Energy storage device

Abstract

Energy storage device (1) comprising: an energy storage module (4); and a pair of conductive plates (5) arranged in such a way as to sandwich the energy storage module (4), wherein the energy storage module (4) has an electrode laminate (11) comprising a plurality of laminated bipolar electrodes (14) and a pair of terminal electrodes (18, 19) and a sealing body (12) designed to seal the electrode laminate (11), wherein the pair of connecting electrodes (18, 19) is arranged at laminate ends of the electrode laminate (11), and the connecting electrodes (18, 19) provided as a pair each have an electrode plate (15) and an active material layer (16, 17) which is provided on a surface of the electrode plate (15) which is opposite an inside of the electrode laminate (11), wherein the sealing body (12) has a pair of plastic sections (21, 22) which are provided on edge sections (15c) of the pair of connection electrodes (18, 19), wherein at least one conductive plate (5) from the pair of conductive plates (5) is arranged such that it faces a corresponding terminal electrode (18, 19) from the pair of terminal electrodes (18, 19) in a lamination direction (D) of the electrode laminate (11) and overlaps with a corresponding plastic section (21, 22) from the pair of plastic sections (21, 22) when viewed in the lamination direction (D), wherein the at least one conductive plate (5) is in direct contact with the electrode plate (15) of the corresponding connecting electrodes (18, 19) on a surface that faces away from the electrode laminate (11), wherein the active material layer (16, 17) of each terminal electrode (18, 19) is provided only on the surface of the electrode plate (15) which faces the inside of the electrode laminate (11), and wherein the at least one conductive plate (5) has a plurality of flow paths (5a) extending in a direction perpendicular to the lamination direction (D) and are arranged such that a coolant circulates through them.

Description

Technical field

[0001] One aspect of the present invention relates to an energy storage device. Background of the state of the art

[0002] An energy storage device of the prior art is known which has a bipolar energy storage module comprising a bipolar electrode in which a positive electrode is formed on one surface of an electrode plate and a negative electrode is formed on the other surface (see patent document 1). Such an energy storage module comprises an electrode laminate formed by laminating a plurality of bipolar electrodes. A sealing element is provided on the circumference of the electrode laminate, which is designed to seal sections between the bipolar electrodes that are adjacent to each other in the lamination direction. An electrolytic solution is contained in the spaces formed by the sealing element between the bipolar electrodes. List of state-of-the-art patent documents Patent document 1: Unexamined Japanese patent publication JP 2011-204386 A Patent document 2: EP 1 428 272 B1 Patent document 3: DE 11 2017 005 247 T5

[0003] EP 1 428 272 B1 discloses an energy storage device comprising: an energy storage module and a pair of conductive plates arranged in such a way as to sandwich the energy storage module, wherein the energy storage module has an electrode laminate comprising a plurality of laminated bipolar electrodes and a pair of terminal electrodes, and has a sealing body designed to seal the electrode laminate, wherein the pair of connecting electrodes is arranged at laminate ends of the electrode laminate, and the connecting electrodes provided as a pair each have an electrode plate and an active material layer which is provided on a surface of the electrode plate which is opposite an inside of the electrode laminate, wherein the sealing body has a pair of plastic sections which are provided at edge sections of the pair of connecting electrodes, wherein at least one conductive plate from the pair of conductive plates is arranged such that it faces a corresponding terminal electrode from the pair of terminal electrodes in a lamination direction of the electrode laminate and overlaps with a corresponding plastic section from the pair of plastic sections when viewed in the lamination direction.

[0004] DE 11 2017 005 247 T5 discloses an electricity storage device comprising: an energy storage module; and a pair of conductive plates arranged in such a way as to sandwich the energy storage module, wherein the energy storage module has an electrode laminate comprising a plurality of laminated bipolar electrodes and a pair of terminal electrodes, and has a sealing body designed to seal the electrode laminate, wherein the pair of connecting electrodes is arranged at laminate ends of the electrode laminate, and the connecting electrodes provided as a pair each have an electrode plate and an active material layer which is provided on a surface of the electrode plate which is opposite an inside of the electrode laminate, wherein the sealing body has a pair of plastic sections which are provided at edge sections of the pair of connecting electrodes, wherein at least one conductive plate from the pair of conductive plates is arranged such that it faces a corresponding terminal electrode from the pair of terminal electrodes in a lamination direction of the electrode laminate and overlaps with a corresponding plastic section from the pair of plastic sections when viewed in the lamination direction. Summary of the invention: Technical problem

[0005] In the energy storage module described above, there is a case where the internal pressure between the bipolar electrodes increases depending on the operating conditions or similar factors. If the internal pressure increases, it is conceivable that an electrode positioned at one end of the electrode laminate (hereinafter referred to as the terminal electrode) could deform significantly towards the outside of the electrode laminate along the lamination direction.

[0006] If the terminal electrode deforms excessively, the stress applied to the sealant increases, and there is a risk of the sealant breaking. Another problem is that a gap can form between the sealant and the terminal electrode. Breakage of the sealant can cause leakage of the electrolytic solution to the outside of the electrode laminate. The formation of the gap between the sealant and the terminal electrode can also cause leakage of the electrolytic solution to the outside of the electrode laminate.

[0007] One aspect of the present invention is intended to solve the problem described above, and the objective is to create an energy storage device capable of minimizing the excessive deformation of a terminal electrode even when the internal pressure increases. Solution to the problem

[0008] This problem is solved by an energy storage device having the features of claim 1. Advantageous further developments are the subject of the dependent claims.

[0009] In this energy storage device, at least one conductive plate is arranged so that it overlaps a corresponding plastic section. Therefore, even if the internal pressure of the energy storage module increases, excessive deformation of the terminal electrode can be suppressed (prevented) by the conductive plate.

[0010] The conductive plate can be positioned so that it overlaps a corresponding plastic section over the entire circumference of the edge section of the relevant terminal electrode, viewed in the lamination direction. In this case, it is possible to further suppress excessive deformation of the terminal electrode with the conductive plate.

[0011] The length of an edge section of the electrode laminate in the lamination direction can be shorter than the length of a middle section of the electrode laminate in the lamination direction. In this case, even if the plastic section is located on the surface of the electrode plate of the terminal electrode, facing the outside of the electrode laminate, the conductive plate can still be brought into contact with the electrode plate.

[0012] One conductive plate can be in contact with the corresponding plastic section. In this case, excessive deformation of the connecting electrode can be further suppressed by the conductive plate.

[0013] Each of the pair of conductive plates can be arranged so that it faces each of the pair of connecting electrodes in the lamination direction of the electrode laminate and overlaps each of the pair of plastic sections, also in the lamination direction. In this case, excessive deformation of the pair of connecting electrodes by the pair of conductive plates can be avoided (suppressed). Advantageous effects of the invention

[0014] According to one aspect of the present invention, excessive deformation of the terminal electrode can be avoided even when the internal pressure increases. Brief description of the drawings Fig. Figure 1 shows a schematic sectional view of an energy storage device according to an exemplary embodiment. Fig. Figure 2 shows a schematic sectional view of an energy storage module according to the exemplary embodiment. Fig. Figure 3 shows an enlarged cross-sectional view of a substantial section, showing an external appearance of a negative electrode terminal electrode when the internal pressure of an energy storage module in an energy storage device according to a reference example increases. Fig. Figure 4 shows an enlarged cross-sectional view of a substantial section, showing an external appearance of a positive electrode terminal electrode when the internal pressure of the energy storage module in the energy storage device increases according to the reference example. Description of the exemplary implementations

[0015] An exemplary embodiment is described in detail below with reference to the attached drawings.

[0016] The description uses the same reference symbols for identical elements with the same function, and these elements are not described repeatedly. Structure of the energy storage device

[0017] Fig. Figure 1 shows a schematic sectional view of an energy storage device according to an exemplary embodiment. An energy storage device 1 shown in the same drawing is used as a battery for a variety of vehicles, such as a forklift, a hybrid vehicle, an electric vehicle, and the like. The energy storage device 1 comprises an energy storage module laminate 2 with a plurality of laminated energy storage modules 4 and a retaining element 3, which is designed to apply a holding load to the energy storage module laminate 2 in a lamination direction.

[0018] The energy storage module laminate 2 comprises, for example, a plurality of (in the present embodiment, three) energy storage modules 4 and a plurality of (in the present embodiment, four) conductive plates 5. The energy storage module 4 is, for example, a bipolar battery having a bipolar electrode 14 as described below. The energy storage module 4 has a rectangular shape when viewed in the lamination direction. The energy storage module 4 is, for example, at least either a secondary battery, such as a nickel-metal hydride secondary battery or a lithium-ion secondary battery, or an electrical double-layer capacitor. In the following description, a nickel-metal hydride secondary battery is used as an example.

[0019] In the energy storage module laminate 2, the energy storage modules 4 and 4, which are adjacent to each other in the lamination direction, are electrically connected to each other by the conductive plate 5. The conductive plates 5 are arranged between the energy storage modules 4 and 4, which are adjacent to each other in the lamination direction, and on the outside of the energy storage modules 4 that are positioned at the laminators. It can be said that each energy storage module 4 is sandwiched between a pair of conductive plates 5. A positive electrode terminal 6 is connected to a conductive plate 5 that is arranged on the outside of the energy storage module 4 that is positioned at one end of the laminate. A negative electrode terminal 7 is connected to the other conductive plate 5 that is arranged on the outside of the energy storage module 4 that is positioned at the other end of the laminate.The positive electrode terminal 6 and the negative electrode terminal 7 are, for example, drawn from the edge sections of the conductive plates 5 in a direction that intersects the lamination direction. The energy storage device 1 is charged and discharged via the positive electrode terminal 6 and the negative electrode terminal 7.

[0020] Each of the conductive plates 5 has a plurality of flow paths 5a through which a coolant, such as air, circulates. Each flow path 5a extends parallel to, for example, a direction perpendicular to the lamination direction and the drawing direction of the positive electrode terminal 6 and the negative electrode terminal 7, respectively. When the coolant circulates through these flow paths 5a, the conductive plate 5 functions not only as a connecting element, designed to electrically connect the energy storage modules 4 and 4, but also as a heat dissipation plate, designed to dissipate the heat generated by the energy storage module 4. The area of ​​the conductive plate 5, considered in the lamination direction, is smaller than, for example, the area of ​​the energy storage module 4.

[0021] The retaining element 3 comprises a pair of end plates 8 and 8, configured to position the energy storage module laminate 2 between them in the lamination direction, and fastening screws 9 and nuts 10, configured to secure the end plates 8 and 8. The end plate 8 is a rectangular metal plate with an area slightly larger than the area of ​​the energy storage module 4 and the area of ​​the conductive plate 5, both considered in the lamination direction. An electrically insulating film F is provided on the inner surface (the surface facing the energy storage module laminate 2) of the end plate 8, and the end plate 8 and the conductive plate 5 are electrically insulated.

[0022] An insertion hole 8a is provided on an edge section of the end plate 8 at a position on the outside of the energy storage module laminate 2. The fastening screw 9 passes through the insertion hole 8a of one end plate 8 to the insertion hole 8a of the other end plate 8, and the nut 10 is screwed into the distal end section of the fastening screw 9, which projects from the insertion hole 8a of the other end plate 8. As a result, the energy storage modules 4 and the conductive plates 5 are arranged by the end plates 8 and 8 such that a single unit is formed as the energy storage module laminate 2, and a holding load is applied to the energy storage module laminate 2 in the lamination direction. Structure of the energy storage module

[0023] The structure of energy storage module 4 is described below. Fig. Figure 2 shows a schematic sectional view of the energy storage module according to the exemplary embodiment. As shown in the drawing, the energy storage module 4 has an electrode laminate 11 and a plastic sealing body 12, which is designed to seal the electrode laminate 11.

[0024] The electrode laminate 11 is structured such that a plurality of bipolar electrodes 14, a negative electrode terminal 18, and a positive electrode terminal 19 are laminated through separators 13. That is, the electrode laminate 11 comprises the plurality of bipolar electrodes 14, the negative electrode terminal 18, and the positive electrode terminal 19, which are laminated through the separators 13. In the present embodiment, the lamination direction D of the electrode laminate 11 and the lamination direction of the energy storage module laminate 2 coincide. The electrode laminate 11 has side surfaces 11a that extend in the lamination direction D. The bipolar electrode 14 has an electrode plate 15, a positive electrode 16 which is provided on a first surface 15a of the electrode plate 15, and a negative electrode 17 which is provided on a second surface 15b of the electrode plate 15.The positive electrode 16 is a positive electrode active material layer formed by the application of a positive electrode active material. The negative electrode 17 is a negative electrode active material layer formed by the application of a negative electrode active material. In the electrode laminate 11, the positive electrode 16 in one bipolar electrode 14 faces the negative electrode 17 in the other bipolar electrode 14, which is adjacent to the first bipolar electrode in the lamination direction D, with the separator 13 located between them.

[0025] The negative electrode connection electrode 18 is arranged at one end of the electrode laminate 11. The negative electrode connection electrode 18 comprises the electrode plate 15 and the negative electrode 17, which is provided on the second surface 15b of the electrode plate 15. The first surface 15a of the electrode plate 15 in the negative electrode connection electrode 18 is an outer surface facing the outside of the electrode laminate 11, and the second surface 15b is an inner surface facing the inside of the electrode laminate 11. The negative electrode 17 in the negative electrode connection electrode 18 is separated from the positive electrode 16 in the bipolar electrode 14 by the separator 13.

[0026] The positive electrode connection electrode 19 is arranged at the other end of the electrode laminate 11. The positive electrode connection electrode 19 comprises the electrode plate 15 and the positive electrode 16, which is provided on the first surface 15a of the electrode plate 15. The first surface 15a of the electrode plate 15 in the positive electrode connection electrode 19 is an inner surface facing the inside of the electrode laminate 11, and the second surface 15b is an outer surface facing the outside of the electrode laminate 11. The positive electrode 16 in the positive electrode connection electrode 19 is separated from the negative electrode 17 in the bipolar electrode 14 by the separator 13.

[0027] The electrode plate 15 is formed, for example, from a metal foil made of nickel or a nickel-plated steel plate and has a rectangular shape. An edge section 15c of the electrode plate 15 is an area (uncoated area) in which neither the positive electrode active material nor the negative electrode active material is provided on the first surface 15a and the second surface 15b. A central section 15d, surrounded by the edge sections 15c of the electrode plate 15, is an area (coated area) in which at least either the positive electrode active material or the negative electrode active material is provided on at least either the first surface 15a and / or the second surface 15b. The central section 15d forms an electrode section in the bipolar electrode 14, the negative electrode terminal electrode 18, and the positive electrode terminal electrode 19, respectively.

[0028] Examples of the positive electrode active material forming the positive electrode 16 include nickel hydroxide. Examples of the negative electrode active material forming the negative electrode 17 include a hydrogen storage alloy. In the present embodiment, the area where the negative electrode 17 is formed on the second surface 15b of the electrode plate 15 is slightly larger than the area where the positive electrode 16 is formed on the first surface 15a of the electrode plate 15. Therefore, the size of the central section 15d of the bipolar electrode 14 is the size of the area where the negative electrode 17 is formed on the second surface 15b of the electrode plate 15.

[0029] Separator 13 is, for example, in a sheet form. Examples of separator 13 include a porous film made of a polyolefin-based plastic, such as polyethylene (PE) or polypropylene (PP); a woven or nonwoven fabric made of polypropylene, polyethylene terephthalate (PET), methylcellulose, or the like; etc. Separator 13 can be a separator reinforced with a vinylidene fluoride plastic compound. Separator 13 is not limited to the sheet form, and a bag-shaped separator can also be used.

[0030] In the electrode laminate 11, the sealing element 12 seals the sections between the bipolar electrodes 14 and 14, which are adjacent to each other in the lamination direction D, the section between the negative electrode terminal electrode 18 and the bipolar electrode 14, which are adjacent to each other in the lamination direction D, and the section between the positive electrode terminal electrode 19 and the bipolar electrode 14, which are adjacent to each other in the lamination direction D. The sealing element 12 is, for example, made of an insulating plastic in a rectangular cylindrical shape. The sealing element 12 is designed such that it holds the edge sections 15c of the electrode plates 15 against the side surfaces 11a of the electrode laminate 11, which extend in the lamination direction D, and surrounds the side surfaces 11a.

[0031] The sealing body 12 comprises first plastic sections 21 and second plastic sections 22. The first plastic sections 21 are provided at the edge sections 15c of the respective electrode plates 15 in the bipolar electrodes 14, the negative electrode terminal electrode 18, and the positive electrode terminal electrode 19. The second plastic sections 22 are designed to surround all of the first plastic sections 21 from the outside. The first plastic section 21 is formed, for example, by injection molding a plastic and extends continuously over all sides of the electrode plate 15 at the edge sections 15c (unapplied area) on the side of the first surface 15a of the electrode plate 15. The first plastic section 21 is firmly (strongly) bonded to the edge section 15c, for example, by welding using ultrasonic waves or heat.The first plastic section 21 seals the electrode laminate 11 and also acts as a spacer between the electrode plates 15 and 15, which are adjacent to each other in the lamination direction D.

[0032] The first plastic section 21 has a first section 21a, which overlaps the edge section 15c of the electrode plate 15 when viewed in the lamination direction D, and a second section 21b, which forms an overhang on the outside of the edge of the electrode plate 15. The length of the second section 21b in the lamination direction D is longer than the length of the first section 21a in the lamination direction D. Therefore, the first plastic section 21 has a ramp 21c between the first section 21a and the second section 21b. The ramp 21c covers the entire end face of the electrode plate 15 (i.e., part of the side face 11a). The first plastic section 21 is spaced (removed, turned away) from the positive electrode 16 and the negative electrode 17 in a direction perpendicular to the lamination direction D.

[0033] In the connection between the first plastic section 21 and the electrode plate 15, the contact surface of the electrode plate 15 with the first plastic section 21 is a roughened plate surface provided with a plurality of small projections. In the present embodiment, the entire surface of the first surface 15a of the electrode plate 15, which is provided with the positive electrode 16, is a roughened plate surface. The small projection is, for example, a protruding metallic deposit (including an added substance) formed by electroplating performed on the electrode plate 15.On the roughened plate surface, the plastic material forming the first plastic section 21 enters the gaps (spaces) between the small protrusions, creating an anchoring effect and improving the bond strength and liquid tightness between the electrode plate 15 and the first plastic section 21.

[0034] The second plastic section 22 surrounds the first plastic section 21 from the outside and forms an outer wall (housing) of the energy storage module 4. The second plastic section 22 is formed, for example, by injection molding a plastic and extends over the entire length of the electrode laminate 11 in the lamination direction D. The second plastic section 22 has a side surface section 22a and a pair of overhang sections 22b. The side surface section 22a is provided along the side surface 11a of the electrode laminate 11 and connects the plurality of first plastic sections 21, which are arranged in the lamination direction D, to one another. The overhang section 22b forms an overhang at the end surface of the second section 21b of the first plastic section 21 in the lamination direction D from an end section 22c of the side surface section 22a in the lamination direction D.The overhang section 22b extends continuously across all sides of the electrode plate 15. The second plastic section 22 is welded to the outer surface of the first plastic section 21, for example, by heat generated during injection molding.

[0035] The plastic forming the first plastic section 21 and the plastic forming the second plastic section 22 are compatible plastics, for example, the same plastic. Examples of the plastic forming the first plastic section 21 and the second sealing body include polypropylene (PP), polyphenylene sulfide (PPS), modified polyphenylene ether (modified PPE), and the like.

[0036] An interior space V, defined by the distance between the first plastic sections 21 and 21 in the lamination direction D, is formed between the electrode plates 15 and 15. An electrolytic solution E, consisting, for example, of an alkaline solution such as an aqueous potassium hydroxide solution, is contained within the interior space V. The separators 13, the positive electrodes 16, and the negative electrodes 17 are impregnated with the electrolytic solution E. A plurality of communication holes (not shown) are provided in the sealing body 12, communicating with each interior space V. The communication hole functions as a liquid injection port for injecting the electrolytic solution E into each interior space V and also serves—after the injection of the electrolytic solution E—as a connection port for a pressure control valve (not shown).

[0037] The positional relationship between the conductive plate 5 and the energy storage module 4 is described below. As described above, the energy storage module 4 is sandwiched between the pair of conductive plates 5. A first conductive plate 5 is positioned such that it faces the first surface 15a in the negative electrode connection electrode 18 in the lamination direction D and overlaps with the first plastic section 21, which is provided at the edge section 15c in the negative electrode connection electrode 18, when viewed in the lamination direction D (hereinafter referred to as the first plastic section 21 in the negative electrode connection electrode 18). More precisely, the outer edge section of the first conductive plate 5 overlaps with the inner edge section of the first section 21a of the first plastic section 21 in the negative electrode connection electrode 18, when viewed in the lamination direction D.The first conductive plate 5 is arranged such that it overlaps with the first plastic section 21 in the negative electrode connection electrode 18 over the entire circumference of the edge section 15c in the negative electrode connection electrode 18 when viewed in the lamination direction D.

[0038] The second conductive plate 5 is arranged such that it faces the second surface 15b in the positive electrode connection electrode 19 in the lamination direction D and overlaps with the first plastic section 21, which is provided at the edge section 15c in the positive electrode connection electrode 19, when viewed in the lamination direction D (hereinafter referred to as the first plastic section 21 in the positive electrode connection electrode 19). More precisely, the outer edge section of the second conductive plate 5 overlaps with the inner edge section of the first section 21a of the first plastic section 21 in the positive electrode connection electrode 19 when viewed in the lamination direction D.The first conductive plate 5 is arranged such that it overlaps with the first plastic section 21 in the positive electrode connection electrode 19 over the entire circumference of the edge section 15c in the positive electrode connection electrode 19 when viewed in the lamination direction D.

[0039] In the energy storage module 4, the electrode laminate 11 forms a shape that swells more in a central section 11c in the lamination direction D than at an edge section 11b. That is, the length L1 of the edge section 11b of the electrode laminate 11 in the lamination direction D is shorter than the length L2 of the central section 11c of the electrode laminate 11 in the lamination direction D. Therefore, the central section 15d in the negative electrode terminal electrode 18 on the side of the first surface 15a is in contact with the first conductive plate 5 adjacent to the energy storage module 4 in the lamination direction D. The central section 15d in the positive electrode terminal electrode 19 on the side of the second surface 15b is in contact with the second conductive plate 5 adjacent to the energy storage module 4 in the lamination direction D.

[0040] The edge section 11b of the electrode laminate 11 includes the edge section 15c of each electrode plate 15. The middle section 11c of the electrode laminate 11 includes the middle section 15d of each electrode plate 15 and forms an electrode section of the electrode laminate 11. The shape of the electrode laminate 11, in which the length L1 is shorter than the length L2, is obtained by adjusting the thicknesses (lengths in the lamination direction D) of the first plastic section 21, the electrode plate 15, the positive electrode 16, the negative electrode 17, and the separator 13. More precisely, the thicknesses are adjusted such that the thickness of the second section 21b of the first plastic section 21 is less than the sum of the thicknesses of the electrode plate 15, the positive electrode 16, the negative electrode 17, and the separator 13.

[0041] The swelling of the central section 15d with respect to the edge section 15c in the negative electrode terminal electrode 18 (the separation distance in the lamination direction D between the edge section 15c on the side of the first surface 15a and the central section 15d on the side of the first surface 15a in the negative electrode terminal electrode 18) is equal to or greater than the thickness (the length in the lamination direction D) of the first section 21a of the first plastic section 21 of the negative electrode terminal electrode 18, and is, for example, 0.2 mm. Therefore, the central section 15d of the negative electrode terminal electrode 18 can be brought into contact with the first conductive plate 5 without being gripped by the first section 21a. As described above, in the electrode laminate 11 of the energy storage module 4, the electrode plates 15 are laminated in a slightly deformed state.The degree of deformation of the electrode plate 15 increases towards the laminate end from the intermediate layers of the electrode laminate 11. In the present embodiment, the first conductive plate 5 is also in contact with the first section 21a. The conductive plates 5, which are provided as a pair, are not in contact with the second plastic section 22.

[0042] The swelling of the central section 15d with respect to the edge section 15c in the positive electrode terminal electrode 19 (the separation distance in the lamination direction D between the edge section 15c on the side of the second surface 15b and the central section 15d on the side of the second surface 15b in the positive electrode terminal electrode 19) is, for example, equal to the swelling of the central section 15d with respect to the edge section 15c of the negative electrode terminal electrode 18.

[0043] Fig. Figure 3 shows an enlarged cross-sectional view of a substantial section, showing the external appearance of a negative electrode terminal electrode when the internal pressure of an energy storage module in an energy storage device increases according to a reference example. Fig. Figure 4 shows an enlarged cross-sectional view of a substantial section, illustrating the external appearance of a positive electrode terminal electrode when the internal pressure of the energy storage module in the energy storage device according to the reference example increases. In an energy storage device 100 according to the reference example, unlike in the energy storage device 1 according to the exemplary embodiment, conductive plates 105 provided as a pair are arranged such that they do not overlap with the first plastic sections 21, which are located at the edge sections 15c of the negative electrode terminal electrode 18 and the positive electrode terminal electrode 19, which face each other in the lamination direction D (hereinafter referred to as the first plastic sections 21 of a pair of terminal electrodes), when viewed in the lamination direction D.The pair of conductive plates 105 is slightly smaller than the conductive plate 5 of the exemplary embodiment when viewed in the lamination direction D. The pair of conductive plates 105 is separated from the first plastic sections 21 in the direction perpendicular to the lamination direction D. The pair of conductive plates 105 is the same size as, for example, the central section 11c of the electrode laminate 11 when viewed in the lamination direction D. The pair of conductive plates 105 is arranged such that the central sections 11c of the electrode laminate 11 are sandwiched together. The pair of conductive plates 105 is in contact with the central sections 11c of the electrode laminate 11.

[0044] If, in the energy storage device 100, the internal pressures of the spaces V between the electrode plates 15 and 15 in the energy storage module 4 increase due to operating conditions or the like, a load generated in the intermediate layers of the electrode laminate 11 by the internal pressures of the spaces V adjacent to each other in the lamination direction D is relieved. Since the space V itself is also a small space, deformation of the bipolar electrode 14 will occur relatively easily.

[0045] On the other hand, unlike in the intermediate layers, the negative electrode terminal electrode 18 and the positive electrode terminal electrode 19, which are positioned at the laminate ends of the electrode laminate 11, do not cancel out a load generated by the internal pressures of the interior spaces V. Therefore, it can be assumed that with increasing internal pressure, the negative electrode terminal electrode 18 and the positive electrode terminal electrode 19 deform extraordinarily towards the outside of the electrode laminate 11 along the lamination direction D, as is the case in Fig. 3 and Fig.Figure 4 shows that if the negative electrode terminal 18 and the positive electrode terminal 19 deform excessively, excessive stresses are applied to the first plastic sections 21, and therefore there is a problem that the first plastic sections 21 may break. A further problem is that gaps may form between the first plastic section 21 and the negative electrode terminal 18, and between the first plastic section 21 and the positive electrode terminal 19. In particular, it is likely that the first plastic section 21 will break in the boundary section (connection section) between the section covered by the overhang section 22b of the second plastic section 22 and the section not covered by the overhang section 22b.Fracture of the first plastic section 21 can cause the electrolytic solution E to leak to the outside of the electrode laminate 11. The formation of gaps between the first plastic section 21 and the negative electrode terminal 18, and between the first plastic section 21 and the positive electrode terminal 19, can also cause leakage of the electrolytic solution E to the outside of the electrode laminate 11.

[0046] On the other hand, in the energy storage device 1, the pair of conductive plates 5 is arranged such that the first plastic sections 21 of the pair of terminal electrodes overlap when viewed in the lamination direction D. Therefore, even if the internal pressure of the energy storage module 4 increases, excessive deformation of the negative electrode terminal 18 and the positive electrode terminal 19 by the conductive plates 5 can be suppressed. Thus, breakage of the first plastic section 21 can be avoided. The formation of gaps between the first plastic section 21 and the negative electrode terminal 18 and between the first plastic section 21 and the positive electrode terminal 19 can also be avoided. As a result, leakage of the electrolytic solution E to the outside of the electrode laminate 11 can be prevented.

[0047] The pair of conductive plates 5 is arranged such that the first plastic sections 21 overlap over the entire circumferences of the edge sections 15c in the negative electrode connection electrode 18 and the positive electrode connection electrode 19, when viewed in the lamination direction D. Therefore, excessive deformation of the negative electrode connection electrode 18 and the positive electrode connection electrode 19 can be further suppressed by the pair of conductive plates 5.

[0048] The length L1 of the edge section 11b of the electrode laminate 11 in the lamination direction D is shorter than the length L2 of the middle section 11c of the electrode laminate 11 in the lamination direction D. Therefore, even if the first plastic section 21 is provided at the edge section 15c of the negative electrode connection electrode 18 on the side of the first surface 15a, the first conductive plate 5 can be brought into contact with the middle section 15d of the negative electrode connection electrode 18 on the side of the first surface 15a. In the first embodiment, the first plastic section 21 is also provided at the first surface 15a of the positive electrode connection electrode 19. However, the length L1 is shorter than the length L2, even if the first plastic section 21 is provided at the second surface 15b. Therefore, it is easy to bring the second conductive plate 5 into contact with the positive electrode connection electrode 19.

[0049] The first conductive plate 5 is in contact with the first plastic section 21. Therefore, excessive deformation of the negative electrode terminal electrode 18 by the first conductive plate 5 can be avoided even more effectively.

[0050] The present invention is not limited to the embodiment described above. For example, the energy storage device 1 of the embodiment comprises the plurality of energy storage modules 4 and the plurality of conductive plates 5; however, the energy storage device 1 can comprise at least one energy storage module 4 and a pair of conductive plates 5.

[0051] At least one of the pair of conductive plates 5 can be arranged such that it overlaps with the first plastic section 21 of the connecting electrode, which faces the conductive plate 5 in the lamination direction D, when viewed in the lamination direction D. That is, the other of the pair of conductive plates 5 does not have to overlap with the first plastic section 21 of the connecting electrode, which faces the conductive plate 5 in the lamination direction D, when viewed in the lamination direction D.

[0052] In the embodiment described above, the first plastic sections 21 in all bipolar electrodes 14, the negative electrode terminal electrode 18, and the positive electrode terminal electrode 19 are provided such that they have the same shape. Therefore, the pair of conductive plates 5 also overlaps with the other first plastic sections 21, except for the first plastic sections 21 in the terminal electrodes that face the conductive plates 5 in the lamination direction D. However, the pair of conductive plates 5 need not overlap with the other first plastic sections 21 when viewed in the lamination direction D. That is, all electrodes of the bipolar electrodes 14, the negative electrode terminal electrode 18, and the positive electrode terminal electrode 19 need not have the first plastic sections 21 having the same shape. Reference symbol list 1 Energy storage device 4 Energy storage module 5 conductive plates 11 Electrode laminate 11b marginal section 11c middle section 12 sealing elements 13 Separator 14 Bipolar electrode 15 Electrode plate 15a first area 15b second area 15c marginal section 16 positive electrode 17 negative electrode 18 Negative electrode connection electrode 19 Positive electrode connection electrode 21 first plastic section

Claims

[1] Energy storage device (1) comprising: an energy storage module (4); and a pair of conductive plates (5) arranged in such a way as to sandwich the energy storage module (4), wherein the energy storage module (4) has an electrode laminate (11) comprising a plurality of laminated bipolar electrodes (14) and a pair of terminal electrodes (18, 19) and a sealing body (12) designed to seal the electrode laminate (11), wherein the pair of connecting electrodes (18, 19) is arranged at laminate ends of the electrode laminate (11), and the connecting electrodes (18, 19) provided as a pair each have an electrode plate (15) and an active material layer (16, 17) which is provided on a surface of the electrode plate (15) which is opposite an inside of the electrode laminate (11), wherein the sealing body (12) has a pair of plastic sections (21, 22) which are provided on edge sections (15c) of the pair of connection electrodes (18, 19), wherein at least one conductive plate (5) from the pair of conductive plates (5) is arranged such that it faces a corresponding terminal electrode (18, 19) from the pair of terminal electrodes (18, 19) in a lamination direction (D) of the electrode laminate (11) and overlaps with a corresponding plastic section (21, 22) from the pair of plastic sections (21, 22) when viewed in the lamination direction (D), wherein the at least one conductive plate (5) is in direct contact with the electrode plate (15) of the corresponding connecting electrodes (18, 19) on a surface that faces away from the electrode laminate (11), wherein the active material layer (16, 17) of each terminal electrode (18, 19) is provided only on the surface of the electrode plate (15) which faces the inside of the electrode laminate (11), and wherein the at least one conductive plate (5) has a plurality of flow paths (5a) extending in a direction perpendicular to the lamination direction (D) and are arranged such that a coolant circulates through them. [2] Energy storage device (1) according to claim 1, wherein a conductive plate (5) is arranged such that it overlaps with the corresponding plastic section (21, 22) over an entire circumference of the edge section of the corresponding terminal electrode (18, 19) when viewed in the lamination direction (D). [3] Energy storage device (1) according to claim 1 or 2, wherein the length of an edge section of the electrode laminate (11) in the lamination direction (D) is shorter than the length of a middle section of the electrode laminate (11) in the lamination direction (D). [4] Energy storage device (1) according to one of claims 1 to 3, wherein the conductive plate (5) is in contact with the corresponding plastic section (21, 22). [5] Energy storage device (1) according to any one of claims 1 to 4, wherein each of the pair of conductive plates (5) is arranged such that it faces each of the pair of connecting electrodes (18, 19) in the lamination direction (D) of the electrode laminate (11) and overlaps with each of the pair of plastic sections (21, 22) when viewed in the lamination direction (D).

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