion ES is more likely to break before the separator 15 inside the laminated electrode body 10 breaks and a short circuit occurs, and discharge outside the laminated electrode body 10 can be performed more reliably.

[0043] FIG. 4 is a diagram illustrating a battery module 100 in which an energy storage device 1 is housed in an exterior housing 40. The battery module 100 is formed by housing the energy storage device 1 in the exterior housing 40. FIG. 4(A) is a perspective view of the battery module 100, and FIG. 4(B) is a cross-sectional view taken along line BB shown in FIG. 4(A). The exterior housing 40 includes an A exterior housing 41 and a B exterior housing 42. The A exterior housing 41 and the B exterior housing 42 are joined at their respective peripheral edges to seal the energy storage device 1 inside. The A exterior housing 41 is disposed on the current collector 12d of the negative terminal electrode 17, which is located on one side in the stacking direction (the collapse discharge portion ES side). The B exterior housing 42 is disposed on the current collector 12c of the positive terminal electrode 16, which is located on the other side in the stacking direction.

[0044] The A exterior package 41 includes a first conductive plate 18, a resin layer 50, and a first sheet member 31. The B exterior package 42 includes a second conductive plate 19, a resin layer 50, and a second sheet member 32.

[0045] The first conductive plate 18 and the second conductive plate 19 are disposed to sandwich the energy storage device 1 in the stacking direction. The first conductive plate 18 is disposed on the current collector 12d of the negative terminal electrode 17. The first conductive plate 18 is disposed in contact with the current collector 12d, thereby electrically connected to the negative terminal electrode 17. The first conductive plate 18 is electrically connected to the negative terminal electrode 17, thereby functioning as the negative terminal of the battery module 100. The second conductive plate 19 is disposed on the current collector 12c of the positive terminal electrode 16. The second conductive plate 19 is disposed in contact with the current collector 12c, thereby electrically connected to the positive terminal electrode 16. The second conductive plate 19 is electrically connected to the positive terminal electrode 16, thereby functioning as the positive terminal of the battery module 100. In the battery module 100, current can be extracted from the storage device 1 housed inside via the first conductive plate 18, which functions as a negative terminal, and the second conductive plate 19, which functions as a positive terminal, without using tabs to extract the current to the outside.

[0046] First sheet member 31 forms the peripheral portion of A exterior body 41. First sheet member 31 is joined to the peripheral edge of first conductive plate 18. In the present embodiment, first sheet member 31 is joined to first conductive plate 18 with resin layer 50 interposed between first sheet member 31 and the peripheral edge of first conductive plate 18.

[0047] The second sheet member 32 forms the peripheral portion of the B exterior package 42. The second sheet member 32 is joined to the peripheral edge of the second conductive plate 19. In the present embodiment, the second sheet member 32 is joined to the second conductive plate 19 with a resin layer 50 interposed between the second sheet member 32 and the peripheral edge of the second conductive plate 19.

[0048] The peripheries of first conductive plate 18 and second conductive plate 19 are located on sealing member 20. Resin layer 50 may be made of an insulating resin material. Resin layer 50 may be made of a resin material that can be welded to first conductive plate 18 or second conductive plate 19. Resin layer 50 may be made of a heat-sealable resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

[0049] In this embodiment, the first sheet member 31 and the second sheet member 32 are laminate films. The first sheet member 31 has a first metal layer 310, a first insulating layer 311, and a second insulating layer 312. The first metal layer 310 may be a metal foil such as Al foil, Ni foil, Cu foil, or stainless steel foil. The first insulating layer 311 and the second insulating layer 312 may be made of a heat-sealable resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene. The second insulating layer 312 may be made of a material different from the first insulating layer 311. The second insulating layer 312 may be made of a single layer of polyethylene terephthalate or nylon, or a laminate of these materials. The first insulating layer 311 and the second insulating layer 312 may be made of a single layer or a multilayer structure.

[0050] The second sheet member 32 has a second metal layer 320, a first insulating layer 321, and a second insulating layer 322. The second metal layer 320, the first insulating layer 321, and the second insulating layer 322 may be the same as the first metal layer 310, the first insulating layer 311, and the second insulating layer 312.

[0051] The outer peripheries of the first sheet member 31 of the A exterior body 41 and the second sheet member 32 of the B exterior body 42 are joined by welding. As a result, the first insulating layer 311 of the A exterior body 41 and the first insulating layer 321 of the B exterior body 42 are welded together while facing each other, and the energy storage device 1 is sealed in the A exterior body 41 and the B exterior body 42. A welded portion 70 is formed on the outer periphery where the A exterior body 41 and the B exterior body 42 are welded together.

[0052] FIG. 5 shows a bipolar battery module 100A that is connected in series with the battery module 100 of the present embodiment to form a battery pack. FIG. 5(A) is a perspective view of the bipolar battery module 100A, and FIG. 5(B) is a cross-sectional view taken along line BB in FIG. 5(A). The bipolar battery module 100A essentially has a configuration in which the collapse discharge section ES is omitted from the battery module 100 of FIG. 4. The bipolar battery module 100A includes a power storage unit 1A having a stacked electrode body 10A and a sealing member 20A, and an exterior body 40A that houses the power storage unit 1A.

[0053] The laminated electrode assembly 10A includes multiple electrode plates 11A, multiple separators 15A, a positive terminal electrode 16A, and a negative terminal electrode 17A. The multiple electrode plates 11A, positive terminal electrode 16A, and negative terminal electrode 17A are stacked in the stacking direction with separators 15A interposed between them. The number of electrode plates 11A is arbitrary and may be, for example, 5, 20, or 30.

[0054] Electrode plate 11A is substantially the same as the above-described electrode plate 11, with a positive electrode layer 13A formed on one surface of current collector 12A and a negative electrode layer 14A formed on the other surface of current collector 12A. Current collector 12A, positive electrode layer 13A, and negative electrode layer 14A are substantially the same as the above-described positive electrode layer 13 and negative electrode layer 14, and electrode plate 11A is a bipolar electrode.

[0055] Separator 15A, positive terminal electrode 16A, and negative terminal electrode 17A are substantially identical to separator 15, positive terminal electrode 16, and negative terminal electrode 17 described above.

[0056] In any of the multiple electrode plates 11A, the positive terminal electrode 16A, and the negative terminal electrode 17A, the uncoated portion of the periphery of the current collector 12A does not have an extension portion formed therein that extends in the stacking direction of the stacked electrode body 10. In addition, the separator 15A does not have an extension portion formed therein that extends in the stacking direction of the stacked electrode body 10.

[0057] The sealing member 20A is provided to seal the periphery of the laminated electrode body 10A. The sealing member 20A seals the internal spaces formed between adjacent electrode plates 1A1, between the positive terminal electrode 16A and the electrode plate 11A, and between the negative terminal electrode 17A and the electrode plate 11A. An electrolyte is poured into these internal spaces.

[0058] Exterior body 40A includes exterior bodies 41A and 42A. Exterior body 41A includes a conductive plate 19A, a resin layer 50A, and a sheet member 31A. Exterior body 42A includes a conductive plate 18A, a resin layer 50A, and a sheet member 32A.

[0059] The conductive plate 18A and the conductive plate 19A are arranged to sandwich the laminated electrode body 10A in the stacking direction. The conductive plate 19A is disposed on and in contact with the current collector 12A of the positive terminal electrode 16A, thereby electrically connecting to the positive terminal electrode 16A. The conductive plate 19A functions as the positive terminal of the bipolar battery module 100A. The conductive plate 18A is disposed on and in contact with the current collector 12A of the negative terminal electrode 17A, thereby electrically connecting to the negative terminal electrode 17A. The conductive plate 18A functions as the negative terminal of the bipolar battery module 100A. The other configurations of the exterior body 40A are similar to those of the above-described exterior body 40, and therefore description thereof will be omitted.

[0060] FIG. 6 is a diagram illustrating a battery pack BT composed of a battery module 100 and a bipolar battery module 100A. As shown in FIG. 6(A), the battery module 100 and the bipolar battery module 100A are stacked with a conductive member 200 between the second conductive plate 19 (positive terminal) of the battery module 100 and the conductive plate 18A (negative terminal) of the bipolar battery module 100A. The bipolar battery module 100A is then stacked between the conductive plate 18A (positive terminal) and the conductive plate 19A (negative terminal) with the conductive member 200 interposed therebetween. The number of bipolar battery modules 100A may be any number, such as three or ten. As shown in FIG. 6(A), the battery module 100 and the bipolar battery module 100A are connected in series to form a battery pack, and the battery pack BT is formed by housing the battery pack in a battery case (not shown).

[0061] As shown in FIG. 6(B), the battery pack BT is disposed on the floor 500 of the vehicle V and is mounted on the vehicle V. The battery pack BT is mounted on the floor 500 of the vehicle V so that the first conductive plate 18 of the battery module 100 faces the road surface G (so that the first conductive plate 18 faces vertically downward). As a result, the battery pack BT is mounted on the vehicle V so that the collapse-time discharge portion ES of the power storage device 1 faces the road surface G. Therefore, when the floor 500 of the vehicle V is subjected to a large force due to road surface interference or the like, in the battery module 100, before the separator 15 inside the stacked electrode body 10 breaks and a short circuit occurs, the separator 15 in the region of the collapse-time discharge portion ES breaks and a short circuit occurs, and discharge occurs outside the stacked electrode body 10. As a result, the SOC of the stacked electrode body 10 decreases, and an excessive temperature rise in the battery pack BT (power storage device 1) can be suppressed.

[0062] In the above embodiment, in the energy storage device 1, the uncoated portions of the negative electrode terminal electrode 17 and the electrode plate 11 extend in the stacking direction of the laminated electrode body 10 together with the adjacent separator 15 and are folded so as to be stacked on the positive electrode terminal electrode 16 with the separator 15 interposed therebetween. The region where the uncoated portions of the negative electrode terminal electrode 17 and the electrode plate 11 are folded so as to be stacked on the positive electrode terminal electrode 16 with the separator 15 interposed therebetween is used as the collapse discharge portion ES. However, the uncoated portions of the positive electrode terminal electrode 16 and the electrode plate 11 may also extend in the stacking direction of the laminated electrode body 10 together with the adjacent separator 15 and be folded so as to be stacked on the negative electrode terminal electrode 17 with the separator 15 interposed therebetween. In this case, the region where the uncoated portions of the positive electrode terminal electrode 16 and the electrode plate 11 are folded so as to be stacked on the negative electrode terminal electrode 17 with the separator 15 interposed therebetween functions as the collapse discharge portion ES.

[0063] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0064] 1 Energy storage device, 1A Energy storage body, 10,10A Laminated electrode body, 11,11A Electrode plate, 12,12A Current collector, 13,13A Positive electrode layer, 14,14A Negative electrode layer, 15,15A Separator, 16,16A Positive electrode terminal electrode, 17,17A Negative electrode terminal electrode, 18 First conductive plate, 18A Conductive plate, 19 Second conductive plate, 19A Conductive plate, 20,20A Sealing member, 31 First sheet member, 32 Second sheet member, 40,40A Outer body, 41 A Outer body, 42 B Outer body, 50 Resin layer, 100 Battery module, 100A Bipolar battery module, 200 Conductive member, 500 Floor, BT Battery pack, ES Crush discharge part, V Vehicle.

Claims

1. a positive electrode terminal electrode having the positive electrode active material layer formed on one surface of a current collector and an uncoated portion where the positive electrode active material layer is not formed; a negative electrode terminal electrode having the negative electrode active material layer formed on one surface of a current collector and an uncoated portion where the negative electrode active material layer is not formed; a laminated electrode body in which a bipolar electrode is laminated between the positive terminal electrode and the negative terminal electrode with a separator interposed therebetween; the bipolar electrode has the positive electrode active material layer and the negative electrode active material layer formed on one surface and the other surface of a current collector, respectively, and has an uncoated portion where the positive electrode active material layer and the negative electrode active material layer are not formed, the uncoated portion of one of the positive terminal electrode and the negative terminal electrode extends in the stacking direction of the stacked electrode body together with the adjacent separator, and is folded so as to overlap the other of the positive terminal electrode and the negative terminal electrode with the separator interposed therebetween; the uncoated portion of the other of the positive terminal electrode and the negative terminal electrode and the uncoated portion of the bipolar electrode extend in the stacking direction of the stacked electrode body together with the adjacent separator, and are folded so as to be stacked on one of the positive terminal electrode and the negative terminal electrode with the separator interposed therebetween.

2. The separator is The power storage device according to claim 1 , wherein a thickness of a region folded to be laminated on one of the positive terminal electrode and the negative terminal electrode is thinner than a thickness of a region included in the laminated electrode body.

3. A vehicle equipped with the power storage device according to claim 1 or 2, the power storage device is mounted on a floor of the vehicle, the power storage device is a vehicle, wherein the uncoated portion of the other of the positive terminal electrode and the negative terminal electrode and the uncoated portion of the bipolar electrode are folded so as to be stacked on one of the positive terminal electrode and the negative terminal electrode with the separator interposed between them, and the folded side is arranged so as to face a road surface.

Images