Energy storage module

Abstract

To provide a technique of reducing a load applied to a binding member of a power storage module.SOLUTION: A power storage module 1 comprises a plurality of power storage devices 100 and a binding member R. The plurality of power storage devices 100 includes: a hexahedron-shaped case 110 that includes a pair of wide surfaces 112a that is opposite and a pair of narrow surfaces 112b that is opposite; and an electrode body 120 that is housed in the case 110. The plurality of power storage devices 100 is bound by the binding member R in a state where each wide surface 112a is arranged to be opposite. The electrode body 120 includes a lamination structure in which a sheet-like positive electrode 122 and a sheet-like negative electrode 124 are laminated via a separator 123. In addition, the electrode body 120 is housed in the case in the state where the sheet-like positive electrode 122 and the sheet-like negative electrode 124 are overlapped toward the pair of narrow surfaces 112b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Japanese Patent No. 5919908 discloses a flat-plate laminated non-aqueous electrolyte secondary battery having a positive electrode, a negative electrode, and an electrolyte layer interposed between the positive electrode and the negative electrode. In this flat-plate laminated battery, the negative electrode contains carbon powder as a negative electrode active material, and the ratio I110 / I004 of the peak intensity (I110) of the (110) plane of graphite crystals obtained by XRD measurement of the carbon powder to the peak intensity (I110) of the (004) plane of the graphite crystals, obtained by XRD measurement of the carbon powder, is 0.6 or more. The carbon powder also contains a core material made of graphite with an interlayer distance (d value) of 0.3380 nm or less in the d(002) plane, and a peak intensity (I110) of 1580 cm in the argon ion laser Raman spectrum. -1 Peak intensity at 1360 cm -1 The publication describes a multilayered carbonaceous powder having a surface layer made of graphite, and a graphite surface layer having an R value, which is the peak intensity ratio of the R value to the R value, of 0.1 or more. The publication also describes that the flat plate laminated battery can suppress expansion and contraction of the negative electrode during charging and discharging of the battery, thereby suppressing cell swelling and, ultimately, effectively preventing deformation of the entire flat plate laminated battery.

[0003] International Publication No. 2020 / 262081 discloses a power supply device that includes a battery block formed by stacking multiple battery cells in the thickness direction with a separator sandwiched between them, a pair of end plates disposed on both end surfaces of the battery block, and a bind bar connected to the pair of end plates and securing the battery block in a pressurized state via the end plates. In this power supply device, the separator includes a heat insulating layer, an elastic layer that absorbs expansion of the battery cells, and a stopper that limits the compression thickness of the elastic layer, with the stopper being more rigid than the elastic layer. The publication also describes that a power supply device with this configuration can absorb expansion of the battery cells over a long period of time with the separator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5919908 [Patent Document 2] International Publication No. 2020 / 262081 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, the present inventors wish to reduce the load on the restraining member. [Means for solving the problem]

[0006] The disclosed energy storage module includes a plurality of energy storage devices and a restraining member that restrains the plurality of energy storage devices. The plurality of energy storage devices include a hexahedral case having a pair of opposing wide sides and a pair of opposing narrow sides, and an electrode assembly housed in the case. The electrode assembly has a laminated structure in which a sheet-shaped positive electrode and a sheet-shaped negative electrode are stacked with a separator interposed therebetween, and the sheet-shaped positive electrode and the sheet-shaped negative electrode are housed in the case in a stacked state facing the pair of narrow sides.

[0007] In an energy storage module having such a configuration, the direction in which the positive and negative electrodes of the electrode assembly are stacked is different from the direction in which the energy storage device is restrained by the restraining member, thereby reducing the load on the restraining member.

[0008] The power storage device may include a plurality of wound electrode bodies, each of which has a pair of opposing flat surfaces, and which are formed by stacking a long sheet-like positive electrode and a long sheet-like negative electrode with a long sheet-like separator interposed therebetween and winding them in the sheet longitudinal direction. In the case, the plurality of electrode bodies may be stacked with the flat surfaces facing the narrow side. This configuration allows each power storage device and the power storage module to have higher capacity, higher voltage, and the like.

[0009] The plurality of electrode bodies may be connected in parallel, and with this configuration, the voltage of each electrode body can be made constant.

[0010] The plurality of electrode bodies may be connected in series. With this configuration, the power storage device and the power storage module can be made to have a high voltage.

[0011] The power storage device may include a stacked electrode body in which a rectangular sheet-shaped positive electrode and a rectangular sheet-shaped negative electrode are stacked with a rectangular sheet-shaped separator interposed therebetween. The effects of the technology disclosed herein are also preferably realized in a power storage module having a power storage device including the stacked electrode body.

[0012] The case may include a pressing member inside the case that presses the electrode assembly against the narrow surface. With this configuration, a pressing force can be applied to the electrode assembly housed in the case. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a partially exploded perspective view of the energy storage module 1. FIG. [Figure 2] FIG. 2 is a cross-sectional view of the electricity storage device 100. As shown in FIG. [Figure 3] FIG. 3 is a schematic diagram of the electrode body 120. As shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of the electricity storage device 200. [Figure 5] FIG. 5 is a cross-sectional view of the electricity storage device 300. [Figure 6]FIG. 6 is an exploded perspective view of the electrode body 320. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the technology disclosed herein will be described below. The embodiment described herein is not intended to limit the technology disclosed herein. The technology disclosed herein is not limited to the embodiment described herein unless otherwise specified. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, identical reference symbols are used for components and parts performing the same function, and redundant explanations will be omitted. The reference symbols "R," "L," "U," "D," "F," and "Rr" in the drawings represent "right," "left," "up," "down," "front," and "rear," respectively. Furthermore, the notation "A to B" indicating a numerical range means "greater than A and less than B" unless otherwise specified, and also encompasses the meaning of "greater than A and less than B."

[0015] In this specification, the term "electricity storage device" refers to a device in which charging and discharging occur by the movement of charge carriers between a pair of electrodes (positive and negative electrodes) via an electrolyte. Such electricity storage devices include secondary batteries such as lithium ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries; and capacitors such as lithium ion capacitors and electric double layer capacitors. In the following, an embodiment will be described in which a lithium ion secondary battery is used as an example of the above-mentioned electricity storage device.

[0016] First Embodiment Fig. 1 is a partially exploded perspective view of an energy storage module 1. Fig. 1 shows one of the energy storage devices 100 included in the energy storage module 1 in an exploded state. As shown in Fig. 1, the energy storage module 1 includes a plurality of energy storage devices 100 and a restraining member R. In the energy storage module 1, the plurality of energy storage devices 100 are restrained by the restraining member R in a state where they are arranged such that a pair of opposing wide surfaces 112a face each other.

[0017] FIG. 2 is a cross-sectional view of the electricity storage device 100. FIG. 2 shows a cross-sectional structure along a wide surface 112a of the electricity storage device 100. As shown in FIGS. 1 and 2, the electricity storage device 100 has a case 110 and an electrode assembly 120. The case 110 has, for example, a hexahedral shape and is a member that houses the electrode assembly 120. In this embodiment, the case 110 has a pair of opposing wide surfaces 112a and a pair of opposing narrow surfaces 112b. The case 110 also has a rectangular bottom surface 112c. The pair of opposing wide surfaces 112a extend from a pair of opposing long sides of the bottom surface 112c. The pair of opposing narrow surfaces 112b extend from a pair of opposing short sides of the bottom surface 112c. In this specification, the term "rectangular" includes shapes in which straight long and short sides are joined to each other via a curve, shapes in which at least one of the long and short sides is not straight but is curved, uneven, or bent and composed of multiple straight or curved lines, and the like.

[0018] 1 and 2, the case 110 includes a case body 112 and a sealing plate 114. The case body 112 is, for example, the main body of the case 110, which houses the electrode assembly 120 therein. In this embodiment, the case body 112 has an opening 112h, a pair of opposing wide surfaces 112a, a pair of opposing narrow surfaces 112b, and a bottom surface 112c. In this embodiment, the bottom surface 112c faces the opening 112h.

[0019] The opening 112h is, for example, a portion where the sealing plate 114 is attached. Here, the opening 112h is formed by being surrounded by the upper edges of the pair of wide surfaces 112a and the upper edges of the pair of narrow surfaces 112b, and has a rectangular shape. Although not shown in the drawings, the opening 112h has a recessed step along its inner edge. The sealing plate 114 is fitted into the opening 112h and placed on the bottom of this step. Then, the sealing plate 114 is joined (for example, welded) to the step, thereby integrating the case body 112 and the sealing plate 114 and hermetically sealing the case 110.

[0020] The sealing plate 114 is, for example, a flat plate-like member that seals the opening 112h. Therefore, the shape of the sealing plate 114 may correspond to the shape of the opening 112h. Here, when the sealing plate 114 is attached to the opening 112h, the sealing plate 114 faces the bottom surface 112c. As shown in FIGS. 1 and 2 , the sealing plate 114 is provided with a drain valve 115, a liquid inlet hole 117, a first mounting hole 118, and a second mounting hole 119. The drain valve 115 is, for example, a thin-walled portion. Here, the drain valve 115 is configured to break when the pressure inside the case 110 exceeds a predetermined value, thereby discharging gas inside the case 110 to the outside. The liquid inlet hole 117 is a portion through which the electrolyte is injected. A sealing plug 116 is attached to the liquid inlet hole 117. The first mounting hole 118 is, for example, a portion to which the positive electrode terminal 130 is attached. Here, the first mounting hole 118 is a through-hole. The second mounting hole 119 is a portion where, for example, the negative electrode terminal 140 is mounted. Here, the second mounting hole 119 is a through-hole.

[0021] 3 is a schematic diagram of the electrode body 120. The electrode body 120 is a power generating element of the electricity storage device 100, having, for example, a positive electrode and a negative electrode. The electrode body 120 has, for example, a laminated structure in which a sheet-shaped positive electrode 122 and a sheet-shaped negative electrode 124 are laminated with a separator 123 interposed therebetween. The electrode body 120 is housed in the case 110 in a state in which the sheet-shaped positive electrode 122 and the sheet-shaped negative electrode 124 are stacked such that the stacking direction faces the pair of narrow surfaces 112b.

[0022] As shown in FIG. 3, the electrode assembly 120 is a wound electrode assembly in which, for example, a sheet-shaped positive electrode 122 and a sheet-shaped negative electrode 124 are stacked with a separator 123 interposed therebetween and wound in the sheet longitudinal direction LD. The electrode assembly 120 can be produced, for example, by winding the positive electrode 122, the negative electrode 124, and the separator 123 into a cylindrical body and press-molding the cylindrical body. Therefore, the electrode assembly 120 has a flat shape and a pair of flat surfaces 120a (see FIGS. 1 and 2). The flat surfaces 120a are located at both ends in the stacking direction of the positive electrode 122 and the negative electrode 124. In this embodiment, the flat surfaces 120a of the electrode assembly 120 face the narrow surface 112b.

[0023] 1 and 2, the power storage device 100 includes a plurality of electrode assemblies 120. Here, the plurality of electrode assemblies 120 are stacked in the case 110 with the flat surfaces 120a facing the narrow surfaces 112b. As shown in FIG. 2, the plurality of electrode assemblies 120 are arranged in the first direction P with the respective flat surfaces 120a facing each other. Inside the case 110, the plurality of electrode assemblies 120 arranged in the first direction P are sandwiched between a pair of opposing narrow surfaces 112b. The flat surface 120a of each of the arranged plurality of electrode assemblies 120 faces the narrow surfaces 112b.

[0024] One end face 120b of the electrode assembly 120 faces the sealing plate 114, and the other end face 120c faces the bottom face 112c. Here, the end faces 120b and 120c are stacked surfaces of the positive electrode 122, the negative electrode 124, and the separator 123, and are open surfaces. The end face 120b is the surface on which the positive electrode tab 122t and the negative electrode tab 124t are provided. The end face 120c is the surface opposite to the end face 120b. As shown in FIGS. 2 and 3, the electrode assembly 120 is housed in the case body 112 so that the winding axis direction WD and the up-down direction of the electricity storage device 100 are substantially parallel. The winding axis WL of the electrode assembly 120 is substantially parallel to the wide surface 112a and the narrow surface 112b and is substantially perpendicular to the sealing plate 114.

[0025] 3, the positive electrode 122 has a long, strip-shaped positive electrode current collector foil 122c (e.g., aluminum foil) and a positive electrode active material layer 122a fixed to at least one surface of the positive electrode current collector foil 122c. Although not particularly limited, a protective layer 122p may be provided on one side edge portion in the winding axis direction WD of the positive electrode 122, as necessary. Note that, as the constituent materials of the positive electrode active material layer 122a and the protective layer 122p, materials used in this type of electricity storage device (in this embodiment, a lithium ion secondary battery) may be used without any particular limitation.

[0026] A plurality of positive electrode tabs 122t are provided at one end of the positive electrode current collector foil 122c in the winding axis direction WD (the upper end in FIG. 3). The plurality of positive electrode tabs 122t protrude toward one end of the positive electrode current collector foil 122c in the winding axis direction WD (the upper end in FIG. 3). The plurality of positive electrode tabs 122t are provided at intervals (intermittently) along the longitudinal direction LD of the positive electrode 122. The positive electrode tabs 122t are part of the positive electrode current collector foil 122c, and are portions of the positive electrode current collector foil 122c where the positive electrode active material layer 122a is not formed (active material layer unformed portions). In the embodiment shown in FIG. 3, a protective layer 122p is provided on the base end side of the positive electrode tab 122t. In this embodiment, the plurality of positive electrode tabs 122t protrude further than the separator 123 in the winding axis direction WD. The positive electrode tabs 122t are stacked at one end in the winding axis direction WD (the upper end in FIG. 3) to form a positive electrode tab group 125. Therefore, the height (length in the winding axis direction WD) of each positive electrode tab 122t and the width (length in the longitudinal direction LD) of each positive electrode tab 122t do not have to be the same. As shown in FIG. 1, a positive electrode current collecting member 150 is joined to the positive electrode tab group 125.

[0027] 3, the negative electrode 124 has a long, strip-shaped negative electrode current collector foil 124c (e.g., copper foil) and a negative electrode active material layer 124a fixed to at least one surface of the negative electrode current collector foil 124c. Note that, as a constituent material of the negative electrode active material layer 124a, any material used in this type of electricity storage device (in this embodiment, a lithium ion secondary battery) may be used without any particular limitation.

[0028] A plurality of negative electrode tabs 124t are provided at one end of the negative electrode current collector foil 124c in the winding axis direction WD (the upper end in FIG. 3). The plurality of negative electrode tabs 124t protrude toward one end of the winding axis direction WD (the upper end in FIG. 3). The plurality of negative electrode tabs 124t are provided at intervals (intermittently) along the longitudinal direction LD of the negative electrode 124. The negative electrode tabs 124t are part of the negative electrode current collector foil 124c, and are portions of the negative electrode current collector foil 124c where the negative electrode active material layer 124a is not formed (active material layer unformed portions). In this embodiment, the plurality of negative electrode tabs 124t protrude further in the winding axis direction WD than the separator 123. For example, the plurality of negative electrode tabs 124t are stacked at one end of the winding axis direction WD (the upper end in FIG. 3) to form a negative electrode tab group 126. For this reason, the height (length in the winding axis direction WD) of each negative electrode tab 124t and the width (length in the longitudinal direction LD) of each negative electrode tab 124t do not need to be the same. As shown in Fig. 1, a negative electrode current collecting member 160 is joined to the negative electrode tab group 126.

[0029] The separator 123 is a member that insulates the positive electrode active material layer 122a of the positive electrode 122 from the negative electrode active material layer 124a of the negative electrode 124. In this embodiment, the separator 123 forms the outer surface of the electrode body 120. The separator 123 is, for example, a porous sheet made of a resin such as a polyolefin resin, such as polyethylene (PE) or polypropylene (PP).

[0030] 3, in the electrode assembly 120, the lower end P3 of the separator 123 is the lowest, followed by the lower end P2 of the negative electrode 124, and the lower end P1 of the positive electrode 122 is the highest. The widths of the sheets (in FIG. 3, the length in the winding direction WD, excluding the positive electrode tab 122t and the negative electrode tab 124t) are largest in the order of separator 123, negative electrode 124, and positive electrode 122.

[0031] In this embodiment, the multiple electrode assemblies 120 are connected in parallel. The positive electrode 122 of each electrode assembly 120 is connected to, for example, a positive electrode terminal 130. As shown in FIGS. 1 and 2, the positive electrode tab group 125 of each electrode assembly 120 is connected to a positive electrode current collecting member 150. The positive electrode current collecting member 150 is connected to the positive electrode terminal 130. This electrically connects the positive electrode 122 of the electrode assembly 120 to the positive electrode terminal 130. Furthermore, the negative electrode 124 of each electrode assembly 120 is connected to, for example, a negative electrode current collecting member 160 and a negative electrode terminal 140. As shown in FIGS. 1 and 2, the negative electrode tab group 126 of each electrode assembly 120 is connected to the negative electrode current collecting member 160. The negative electrode current collecting member 160 is connected to the negative electrode terminal 140. This electrically connects the negative electrode 124 of the electrode assembly 120 to the negative electrode terminal 140.

[0032] The positive electrode terminal 130 is, for example, a member electrically connected to the positive electrode 122 of the electrode body 120. A bus bar B is attached to the positive electrode terminal 130 (see FIG. 1). As shown in FIG. 2, the positive electrode terminal 130 is inserted through the first mounting hole 118 and is disposed on the outside and inside of the case body 112. Here, the positive electrode terminal 130 has a first conductive portion 131, a second conductive portion 132, and an axis portion 133. The first conductive portion 131 is, for example, a portion connected to the bus bar B (see FIG. 1) in the energy storage module 1. In the embodiment shown in FIG. 2, the first conductive portion 131 is flat and disposed along the outer surface of the sealing plate 114. The second conductive portion 132 is, for example, a portion connected to the positive electrode current collecting member 150. In the embodiment shown in FIG. 2, the second conductive portion 132 is flat and disposed along the inner surface of the sealing plate 114. The shaft portion 133 is, for example, cylindrical and is inserted into the first mounting hole 118. In the embodiment shown in FIG. 2, the shaft portion 133 extends from the first conductive portion 131 and is connected to the second conductive portion 132. For example, the second conductive portion 132 may have a through-hole. In this case, the tip of the shaft portion 133 may be inserted into the through-hole and crimped. This allows the first conductive portion 131 and the second conductive portion 132 to be connected by the shaft portion 133. Alternatively, the first conductive portion 131, the second conductive portion 132, and the shaft portion 133 may be integrally molded. The positive electrode terminal 130 is made of, for example, aluminum or an aluminum alloy.

[0033] The positive electrode current collecting member 150 is, for example, a member that electrically connects the positive electrode tab 122t and the positive electrode terminal 130. As shown in FIGS. 1 and 2, the positive electrode current collecting member 150 has a first connection portion 151, a second connection portion 152, and a plate-shaped portion 153. The first connection portion 151 is, for example, a portion that is connected to the positive electrode terminal 130. In the embodiment shown in FIGS. 1 and 2, the first connection portion 151 is a convex portion that protrudes from the plate-shaped portion 153 toward the sealing plate 114. Here, the first connection portion 151 is joined (e.g., welded) to the second conductive portion 132 of the positive electrode terminal 130. The second connection portion 152 is, for example, a portion that is connected to the positive electrode tab group 125 of each electrode assembly 120. In the embodiment shown in FIGS. 1 and 2, the second connection portion 152 is a convex portion that protrudes from the plate-shaped portion 153 toward the electrode assembly 120. Here, the plate-shaped portion 153 is provided with second connection portions 152, the number of which corresponds to the number of electrode bodies 120. Furthermore, the second connection portions 152 are provided intermittently along the first direction P in the plate-shaped portion 153. The second connection portions 152 are joined (e.g., welded) to the positive electrode tab group 125, for example. The plate-shaped portion 153 is, for example, a portion that connects the second connection portions 152 and also connects to the first connection portions 151. In the embodiment shown in FIGS. 1 and 2, the plate-shaped portion 153 is plate-shaped and is arranged along the inner surface of the sealing plate 114. The positive electrode current collecting member 150 is made of, for example, aluminum or an aluminum alloy.

[0034] The negative electrode terminal 140 is, for example, a member electrically connected to the negative electrode 124 of the electrode body 120. A bus bar B is attached to the negative electrode terminal 140 (see FIG. 1 ). The negative electrode terminal 140 is made of, for example, copper or a copper alloy. The negative electrode terminal 140 may have the same configuration as the positive electrode terminal 130. Therefore, a description of the configuration of the negative electrode terminal 140 will be omitted here. The negative electrode current collecting member 160 is, for example, a member electrically connecting the negative electrode tab 124t and the negative electrode terminal 140. The negative electrode current collecting member 160 is made of, for example, copper or a copper alloy. The negative electrode current collecting member 160 may have the same configuration as the positive electrode current collecting member 150. Therefore, a description of the configuration of the negative electrode current collecting member 160 will be omitted here.

[0035] The electrolyte solution contains, for example, an electrolyte salt and a non-aqueous solvent. Examples of the electrolyte salt include LiPF6. The concentration of the electrolyte salt in the electrolyte solution is, for example, 0.7 mol / L to 1.3 mol / L. The non-aqueous solvent may be, for example, a carbonate. Examples of carbonates include ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), monofluoroethylene carbonate (MFEC), difluoroethylene carbonate (DFEC), monofluoromethyl difluoromethyl carbonate (F-DMC), trifluorodimethyl carbonate (TFDMC), etc. These may be used alone or in combination of two or more.

[0036] 2, insulating members 190 are disposed between the positive electrode terminal 130 and the sealing plate 114 and between the negative electrode terminal 140 and the sealing plate 114. The insulating members 190 are disposed, for example, between the first conductive part 131 and the outer surface of the sealing plate 114, between the second conductive part 132 and the inner surface of the sealing plate 114, and between the shaft part 133 and the first mounting hole 118. The same is true for the negative electrode side, where the insulating members 190 are disposed, for example, between the negative electrode terminal 140 and the outer surface of the sealing plate 114, between the inner surface of the sealing plate 114, and the second mounting hole 119. The insulating member 190 may be integrally molded or may be a combination of insulating members molded separately in multiple sections.

[0037] The energy storage module 1 includes, for example, a plurality of bus bars B. As shown in FIG. 1 , in the energy storage module 1, a plurality of energy storage devices 100 are arranged in a second direction Q in which a pair of opposing wide surfaces 112a face each other. In this embodiment, in two energy storage devices 100 adjacent to each other in the second direction Q, the positive electrode terminal 130 of one energy storage device 100 and the negative electrode terminal 140 of the other energy storage device 100 are adjacent to each other. The bus bar B spans between the positive electrode terminal 130 of one energy storage device 100 and the negative electrode terminal 140 of the other energy storage device 100.

[0038] In this embodiment, the multiple power storage devices 100 are arranged in the second direction Q and are restrained by a restraining member R. Here, a restraining pressure is applied to the multiple power storage devices 100 in the second direction Q by the restraining member R. The restraining member R includes a pair of end plates R1 and a bind bar R2. As shown in FIG. 1 , the pair of end plates R1 are flat and are disposed on one end side and the other end side in the second direction Q, sandwiching the multiple power storage devices 100 arranged in the same direction. The bind bar R2 is bridged across the pair of end plates R1 and restrains the multiple power storage devices 100 in the second direction Q.

[0039] The power storage module 1 can be used for a variety of purposes, and is particularly preferably used as a power source (driving power source) for motors mounted on vehicles such as passenger cars, trucks, etc. The type of vehicle is not particularly limited, but suitable examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0040] As described above, the energy storage module 1 includes a plurality of energy storage devices 100 and a restraining member R that restrains the plurality of energy storage devices 100. The plurality of energy storage devices 100 includes a hexahedral case 110 having a pair of opposing wide surfaces 112a and a pair of opposing narrow surfaces 112b, and an electrode assembly 120 housed in the case 110. The plurality of energy storage devices 100 are restrained by the restraining member R in a state in which the wide surfaces 112a face each other. The electrode assembly 120 has a layered structure in which a sheet-shaped positive electrode 122 and a sheet-shaped negative electrode 124 are stacked with a separator 123 interposed therebetween. The electrode assembly 120 is housed in the case in a state in which the sheet-shaped positive electrode 122 and the sheet-shaped negative electrode 124 are stacked and facing the pair of narrow surfaces 112b.

[0041] In the energy storage module 1, the multiple energy storage devices 100 are arranged in a second direction Q in which the wide surfaces 112a face each other, and are constrained in the same direction. Meanwhile, within the case 110, the electrode assembly 120 has the positive electrode 122 and the negative electrode 124 stacked in a first direction P facing the pair of narrow surfaces 112b. In other words, in the energy storage module 1, the direction in which the multiple energy storage devices 100 are arranged and constrained (second direction Q) is different from the stacking direction of the electrodes within the case 110 of the energy storage device 100 (first direction P). When the energy storage module 1 is charged and discharged, the electrode assembly 120 expands and contracts toward the narrow surfaces 112b of the case 110 (in the first direction P). Meanwhile, a constraining pressure is applied to the energy storage device 100 by the constraining member R toward the wide surfaces 112a (in the second direction Q). Therefore, even if the power storage device 100 expands and contracts due to the expansion and contraction of the power storage module 1, the load on the restraining member R due to this expansion and contraction can be reduced.

[0042] The electricity storage device 100 may include a plurality of wound electrode assemblies (electrode assemblies 120) each having a pair of opposing flat surfaces 120a, each of which is formed by stacking a long sheet-like positive electrode 122 and a long sheet-like negative electrode 124 with a long sheet-like separator 123 interposed therebetween and winding the stack in the sheet longitudinal direction LD. Furthermore, in the case 110, the plurality of electrode assemblies 120 may be stacked with the flat surfaces 120a facing the narrow surface 112b. The effect of the technology disclosed herein is preferably achieved when the electricity storage device 100 includes a plurality of electrode assemblies 120 that are wound electrode assemblies. Furthermore, by including a plurality of electrode assemblies 120, it is possible to achieve higher capacities, higher voltages, and the like for each of the electricity storage devices 100 and the electricity storage module 1.

[0043] Furthermore, it is preferable that the plurality of electrode bodies 120 are connected in parallel, which makes it possible to make the voltage of each electrode body 120 constant.

[0044] Alternatively, in other embodiments, the multiple electrode assemblies 120 may be connected in series. Fig. 4 is a cross-sectional view of the electricity storage device 200. Fig. 4 shows the cross-sectional structure of the electricity storage device 200 along the wide surface 112a. Here, the electricity storage device 200 has a positive electrode current collecting member 250, a negative electrode current collecting member 260, and multiple connecting members 270. In the electricity storage device 200, for example, the multiple electrode assemblies 120 are connected in series via the multiple connecting members 270.

[0045] The connection member 270 is, for example, a member that connects two adjacent electrode assemblies 120 in series in the first direction P. As shown in FIG. 4 , the positive electrode tab group 125 of one of two adjacent electrode assemblies 120 in the first direction P is adjacent to the negative electrode tab group 126 of the other electrode assembly 120. Here, the connection member 270 bridges the positive electrode tab group 125 of one electrode assembly 120 and the negative electrode tab group 126 of the other electrode assembly 120. The connection member 270 has, for example, a U-shaped cross section and includes a flat portion 271 and two connection portions 272. The flat portion 271 is, for example, a portion that connects the two connection portions 272. In this embodiment, the flat portion 271 is a substantially rectangular plate-shaped portion. The flat portion 271 faces the inner surface of the sealing plate 114. The connection portion 272 is, for example, a portion that is connected to the electrode tab group. In this embodiment, the two connection portions 272 extend from a pair of opposing sides of the flat portion 271. As shown in FIG. 4 , one of the two connection portions 272 is connected to the positive electrode tab group 125 of one of the two electrode bodies 120 adjacent to each other in the first direction P. The other of the two connection portions 272 is connected to the negative electrode tab group 126 of the other of the two electrode bodies adjacent to each other in the first direction P. The connection portion 272 and the electrode tab group may be joined by, for example, ultrasonic welding, laser welding, resistance welding, or the like. The connection member 270 is made of, for example, aluminum or an aluminum alloy.

[0046] The positive electrode current collecting member 250 is, for example, a member that electrically connects the positive electrodes of the plurality of electrode assemblies 120 connected in series to the positive electrode terminal 130. As shown in FIG. 4, the positive electrode current collecting member 250 has an L-shaped cross section and includes a first connection portion 251 and a second connection portion 252. The first connection portion 251 is, for example, a portion that is connected to the positive electrode terminal 130. In the embodiment shown in FIG. 4, the first connection portion 251 is plate-shaped and is joined (e.g., welded) to the second conductive portion 132 of the positive electrode terminal 130. The second connection portion 252 is, for example, a portion that is connected to the positive electrode tab group 125. In the embodiment shown in FIG. 4, the second connection portion 252 is joined (e.g., welded) to the positive electrode tab group 125 of the positive electrode assembly 120 (here, the electrode assembly 120 at the left end in the first direction P) among the plurality of electrode assemblies 120 connected in series by the plurality of connection members 270.

[0047] The negative electrode current collecting member 260 is a member that electrically connects the negative electrodes of the plurality of electrode assemblies 120 connected in series to the negative electrode terminal 140. In the embodiment shown in FIG. 4, the negative electrode current collecting member 260 is joined (e.g., welded) to the negative electrode tab group 126 of the negative electrode 120 (here, the electrode assembly 120 on the right end in the first direction P) of the plurality of electrode assemblies 120 connected in series by a plurality of connection members 270. The configuration of the negative electrode current collecting member 260 is similar to the configuration of the positive electrode current collecting member 250 described above. Therefore, a description of the configuration of the negative electrode current collecting member 260 will be omitted here.

[0048] In the power storage device 200, a plurality of electrode assemblies 120 are connected in series. This allows the power storage device 200 to have a high voltage. Therefore, by using the power storage device 200, the power storage module 1 can have a high voltage.

[0049] In the above-described embodiment, the electrode assembly 120 is a wound electrode assembly. However, the present invention is not limited to this. FIG. 5 is a cross-sectional view of an electricity storage device 300. FIG. 5 shows the cross-sectional structure of the electricity storage device 300 taken along the wide surface 112a. Here, the electricity storage device 300 includes a plurality of electrode assemblies 320, a positive electrode current collecting member 350, and a negative electrode current collecting member 360.

[0050] Fig. 6 is an exploded perspective view of the electrode assembly 320. Fig. 6 shows the layer structure of each sheet in the electrode assembly 320. As shown in Fig. 6, the electrode assembly 320 is a laminated electrode assembly in which a rectangular sheet-shaped positive electrode 322 and a rectangular sheet-shaped negative electrode 324 are laminated with a rectangular sheet-shaped separator 323 interposed therebetween. In this embodiment, the rectangular sheet-shaped positive electrode 322, the rectangular sheet-shaped negative electrode 324, and the rectangular sheet-shaped separator 323 are housed in the case 110 in a stacked state with the narrow surface 112b facing the stacked surface.

[0051] As shown in FIG. 6, the positive electrode 322 includes a positive electrode current collector foil 322c and a positive electrode active material layer 322a fixed to at least one surface of the positive electrode current collector foil 322c. Here, the positive electrode current collector foil 322c includes a rectangular coated area and a positive electrode tab 322t. The coated area is, for example, the area where the positive electrode active material layer 322a is provided. In this specification, the "rectangular sheet-shaped positive electrode 322" refers to the rectangular coated area of ​​the positive electrode current collector foil 322c and the positive electrode active material layer 322a provided in the coated area. The positive electrode tab 322t is, for example, a portion electrically connected to the positive electrode current collector member 350. In this embodiment, the positive electrode tab 322t protrudes outward from one end of a short side of the positive electrode 322. The positive electrode tab 322t is not provided with the positive electrode active material layer 322a.

[0052] As shown in FIG. 6 , the negative electrode 324 includes a negative electrode current collector foil 324c and a negative electrode active material layer 324a fixed to at least one surface of the negative electrode current collector foil 324c. Here, the negative electrode current collector foil 324c includes a rectangular coated region and a negative electrode tab 324t. The coated region is, for example, the region where the negative electrode active material layer 324a is provided. In this specification, the "rectangular sheet-shaped negative electrode 324" refers to the rectangular coated region of the negative electrode current collector foil 324c and the negative electrode active material layer 324a provided in the coated region. The negative electrode tab 324t is, for example, a portion electrically connected to the negative electrode current collector member 360. In this embodiment, the negative electrode tab 324t protrudes outward from one end of a short side of the negative electrode 324. The negative electrode tab 324t is not provided with the negative electrode active material layer 324a.

[0053] In the electrode assembly 320, a positive electrode tab 322t protrudes from one of the short sides of the electrode, and a negative electrode tab 324t protrudes from the other of the short sides of the electrode. For example, the multiple electrode assemblies 320 are arranged overlapping each other in the first direction P so that all of the positive electrode tabs 322t are arranged on one side (the front side in FIG. 6 ) and all of the negative electrode tabs 324t are arranged on the other side (the rear side in FIG. 6 ). Separators 323 may be interposed between adjacent electrode assemblies 320 to prevent short-circuiting between them. Furthermore, for the multiple electrode assemblies 320 arranged, a separator 323 may be interposed between one end (the left end in FIG. 5 ) in the first direction P and the other end (the right end in FIG. 5 ) in the same direction and the inner surface of the case body 112 to prevent short-circuiting between them.

[0054] 5, the positive electrode tab 322t of each electrode body 320 and the second connection portion 352 of the positive electrode current collector 350 are joined (for example, welded) to each other. For this reason, it is preferable to provide the plate-shaped portion 353 of the positive electrode current collector 350 with second connection portions 352 in a number corresponding to the number of electrode bodies 320 housed in the case 110. Furthermore, the first connection portion 351 of the positive electrode current collector 350 is joined (for example, welded) to the second conductive portion 132 of the positive electrode terminal 130. The same is true for the negative electrode side, where the negative electrode tab 324t of each electrode body 320 is joined to the negative electrode current collector 360. Furthermore, the negative electrode current collector 360 is joined to the negative electrode terminal 140.

[0055] As described above, the electricity storage device 300 includes a plurality of electrode assemblies 320. The electrode assembly 320 is a stacked electrode assembly in which rectangular sheet-shaped positive electrodes 322 and rectangular sheet-shaped negative electrodes 324 are stacked with rectangular sheet-shaped separators 323 interposed therebetween. Even when an electricity storage module 1 is constructed using an electricity storage device including a plurality of electrode assemblies 320 that are stacked electrode assemblies, instead of the electricity storage device 100 or the electricity storage device 200, the load on the restraining member R can be reduced.

[0056] Although not shown in the drawings, in any of the above-described power storage device 100, power storage device 200, and power storage device 300, the case 110 may have a pressing member inside the case 110 that presses the electrode assembly 120 or the electrode assembly 320 against the narrow surface 112b. By providing a pressing member inside the case 110, a pressing force can be applied to the electrode assembly 120 or the electrode assembly 320. This can improve the performance of the power storage module 1.

[0057] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Section 1: A plurality of power storage devices; a restraining member that restrains the plurality of power storage devices; Equipped with The plurality of power storage devices The battery includes a hexahedral case having a pair of opposing wide surfaces and a pair of opposing narrow surfaces, and an electrode assembly housed in the case, The wide surfaces are arranged so as to face each other and are restrained by the restraining member, The electrode body is The battery has a laminated structure in which a sheet-shaped positive electrode and a sheet-shaped negative electrode are laminated with a separator interposed therebetween, and the sheet-shaped positive electrode and the sheet-shaped negative electrode are housed in the case in a state in which they are stacked with the pair of narrow surfaces facing each other. Energy storage module. Item 2; The power storage device includes, as the electrode body, a plurality of wound electrode bodies each having a pair of opposing flat surfaces, in which the long sheet-like positive electrode and the long sheet-like negative electrode are stacked with the long sheet-like separator interposed therebetween and wound in a sheet longitudinal direction; Item 2. The energy storage module according to item 1, wherein in the case, the plurality of electrode bodies are stacked with the flat surfaces facing the narrow surfaces. Section 3: Item 3. The energy storage module according to item 1 or 2, wherein the plurality of electrode bodies are connected in parallel. Section 4: Item 3. The energy storage module according to item 1 or 2, wherein the plurality of electrode bodies are connected in series. Section 5: Item 5. The energy storage module according to any one of items 1 to 4, wherein the energy storage device includes a stacked electrode body in which the positive electrode and the negative electrode each have a rectangular sheet shape and are stacked with the separator each having a rectangular sheet shape interposed therebetween. Item 6: 6. The electricity storage module according to any one of items 1 to 5, wherein the case includes a pressing member therein that presses the electrode assembly against the narrow surface.

[0058] Although the embodiments of the technology disclosed herein have been described above, it is not intended that the technology disclosed herein be limited to the above-described embodiments. The technology disclosed herein may also be implemented in other embodiments. The technology described in the claims includes various modifications and alterations of the above-described exemplary embodiments. For example, it is possible to replace part of the above-described embodiments with other modified embodiments, and it is also possible to add other modified embodiments to the above-described embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate. [Explanation of symbols]

[0059] 1. Energy storage module 100, 200, 300 Energy storage devices 110 cases 120, 320 electrode body 130 Positive terminal 140 Negative terminal 150, 250, 350 Positive electrode current collecting material 160, 260, 360 Negative electrode current collecting member 270 Connecting members 190 Insulating material B busbar R restraining member

Claims

1. A plurality of power storage devices; a restraining member that restrains the plurality of power storage devices; Equipped with The plurality of power storage devices The battery includes a hexahedral case having a pair of opposing wide surfaces and a pair of opposing narrow surfaces, and an electrode assembly housed in the case, The wide surfaces are arranged so as to face each other and are restrained by the restraining member, the case includes a case body having an opening, the pair of wide surfaces, and the pair of narrow surfaces, and a sealing plate that seals the opening of the case body, The electrode body is the battery has a laminated structure in which a sheet-shaped positive electrode and a sheet-shaped negative electrode are laminated with a separator interposed therebetween, and the sheet-shaped positive electrode and the sheet-shaped negative electrode are housed in the case in a state in which they are stacked with the pair of narrow sides facing each other; a positive electrode tab and a negative electrode tab protruding from the end on the sealing plate side; Energy storage module.

2. The power storage device includes, as the electrode body, a plurality of wound electrode bodies each having a pair of opposing flat surfaces, in which the long sheet-like positive electrode and the long sheet-like negative electrode are stacked with the long sheet-like separator interposed therebetween and wound in a sheet longitudinal direction; The energy storage module according to claim 1 , wherein the plurality of electrode bodies are stacked in the case with the flat surfaces facing the narrow surface.

3. The energy storage module according to claim 2 , wherein the plurality of electrode bodies are connected in parallel.

4. The energy storage module according to claim 2 , wherein the plurality of electrode bodies are connected in series.

5. 2. The energy storage module according to claim 1, wherein the energy storage device comprises a stacked electrode body in which the positive electrode and the negative electrode each have a rectangular sheet shape and are stacked with the separator each having a rectangular sheet shape interposed therebetween.

6. The power storage device further comprises: a positive electrode terminal and a negative electrode terminal attached to the sealing plate; disposed between the sealing plate and the end of the electrode body, a positive electrode current collecting member that connects the positive electrode terminal and the positive electrode tab; a negative electrode current collecting member that connects the negative electrode terminal and the negative electrode tab; The storage module according to any one of claims 1 to 5, comprising:

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