JP7745580B2 - Energy storage module - Google Patents

Description

This disclosure relates to an energy storage module.

Japanese Patent No. 5919908 discloses a flat-plate laminated nonaqueous 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 XRD measurement of the carbon powder reveals a ratio I110/I004 of the peak intensity (I110) of the (110) plane of graphite crystals to the peak intensity (I110) of the (004) plane of graphite crystals, obtained by XRD measurement, of 0.6 or more. The carbon powder is a multilayered carbonaceous powder comprising 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 surface layer made of graphite with an R value of 0.1 or more, which is the ratio of the peak intensity at 1360 cm ^-1 to the peak intensity at 1580 cm ^-1 in an argon ion laser Raman spectrum. The publication states that a 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.

WO 2020/262081 discloses a power supply device comprising 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 faces of the battery block, and bind bars 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 comprises an 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 having greater rigidity than the elastic layer. The publication states that a power supply device with this configuration can absorb expansion of the battery cells over an extended period of time with the separator.

Patent No. 5919908 International Publication No. 2020/262081

By the way, the inventor would like to reduce the load on the restraint member.

The energy storage module disclosed herein includes multiple energy storage devices and a restraining member that restrains the multiple energy storage devices. The multiple 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, which is restrained by the restraining member while arranged with the wide sides facing each other. The electrode assembly has a laminated structure in which sheet-shaped positive electrodes and sheet-shaped negative electrodes are stacked with a separator interposed between them, and is housed in the case with the sheet-shaped positive electrodes and sheet-shaped negative electrodes stacked and facing the pair of narrow sides.

In an energy storage module with this configuration, the direction in which the positive and negative electrodes in the electrode assembly are stacked is different from the direction in which the energy storage device is restrained by the restraining member. This reduces the load on the restraining member.

The power storage device may include multiple wound electrode bodies, each having a pair of opposing flat surfaces, in which a long sheet-like positive electrode and a long sheet-like negative electrode are stacked with a long sheet-like separator interposed therebetween and wound in the sheet longitudinal direction. In the case, the multiple electrode bodies may be stacked with the flat surfaces facing the narrow side. This configuration makes it possible to achieve higher capacity, higher voltage, etc. for each power storage device and power storage module.

Multiple electrode bodies may be connected in parallel. This configuration allows the voltage of each electrode body to be constant.

Multiple electrode bodies may be connected in series. This configuration allows the energy storage device and energy storage module to have a high voltage.

The energy storage device may include a stacked electrode assembly 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 achieved in an energy storage module having an energy storage device with a stacked electrode assembly.

The case may have a pressing member inside that presses the electrode assembly against the narrow surface. This configuration allows a pressing force to be applied to the electrode assembly housed within the case.

FIG. 1 is a partially exploded perspective view of the energy storage module 1. FIG. FIG. 2 is a cross-sectional view of the electricity storage device 100. FIG. 3 is a schematic diagram of the electrode body 120. FIG. 4 is a cross-sectional view of the power storage device 200. FIG. 5 is a cross-sectional view of the power storage device 300. FIG. 6 is an exploded perspective view of the electrode body 320.

An embodiment of the technology disclosed herein is described below. The embodiment described herein is not intended to limit the technology disclosed herein. Unless otherwise specified, the technology disclosed herein is not limited to the embodiment described herein. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, identical reference numerals are used where appropriate to components and parts that perform the same function, and redundant explanations will be omitted. The reference numerals "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," which indicates 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."

In this specification, the term "electricity storage device" refers to a device in which charging and discharging occur through 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. Below, we will explain an embodiment in which a lithium-ion secondary battery is used as an example of the above-mentioned electricity storage device.

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.

Figure 2 is a cross-sectional view of the energy storage device 100. Figure 2 shows the cross-sectional structure along the wide surface 112a of the energy storage device 100. As shown in Figures 1 and 2, the energy storage device 100 has a case 110 and an electrode assembly 120. The case 110 is, for example, hexahedral in 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, "rectangular" includes shapes in which straight long and short sides are joined to each other via curves, and shapes in which at least one of the long and short sides is not straight but is curved, uneven, or bent and made up of multiple straight or curved lines.

As shown in Figures 1 and 2, the case 110 comprises 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 inside. 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.

Opening 112h is, for example, a location where sealing plate 114 is attached. Here, opening 112h is rectangular and is formed by the upper edges of a pair of wide surfaces 112a and the upper edges of a pair of narrow surfaces 112b. Although not shown in the figure, opening 112h has a recessed step along its inner edge. Sealing plate 114 is fitted into opening 112h and rests on the bottom of this step. Then, by joining (e.g., welding) sealing plate 114 to the step, the case body 112 and sealing plate 114 are integrated, and the case 110 is airtightly sealed.

The sealing plate 114 is, for example, a flat plate-shaped 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 attached. Here, the second mounting hole 119 is a through-hole.

Figure 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 a laminated structure 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. The electrode body 120 is housed in the case 110 in a state in which the stacking direction of the sheet-shaped positive electrode 122 and the sheet-shaped negative electrode 124 faces the pair of narrow surfaces 112b.

As shown in FIG. 3, the electrode body 120 is a wound electrode body 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 body 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 then press-molding this cylindrical body. Therefore, the electrode body 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 body 120 face the narrow surface 112b.

In the embodiment shown in Figures 1 and 2, the energy storage device 100 includes multiple electrode bodies 120. Here, the multiple electrode bodies 120 are stacked in the case 110 with the flat surfaces 120a facing the narrow surfaces 112b. As shown in Figure 2, the multiple electrode bodies 120 are arranged in the first direction P with their respective flat surfaces 120a facing each other. Within the case 110, the multiple electrode bodies 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 multiple arranged electrode bodies 120 faces the narrow surface 112b.

One end face 120b of the electrode body 120 faces the sealing plate 114, and the other end face 120c faces the bottom face 112c. End faces 120b and 120c are the stacked surfaces of the positive electrode 122, negative electrode 124, and separator 123, and are open surfaces. End face 120b is the surface on which the positive electrode tab 122t and negative electrode tab 124t are provided. End face 120c is the surface opposite end face 120b. As shown in Figures 2 and 3, the electrode body 120 is housed in the case body 112 so that the winding axis direction WD and the vertical direction of the energy storage device 100 are approximately parallel. The winding axis WL of the electrode body 120 is approximately parallel to the wide surface 112a and the narrow surface 112b, and is approximately perpendicular to the sealing plate 114.

As shown in FIG. 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 adhered 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 of the positive electrode 122 in the winding axis direction WD, as needed. Note that the constituent materials of the positive electrode active material layer 122a and the protective layer 122p may be those used in this type of electricity storage device (in this embodiment, a lithium-ion secondary battery) without any particular restrictions.

Multiple 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 Figure 3). The multiple positive electrode tabs 122t protrude toward one end of the winding axis direction WD (the upper end in Figure 3). The multiple 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 portion). In the embodiment shown in Figure 3, a protective layer 122p is provided on the base end side of the positive electrode tab 122t. In this embodiment, the multiple positive electrode tabs 122t protrude further in the winding axis direction WD than the separator 123. Multiple positive electrode tabs 122t are stacked at one end in the winding axis direction WD (the upper end in Figure 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 Figure 1, a positive electrode current collecting member 150 is joined to the positive electrode tab group 125.

As shown in FIG. 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 adhered to at least one surface of the negative electrode current collector foil 124c. Note that the constituent materials of the negative electrode active material layer 124a may be any materials used in this type of electricity storage device (in this embodiment, a lithium-ion secondary battery) without any particular restrictions.

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 Figure 3). The plurality of negative electrode tabs 124t protrude toward one end of the winding axis direction WD (the upper end in Figure 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 Figure 3) to form a negative electrode tab group 126. Therefore, the height (length in the winding axis direction WD) 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.

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 assembly 120. The separator 123 is, for example, a porous resin sheet made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP).

As shown in Figure 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 width of each sheet (in Figure 3, this is the length in the winding direction WD, excluding the positive electrode tab 122t and negative electrode tab 124t) is largest in the order of separator 123, negative electrode 124, and positive electrode 122.

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

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 both 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 a shaft 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 arranged 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.

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 connects 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 connects to the positive electrode tab group 125 of each electrode body 120. In the embodiment shown in FIGS. 1 and 2, it is a convex portion that protrudes from the plate-shaped portion 153 toward the electrode body 120. Here, the plate-shaped portion 153 is provided with second connection portions 152 in a number corresponding to the number of electrode bodies 120. The second connection portions 152 are also provided intermittently along the first direction P on 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.

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 a configuration similar to that of 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 a configuration similar to that of 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.

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), and the like. These may be used alone or in combination of two or more.

As shown in FIG. 2, insulating members 190 are disposed between the positive terminal 130 and the sealing plate 114, and between the negative terminal 140 and the sealing plate 114. The insulating members 190 are disposed, for example, between the first conductive portion 131 and the outer surface of the sealing plate 114, between the second conductive portion 132 and the inner surface of the sealing plate 114, and between the shaft portion 133 and the first mounting hole 118. The same is true for the negative side, where the insulating members 190 are disposed, for example, between the negative 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 molded as a single unit, or may be a combination of multiple parts molded separately.

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

In addition, in this embodiment, the multiple power storage devices 100 are restrained by restraining members R while aligned in the second direction Q. Here, the multiple power storage devices 100 are subjected to a restraining pressure in the second direction Q by the restraining members R. The restraining members R include 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 at one end and the other end in the second direction Q, sandwiching the multiple power storage devices 100 aligned in the same direction. The bind bar R2 spans the pair of end plates R1 and restrains the multiple power storage devices 100 in the second direction Q.

The energy storage module 1 can be used for a variety of purposes, but is particularly suitable as a power source (driving power source) for motors mounted on vehicles such as passenger cars and trucks. While there are no particular limitations on the type of vehicle, suitable examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

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 within the case 110. The plurality of energy storage devices 100 are restrained by the restraining member R in a state where 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 where the sheet-shaped positive electrode 122 and the sheet-shaped negative electrode 124 are stacked and facing the pair of narrow surfaces 112b.

In the energy storage module 1, the multiple energy storage devices 100 are arranged in a second direction Q with their wide surfaces 112a facing each other, and are constrained in the same direction. Meanwhile, within the case 110, the electrode assembly 120 has the positive electrode 122 and 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, the constraining member R applies a constraining pressure to the energy storage device 100 toward the wide surfaces 112a (in the second direction Q). Therefore, even if the energy storage device 100 expands and contracts due to the expansion and contraction of the energy storage module 1, the load on the restraining member R caused by this expansion and contraction can be reduced.

The energy storage device 100 may include multiple wound electrode bodies (electrode bodies 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 wound in the sheet longitudinal direction LD. Furthermore, in the case 110, the multiple electrode bodies 120 may be stacked with the flat surfaces 120a facing the narrow surface 112b. The effects of the technology disclosed herein are preferably achieved when the energy storage device 100 includes multiple electrode bodies 120 that are wound electrode bodies. Furthermore, by including multiple electrode bodies 120, it is possible to achieve higher capacities, higher voltages, and the like for each energy storage device 100 and the energy storage module 1.

It is also preferable that multiple electrode bodies 120 are connected in parallel. This allows the voltage of each electrode body 120 to be constant.

Alternatively, in other embodiments, the multiple electrode bodies 120 may be connected in series. Figure 4 is a cross-sectional view of the electricity storage device 200. Figure 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 bodies 120 are connected in series via the multiple connecting members 270.

The connecting member 270 is, for example, a member that connects two adjacent electrode bodies 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 bodies 120 in the first direction P is adjacent to the negative electrode tab group 126 of the other electrode body 120. Here, the connecting member 270 spans the positive electrode tab group 125 of one electrode body 120 and the negative electrode tab group 126 of the other electrode body 120. The connecting member 270 has, for example, a U-shaped cross section and includes a flat portion 271 and two connecting portions 272. The flat portion 271 is, for example, a portion that connects the two connecting portions 272. In this embodiment, the flat portion 271 is a substantially rectangular, flat portion. The flat portion 271 faces the inner surface of the sealing plate 114. The connecting 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.

The positive electrode current collecting member 250 is, for example, a member that electrically connects the positive electrodes of multiple electrode bodies 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, the portion that connects to the positive electrode terminal 130. In the embodiment shown in FIG. 4, it 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, the portion that connects 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 body 120 (here, the electrode body 120 at the left end in the first direction P) among the multiple electrode bodies 120 connected in series by multiple connection members 270.

The negative electrode current collecting member 260 is a member that electrically connects the negative electrodes of the multiple electrode bodies 120 connected in series to the negative electrode terminal 140. In the configuration 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 body 120 on the right end in the first direction P) of the multiple electrode bodies 120 connected in series by multiple connecting members 270. The configuration of the negative electrode current collecting member 260 is similar to that 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.

In the power storage device 200, multiple electrode bodies 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.

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

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

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 adhered 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 the short side of the positive electrode 322. Furthermore, the positive electrode tab 322t does not include the positive electrode active material layer 322a.

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 adhered 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 area and a negative electrode tab 324t. The coated area is, for example, the area 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 area of the negative electrode current collector foil 324c and the negative electrode active material layer 324a provided in the coated area. 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 the short side of the negative electrode 324. Furthermore, the negative electrode tab 324t does not include the negative electrode active material layer 324a.

In the electrode body 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 short side of the electrode. For example, multiple electrode bodies 320 are arranged overlapping each other in the first direction P so that all of the positive electrode tabs 322t are located on one side (the front side in FIG. 6 ) and all of the negative electrode tabs 324t are located on the other side (the rear side in FIG. 6 ). Separators 323 may be interposed between adjacent electrode bodies 320 to prevent short-circuiting. Furthermore, for the multiple electrode bodies 320 arranged in the first direction P, separators 323 may be interposed between one end (the left end in FIG. 5 ) of the electrode body 320 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.

In the configuration shown in FIG. 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 (e.g., welded) to each other. Therefore, it is preferable to provide the plate-shaped portion 353 of the positive electrode current collector 350 with a number of second connection portions 352 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 (e.g., 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.

As such, the electricity storage device 300 includes multiple electrode bodies 320. The electrode bodies 320 are stacked electrode bodies 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 multiple electrode bodies 320, which are stacked electrode bodies, instead of the electricity storage device 100 or the electricity storage device 200, the load on the restraining member R can be reduced.

Although not shown in the figures, 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 narrow surface 112b that presses the electrode body 120 or the electrode body 320. By providing a pressing member inside the case 110, a pressing force can be applied to the electrode body 120 or the electrode body 320. This can improve the performance of the power storage module 1.

As described above, specific aspects of the technology disclosed herein include those described in the following sections.
Item 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.
Item 3:
Item 3. The energy storage module according to item 1 or 2, wherein the plurality of electrode bodies are connected in parallel.
Item 4:
Item 3. The energy storage module according to item 1 or 2, wherein the plurality of electrode bodies are connected in series.
Item 5:
Item 5. The storage device includes a stacked electrode body in which the rectangular sheet-shaped positive electrode and the rectangular sheet-shaped negative electrode are stacked with the rectangular sheet-shaped separator interposed therebetween. The storage module according to any one of items 1 to 4.
Item 6:
Item 6. The energy storage module according to any one of items 1 to 5, wherein the case includes a pressing member therein that presses the electrode body against the narrow surface.

The above describes embodiments of the technology disclosed herein, but it is not intended that the technology disclosed herein be limited to the above embodiments. The technology disclosed herein may also be implemented in other embodiments. The technology described in the claims includes various modifications and variations of the embodiments exemplified above. For example, it is possible to replace part of the above embodiments with other modified embodiments, and it is also possible to add other modified embodiments to the above embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

REFERENCE SIGNS LIST 1 Energy storage module 100, 200, 300 Energy storage device 110 Case 120, 320 Electrode body 130 Positive electrode terminal 140 Negative electrode terminal 150, 250, 350 Positive electrode current collector 160, 260, 360 Negative electrode current collector 270 Connection member 190 Insulating member B Bus bar R Restraint member

Claims (6)

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. 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. The energy storage module described in claim 2, wherein the plurality of electrode bodies are connected in parallel. The energy storage module described in claim 2, wherein the plurality of electrode bodies are connected in series. The energy storage module described in claim 1, wherein the energy storage device comprises a stacked electrode assembly in which the rectangular sheet-shaped positive electrode and the rectangular sheet-shaped negative electrode are stacked with the rectangular sheet-shaped separator interposed therebetween. The electricity 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 :