Electricity storage device

Abstract

The invention relates to a power storage device. A power storage device includes a first power storage cell (power storage cell), a second power storage cell (power storage cell), and a conductor member. Each of the first power storage cell and the second power storage cell includes an electrode terminal close to the conductor member. Each of the electrode terminal of the first power storage cell and the electrode terminal of the second power storage cell is connected to the conductor member via a conductive adhesive.

Description

Energy storage device Technical Field

[0001] This disclosure relates to an energy storage device. Background Technology

[0002] Chinese Unexamined Patent Application Publication No. 116686151 discloses an energy storage device comprising a plurality of energy storage cells fixed in a housing (outer shell cavity). The electrode terminals of each energy storage cell are positioned facing the bottom wall of the housing. Summary of the Invention

[0003] In the energy storage device described in Chinese Unexamined Patent Application Publication No. 116686151, connecting the energy storage cells and conductor components (e.g., busbars) and further maintaining the connection between them is not necessarily easy.

[0004] This disclosure has been made to address the aforementioned problems, and the purpose of this disclosure is to facilitate the connection of the battery cell and the conductor components and to maintain the connection between them.

[0005] One aspect of this disclosure provides an energy storage device. The energy storage device includes a first energy storage cell, a second energy storage cell, and a conductor member. Each of the first and second energy storage cells includes an electrode terminal adjacent to the conductor member. Each of the electrode terminals of the first and second energy storage cells is connected to the conductor member via a conductive adhesive.

[0006] According to this disclosure, it is convenient to connect the battery cell and the conductor component and maintain the connection between them. Attached Figure Description

[0007] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein like symbols denote like elements, and wherein:

[0008] Figure 1 shows an overview of an energy storage device according to an embodiment of the present disclosure;

[0009] Figure 2 shows the interior of the energy storage device according to the embodiment;

[0010] Figure 3 is an end view of the energy storage device taken along line III-III in Figure 2;

[0011] Figure 4 is an end view of the energy storage device taken along line IV-IV in Figure 2;

[0012] Figure 5 shows the connection between the battery cell and the wiring board shown in Figure 2; and

[0013] Figure 6 illustrates a method for connecting the battery cell and wiring board shown in Figure 2. Detailed Implementation

[0014] Embodiments of this disclosure will be described in detail with reference to the accompanying drawings. In all the drawings, the same or corresponding parts are indicated by the same symbols and their descriptions will not be repeated. In the drawings referred to in the following description, the X-axis, Y-axis, and Z-axis indicate three axes perpendicular to each other. In the following text, the directions indicated by the arrows of the X-axis, Y-axis, and Z-axis are indicated by a plus sign “+”, and the opposite directions are indicated by a minus sign “-”.

[0015] Figure 1 shows an overview of the energy storage device according to this embodiment.

[0016] Referring to Figure 1, the energy storage device B according to this embodiment includes a lower housing 100 (first housing member), an upper cover 110 (second housing member), and a common panel 120 (third housing member), and these components serve as the housing for the energy storage device B. The lower housing 100 opens upward (on the +Z side) and accommodates a plurality of energy storage cells and various components associated with these energy storage cells. As will be described in detail later, the lower housing 100 accommodates energy storage cells, a cooler, a junction box (hereinafter referred to as "J / B"), etc. (see Figure 2). The upper cover 110 and the common panel 120 are each fixed to the lower housing 100. The upper cover 110 is disposed above the lower housing 100 and serves as a cover for the lower housing 100. The common panel 120 is disposed below the lower housing 100 (on the -Z side of the lower housing 100) and is used to reduce the impact on the lower housing 100 caused by road surface interference. An exhaust channel is formed between the lower housing 100 and the common panel 120.

[0017] For example, with the energy storage device B installed on the vehicle, the -Z side faces downwards (vertically downwards), the +Z side faces upwards (vertically upwards), the -X side faces the front of the vehicle, and the +X side faces the rear of the vehicle. The energy storage device B can be used as a traction energy storage device, commonly referred to as a "battery pack." The vehicle can be a battery electric vehicle (BEV) or any other type of electric vehicle (xEV).

[0018] The lower part of Figure 1 shows the lower housing 100 in an empty state (without containing anything) when viewed from above (+Z side). The lower housing 100 includes a bottom wall 101 (bottom) and a peripheral wall 102 (peripheral portion). The bottom wall 101 includes regions R1 to R5. The peripheral wall 102 includes side walls W1 to W4. Side walls W1, W2, W3, and W4 correspond to the ends of the lower housing 100 on the -X side, +X side, -Y side, and +Y side, respectively. Side wall W2 includes side walls W21 to W23. Side walls W21 to W23 are located on the +X side of side walls W3 and W4, which extend in the X direction. Among them, side wall W22 is located furthest on the +X side. Side walls W21 and W23 are provided with brackets 121 and 122, respectively. Side wall W22 is provided with exhaust valves 151 and 152. Sidewall W22 is connected to sidewalls W3 and W4 via sidewalls W21 and W23, respectively. The opposite (-X side) ends of sidewalls W3 and W4 are connected to each other via sidewall W1 extending in the Y direction. Sidewalls W3 and W4 are provided with brackets 131 and 132, respectively. Sidewall W1 is provided with brackets 111 and 112. Each of sidewalls W1 to W4 stands upright from the outer perimeter of the bottom wall 101 toward the +Z side. The interior space of the lower housing 100 is surrounded by sidewalls W1 to W4. The energy storage device B is connected to the vehicle body (e.g., floor panel) by fastening brackets 111, 112, 121, 122, 131, and 132 to the vehicle floor member.

[0019] The bottom wall 101 is provided with partition walls 103 and 104 extending in the Y direction. Partition walls 103 and 104 can be fastened to the bottom wall 101. Partition wall 104 is located on the +X side of partition wall 103. Partition walls 103 and 104 stand upright from the bottom wall 101 toward the +Z side. Region R5 is a rectangular region located in the central portion of the lower housing 100 and defined by partition walls 103 and 104. Region R5 is the region where the wiring board 200 and the energy storage stacks S1 to S6 (see Figure 2) described later are arranged. Region R5 is located between partition walls 103 and 104 (inner side of partition wall 103 and inner side of partition wall 104). Each of partition walls 103 and 104 can be a transverse frame.

[0020] Region R5 has an opening h1 at the location where the battery cells are disposed. Each of the openings h1 is configured to face, in the Z direction, a valve 13 corresponding to one of the battery cells 10 described later (see Figure 3). The openings h1 are arranged in the X direction to form multiple rows of openings h1. The number of rows formed in the bottom wall 101 corresponds to the number of battery stacks. The openings h1 are, for example, elongated holes extending through the bottom wall 101. However, the shape of the openings h1 can be appropriately modified. The openings h1 are formed, for example, by stamping.

[0021] In this embodiment, cover members 141 to 146 are disposed in region R5 of the bottom wall 101. Therefore, all openings h1 formed in the bottom wall 101 are covered by cover members 141 to 146. Each of the cover members 141 to 146 includes a base 105 extending in the X direction and N covers 105a arranged in the X direction. In this embodiment, the number of battery cells included in a battery stack is also N. N is, for example, 20 or more and 50 or less. However, this disclosure is not limited thereto, and N can be 2 or more and less than 20, or greater than 50.

[0022] The base 105 may have an adhesive on one of its surfaces (adhesive surfaces). The base 105 may be, for example, an adhesive tape, such as a polypropylene (PP) tape. N covers 105a are formed on the base 105. In this embodiment, the covers 105a comprise mica. The N covers 105a of each of the cover members 141, 142, 143, 144, 145, 146 are formed to close an opening h1 located below a corresponding energy storage stack in the energy storage stacks S1, S2, S3, S4, S5, S6 (see FIG. 2) described later. The size of the cover 105a is equal to or greater than the size of the opening h1. For example, the N covers 105a can be formed on the base 105 by attaching N pieces of mica foil to the adhesive surface of the base 105. Alternatively, the N covers 105a can be formed on the base 105 by forming N through holes in the base 105 and providing mica foil in each through hole. Each of the cover components 141 to 146 is attached to the upper surface (+Z side surface) of the bottom wall 101 via, for example, an adhesive surface of the base 105. As described above, the portion of the lower housing 100 facing the valve 13 (FIG. 3) of the battery cell 10 comprises mica. Mica has excellent heat resistance and electrical insulation properties.

[0023] Regions R3 and R4 are respectively located on the -Y and +Y sides of region R5. Region R1 is located on the outer side of partition wall 103 (on the -X side). Region R2 is located on the outer side of partition wall 104 (on the +X side). Region R2 is the region where the battery circuit unit 30 (FIG. 2) is located. Region R2 is located at the end of the lower housing 100 on the +X side and is defined by partition wall 104 and side wall W2. In this embodiment, the bottom wall 101, peripheral wall 102, and partition walls 103 and 104 are each made of metal. However, the material of these walls can be appropriately changed.

[0024] Figure 2 shows the interior of the lower housing 100 (the interior of the energy storage device B) as viewed from above, with the upper cover 110 removed. Referring to Figure 2, the energy storage stacks S1 to S6, the cooling device 20, the battery circuit unit 30, and the wiring board 200 are housed between the lower housing 100 and the upper cover 110. Each of the energy storage stacks S1 to S6 includes N energy storage cells 10 arranged in the X direction. The construction of each energy storage cell will be described in detail later. The wiring board 200 has a wiring pattern for the energy storage stacks S1 to S6. The battery circuit unit 30 includes circuitry electrically connected to the energy storage stacks S1 to S6. The battery circuit unit 30 may be a single unit or may include multiple units.

[0025] The cooling device 20 includes ports 20A and 20B, pipes 21A and 21B extending in the Y direction, pipes 22A and 22B extending in the X direction, a plurality of coolers 22C extending in the Y direction, and a cooling pipe 23. These components are connected from the upstream side in the following order: port 20A, pipe 21A, pipe 22A, cooling pipe 23, pipe 22B, pipe 21B, and port 20B. Pipes 22A and 22B are connected to each other via coolers 22C (cooling plates) arranged in the X direction. In each battery stack S1 to S6, coolers 22C are disposed between adjacent battery cells. Adjacent battery cells are cooled by a cooling medium flowing through channels formed inside the coolers 22C. Each cooler 22C has a channel communicating with each pipe 22A and 22B. The cooling pipe 23 is configured to cool the battery circuit unit 30.

[0026] Referring to Figures 1 and 2, ports 20A and 20B are located on sidewall W1. Port 20B is located on the +Y side of port 20A. Pipes 21A and 21B are located in region R1. Pipes 22A and 22B are located in regions R3 and R4, respectively. Cooling pipe 23 is located in region R2. Cooler 22C is located in region R5. Cooling medium supplied from port 20A to pipe 21A flows to the -Y side through pipe 21A. Cooling medium that has entered pipe 22A from pipe 21A flows to the +X side through pipe 22A, i.e., to cooling pipe 23, and also flows into the channel in cooler 22C. Cooling medium entering cooler 22C from pipe 22A flows to the +Y side, i.e., to pipe 22B, while cooling the battery stacks S1 to S6. Cooling medium entering cooling pipe 23 from pipe 22A flows to the +Y side, i.e., to pipe 22B, while cooling battery circuit unit 30. Cooling medium entering pipe 22B from cooler 22C or cooling pipe 23 flows through pipe 22B to the -X side, i.e., to pipe 21B. Then, the cooling medium flows through pipe 21B to the -Y side and exits from port 20B. The cooling medium can be a liquid (such as water, oil, or antifreeze solution) or a gas.

[0027] In this embodiment, the wiring board 200 is disposed on the +Z side of the bottom wall 101, and the energy storage stacks S1 to S6 are disposed on the +Z side of the wiring board 200.

[0028] Figures 3 and 4 are end views of the energy storage device B taken along lines III-III and IV-IV in Figure 2, respectively. A perspective view of the energy storage cell 10 is shown on the left side of Figure 3.

[0029] As shown in the perspective view on the left side of Figure 3, the battery cell 10 includes a housing 10a and an electrode assembly 10b housed within the housing 10a. The housing 10a is a cuboid housing. The electrode assembly 10b may include one or more wound bodies (e.g., two wound bodies). The wound bodies have a structure in which, for example, cathode and anode sheets are wound, with separators inserted therebetween. Each of the cathode and anode sheets includes an electrode foil and a layer of active material. The battery cell 10 is a secondary battery, such as a lithium-ion battery, a nickel-metal hydride battery, or a sodium-ion battery. In this embodiment, a liquid lithium-ion battery is used as the battery cell 10. The housing 10a contains an electrolyte solution and the electrode assembly 10b. The secondary battery can be of any type and can be, for example, an all-solid-state secondary battery. A stack (e.g., a stack in which cathode and anode sheets are stacked and separators are inserted therebetween) may be used instead of the wound bodies.

[0030] The battery cell 10 has electrode terminals 11, 12 and a valve 13 on the same surface. Specifically, the electrode terminals 11, 12 and the valve 13 are disposed on surface F10 of housing 10a. Surface F10 corresponds to the end face of one side of battery cell 10 in the height direction (Z direction). Valve 13 serves as an vent valve. Housing 10a is substantially kept in a sealed state. However, when the pressure inside housing 10a exceeds a first reference value, valve 13 opens to reduce the pressure inside housing 10a. Electrode terminals 11 and 12 are electrically connected to the cathode and anode plates of electrode assembly 10b, respectively, and serve as cathode terminals and anode terminals, respectively. The portion of housing 10a surrounding electrode terminals 11, 12 may be made of insulating material, and other portions of housing 10a may be made of metal. However, this disclosure is not limited thereto, and housing 10a may be made of any material.

[0031] In this embodiment, the individual cells included in the energy storage stacks S1 to S6 have the same structure (the structure shown in FIG. 3). Using the same type of individual cells 10 to form the energy storage stacks S1 to S6 facilitates the manufacture of the energy storage device B and reduces manufacturing costs. However, this disclosure is not limited thereto, and each energy storage stack may include multiple types of individual cells. The number of energy storage stacks can be appropriately varied. The number of energy storage stacks may be one or more.

[0032] The individual cells included in the energy storage stacks S1 to S6 are electrically connected via a wiring pattern on a wiring board 200. The wiring board 200 is, for example, a panel with a wiring pattern. An example of the wiring pattern of the wiring board 200 is shown in the lower part of Figure 2.

[0033] Specifically, the wiring board 200 includes a rectangular insulating substrate 201, a plurality of conductor members 211, a plurality of conductor members 212, a plurality of conductor members 213, a plurality of conductor members 214, a plurality of conductor members 215, a plurality of conductor members 216, conductor members 221 to 223, and conductor members 231 to 236. The insulating substrate 201 is made of, for example, resin.

[0034] Each conductor member 211 is electrically connected to multiple energy storage cells in the energy storage stack S1. Each conductor member 212 is electrically connected to multiple energy storage cells in the energy storage stack S2. Each conductor member 213 is electrically connected to multiple energy storage cells in the energy storage stack S3. Each conductor member 214 is electrically connected to multiple energy storage cells in the energy storage stack S4. Each conductor member 215 is electrically connected to multiple energy storage cells in the energy storage stack S5. Each conductor member 216 is electrically connected to multiple energy storage cells in the energy storage stack S6.

[0035] Conductor component 221 electrically connects to energy storage stacks S1 and S2. Conductor component 222 electrically connects to energy storage stacks S3 and S4. Conductor component 223 electrically connects to energy storage stacks S5 and S6. Conductor components 231, 232, 233, 234, 235, and 236 respectively electrically connect energy storage stacks S1, S2, S3, S4, S5, and S6 to battery circuit unit 30.

[0036] In this embodiment, the wiring pattern of the wiring board 200 is formed by the aforementioned conductor members. Each of conductor members 211 to 216, 221 to 223, and 231 to 236 is, for example, a plate-shaped member made of metal. Each of conductor members 221 to 223 may be a U-shaped plate member. Each conductor member may be a busbar. In this embodiment, each conductor member is fixed in a corresponding recess formed in the surface (+Z side surface) of the insulating substrate 201. The lower part of each conductor member is embedded in the insulating substrate 201. However, the recess (step) for the conductor member does not need to be formed in the surface of the insulating substrate 201. Each conductor member may be bonded to a flat surface of the insulating substrate 201. Each conductor member may be made of any material and may have any shape.

[0037] Wiring board 200 is electrically connected to battery circuit unit 30. As shown in FIG2, battery circuit unit 30 includes a general positive terminal 31, a general negative terminal 32, a J / B 33, a fuse 34, and wires L1 to L4. The general positive terminal 31 is located at the end of the cathode side of all energy storage stacks S1 to S6 (all energy storage cells). The general negative terminal 32 is located at the end of the anode side of all energy storage stacks S1 to S6 (all energy storage cells). Wire L1 electrically connects conductor member 232 and conductor member 233. Wire L2 electrically connects conductor member 234 and conductor member 235. Fuse 34 is disposed on wire L2. Conductor member 236 is connected to general positive terminal 31. Wire L3 electrically connects general positive terminal 31 and J / B 33. Conductor member 231 is connected to general negative terminal 32. Wire L4 electrically connects general negative terminal 32 and J / B 33. J / B 33 accommodates various electrical devices. J / B 33 may include at least one of a relay, a fuse, a resistive element, a current sensor, and a connector (e.g., a connector to an on-board charger). Battery circuit unit 30 may also include either or both of a battery management system (BMS) and an electronic control unit (ECU).

[0038] The partition wall 104 may have openings for conductor members 231 to 236 to pass through. Alternatively, wires (e.g., cables) connected to the wiring board 200 may pass over the partition wall 104 and connect to the battery circuit unit 30. Partition walls 103 and 104 are not required. Any one or both of partition walls 103 and 104 may be omitted.

[0039] Each of the energy storage stacks S1 to S6 comprises the same number of energy storage cells and is arranged such that the positions of the energy storage cells are aligned between the energy storage stacks S1 to S6. Therefore, each group of six energy storage cells 10 arranged along the Y direction forms a row (a row along the Y direction). Multiple rows are arranged in the X direction. A total of "6×N" energy storage cells 10 are arranged in a matrix with six rows in the Y direction and N columns in the X direction. In the wiring pattern shown in Figure 2, multiple parallel-connected units are connected in series. The N energy storage cells 10 are arranged such that the positional relationship between electrode terminals 11 (cathode terminals) and electrode terminals 12 (anode terminals) is reversed for every two energy storage cells 10. Each of the conductor members 211 to 216 is connected in parallel to every two energy storage cells of its corresponding energy storage stack, and the resulting parallel-connected units (parallel-connected energy storage cells) are connected in series. How the energy storage cells are connected can be appropriately varied. For example, the number of parallel-connected energy storage cells can be three or more, instead of two. All energy storage cells can be connected in series instead of forming parallel-connected units.

[0040] The insulating substrate 201 of the wiring board 200 has an opening h2 as shown in FIG. 3 at the same location in the XY plane as opening h1 (FIG. 1). The number of openings h2 is the same as the number of openings h1 (6×N), and each opening h2 faces the valve 13 of a corresponding battery cell 10 in the Z direction. The opening h2 is, for example, an elongated hole extending through the insulating substrate 201. The opening h2 has a larger dimension in the XY plane than the opening h1 (FIG. 1). In the XY plane, each opening h1 is located inside the corresponding opening h2. As shown in FIG. 3, each opening h2 is connected to the corresponding opening h1 via a corresponding cover 105a. The opening h2 is formed, for example, by stamping.

[0041] In the manufacture of the energy storage device B, for example, after the wiring board 200 is installed in the lower housing 100, the energy storage stacks S1 to S6 are installed on the wiring board 200, wherein the surface F10 of the energy storage cells is oriented downward in the vertical direction. The battery circuit unit 30 is connected to the wiring board 200, and the cooling device 20 is installed in the lower housing 100. As a result, the interior of the lower housing 100 is in the state shown in FIG. 2. The cooler 22C of the cooling device 20 can be installed in the lower housing 100 together with the energy storage stacks S1 to S6. Thereafter, the rest of the cooling device 20 can be placed in the lower housing 100, and each of the tubes 22A and 22B can be connected to the cooler 22C. The wiring board 200 and each of the battery circuit units 30 can be fixed to the lower housing 100 by an adhesive (e.g., silicone adhesive).

[0042] As shown in Figures 3 and 4, the upper cover 110 is bonded to the upper surface (+Z side surface) of the side walls W1 to W4 (only side walls W1 and W3 are shown in Figures 3 and 4) via, for example, adhesive 110b, and is further secured by bolts 110a. The common panel 120 is bonded to the lower surface (e.g., -Z side surface) of the side walls W1 to W4 via, for example, adhesive 120b. Although not shown in Figure 3, the tube 22A shown in Figure 2 is disposed in the space V3 between the side wall W3 and the battery cell 10 located at the -Y side end in the lower housing 100. Although not shown in Figure 4, the tube 21A shown in Figure 2 is disposed in the space V1 between the side wall W1 and the partition wall 103 in the lower housing 100.

[0043] An exhaust passage P1 is formed between the bottom wall 101 of the lower housing 100 and the common panel 120. Side walls W1 to W4 are hollow. As shown in Figure 3, an exhaust passage P3 is formed inside side wall W3. Although not shown in the figure, exhaust passages are also formed inside each of side walls W2 and W4 in a manner similar to exhaust passage P3 in side wall W3. These exhaust passages communicate with each other. Side wall W2 has exhaust ports connected to exhaust valves 151 and 152 (Figure 2). These exhaust ports communicate with the exhaust passages.

[0044] When the pressure inside the battery cell 10 exceeds a first reference value, valve 13 opens, as shown in FIG3. As a result, due to the pressure and heat of the gas discharged from the inside of the battery cell 10 through valve 13, an orifice facing valve 13 is formed in cover 105a. The gas discharged from the battery cell 10 passes through the orifice and flows into exhaust passage P1. When the pressure in the exhaust passage exceeds a second reference value, each of the exhaust valves 151 and 152 shown in FIG2 opens. The second reference value can be a pressure value lower than the first reference value. Exhaust valves 151 and 152 are, for example, check valves. When either or both of the exhaust valves 151 and 152 are open, the gas in each exhaust passage flows toward the opened exhaust valve and is discharged to the outside of the battery storage device B through the exhaust valve. The thickness of each cover 105a (FIG. 1) provided on the lower housing 100 is set to be sufficiently small such that an orifice is formed when valve 13 facing cover 105a is opened (e.g., when the valve is opened in a manner that could cause a fire).

[0045] A mica layer 120a (e.g., mica foil) is disposed on the inner (+Z side) surface of the common panel 120. The mica layer 120a may be provided to overlap with all covers 105a in the XY plane. The mica layer 120a protects the common panel 120 from substances (gases, electrolyte solutions, debris, etc.) emitted from the battery cells 10 through the covers 105a.

[0046] As shown in Figure 4, in each energy storage stack, the intermediate member 40 is disposed between two adjacent energy storage cells 10 along the X direction, and the end member 40a is disposed on the outside of the energy storage cell 10 located at the end along the X direction.

[0047] The intermediate component 40 includes the cooler 22C shown in FIG. 2, two insulating pads 41, and two shock-absorbing components 42 (only one is shown). Each of the two insulating pads 41 may be a resin film. Each of the two insulating pads 41 is located between the cooler 22C and the battery cell 10. The shock-absorbing components 42 are located at both ends of the intermediate component 40 in the Z direction and suppress the transmission of shocks to the cooler 22C. Although FIG. 4 only shows the end of the intermediate component 40 on the +Z side, the end on the -Z side has the same structure.

[0048] The end member 40a includes the cooler 22C shown in FIG. 2, insulating pads 41, insulating pads 41a, and two shock-absorbing members 42a (only one is shown). The end member 40a has essentially the same structure as the intermediate member 40. In the end member 40a, one of the two insulating pads 41 in the intermediate member 40 is changed to an insulating pad 41a that is thicker than the insulating pad 41. The insulating pad 41a is located on the outside of the cooler 22C (on the side of the partition wall 103). This suppresses the transmission of external shocks to the energy storage units (energy storage stacks S1 to S6). The shock-absorbing members 42a are located at both ends of the end member 40a in the Z direction and suppress the transmission of shocks to the cooler 22C. Although FIG. 4 only shows the end of the end member 40a on the +Z side, the end on the -Z side has the same structure. Although Figure 4 only shows the end member 40a disposed between the partition wall 103 and the battery cell 10 located at the end on the -X side, the end member 40a is also disposed between the partition wall 104 and the battery cell 10 located at the end on the +X side.

[0049] As shown in Figures 3 and 4, each battery cell housed in the lower housing 100 includes electrode terminals 11 and 12 on the -Z side (the side of the wiring board 200). The electrode terminals 11 and 12 of each battery cell are connected to any conductive component of the wiring board 200 via a conductive adhesive 50. With this configuration, the electrode terminals of each battery cell and the conductive components of the wiring board 200 can be easily connected to each other. Furthermore, the electrical connection between them is maintained by the conductivity and adhesion of the conductive adhesive 50. The bonding with the conductive adhesive provides a wide tolerance for misalignment.

[0050] In the following text, the energy storage cell 10 located on the -X side (partition wall 103 side) of the two energy storage cells 10 shown in FIG4 will be referred to as "energy storage cell C1", and the energy storage cell 10 located on the +X side of the two energy storage cells 10 shown in FIG4 will be referred to as "energy storage cell C2". Energy storage cell C1 and energy storage cell C2 are examples of the "first energy storage cell" and "second energy storage cell" according to this disclosure, respectively.

[0051] Referring to Figure 4, battery cells C1 and C2 are arranged in a direction perpendicular to the vertical direction (Z direction) (X direction). The electrode terminals 12 of battery cells C1 and C2 are connected to the same conductor member 211 and oriented vertically downwards. The surface of the electrode terminal 12 of battery cell C1 on the -Z side (hereinafter referred to as the "first surface") has been roughened, for example, by etching. The surface of the electrode terminal 12 of battery cell C2 on the -Z side (hereinafter referred to as the "second surface") has also been roughened, for example, by etching. On the surface of the conductor member 211 (+Z side surface), the portion PT1 (first portion) connected to the electrode terminal 12 of battery cell C1 and the portion PT2 (second portion) connected to the electrode terminal 12 of battery cell C2 have also been roughened, for example, by etching. The portion PT1 of the conductor member 211 is the portion facing the electrode terminal 12 of battery cell C1 in the Z direction. The portion PT2 of conductor member 211 is the portion facing the electrode terminal 12 of the battery cell C2 in the Z direction. Each portion that has undergone roughening treatment has a greater surface roughness than the portion that has not undergone roughening treatment.

[0052] The first surface of the electrode terminal 12 of the battery cell C1 is connected to a portion PT1 of the conductor member 211 via a conductive adhesive 50 (more specifically, the first conductive adhesive 50a in FIG. 4). The second surface of the electrode terminal 12 of the battery cell C2 is connected to a portion PT2 of the conductor member 211 via a conductive adhesive 50 (more specifically, the second conductive adhesive 50b in FIG. 4). By subjecting each of portions PT1 and PT2 of the conductor member 211 to a roughening treatment, the bonding strength between each portion and the conductive adhesive 50 is improved. Each of portions PT1 and PT2 can be formed to the extent that it exhibits an anchoring effect. By subjecting each of the first surface of the electrode terminal 12 of the battery cell C1 and the second surface of the electrode terminal 12 of the battery cell C2 to a roughening treatment, the bonding strength between each of the first and second surfaces and the conductive adhesive 50 is improved. Each of the first and second surfaces can be formed to the extent that it exhibits an anchoring effect.

[0053] Roughening is not limited to etching. For example, minute protrusions and recesses can be formed on portions of PT1 and PT2, as well as on each of the first and second surfaces, by electroplating or anodizing. Different types of roughening can be used on the electrode terminals of the battery cell 10 and the conductor components of the wiring board 200.

[0054] Figure 5 shows the connector between the battery cell 10 and the wiring board 200. As a representative example, Figure 5 shows the structure of the connector between an electrode terminal (electrode terminal 12) and a conductor member (conductor member 211). Other connectors (more specifically, each connector between the electrode terminal of the battery cell 10 and the conductor member of the wiring board 200) have the same structure.

[0055] As shown in Figure 5, on the +Z side surface F21 of the conductor member 211, the portion facing the electrode terminal 12 (surface F21a) has minute protrusions and recesses due to the roughening treatment described above. Surface F21a has a greater surface roughness than the surrounding area. Surface F22 on the -Z side of the electrode terminal 12 also has minute protrusions and recesses due to the roughening treatment described above. As shown in the enlarged view at the bottom of Figure 5, the conductive adhesive 50 has solidified (cured) upon penetrating into the minute protrusions and recesses formed on each of surfaces F21a and F22. The surface roughness of surface F22 may be greater than that of surface F21a. Alternatively, the surface roughness of surface F21a may be greater than that of surface F22. Alternatively, these surfaces may have approximately the same surface roughness. Surface roughness is represented, for example, by the arithmetic mean roughness (Ra). However, this disclosure is not limited thereto, and the surface roughness of surfaces F21a and F22 can be compared in terms of maximum height (Rz).

[0056] The conductive adhesive 50 comprises a binder 51 and a plurality of filler particles 52 dispersed in the binder 51. The binder 51 comprises, for example, a resin. Each filler particle 52 is conductive. As shown on the left side of Figure 5, the conductive adhesive 50 with this configuration has high compliance with displacement in the X direction, displacement in the Y direction, and vibration in the Z direction. This helps to maintain the connection between the electrode terminals of the battery cell 10 and the conductor members of the wiring board 200 even after the battery storage device B is installed on the vehicle.

[0057] The binder 51 may comprise at least one of epoxy resin, phenolic resin, acrylic resin, polyurethane resin, and silicone resin. Using epoxy resin or phenolic resin as binder 51 helps increase the heat resistance of the conductive adhesive 50. Using acrylic resin, polyurethane resin, or silicone resin as binder 51 helps increase the compliance of the conductive adhesive 50. The filler particles 52 may comprise at least one of gold particles, silver particles, copper particles, nickel particles, and carbon particles. From a weight reduction point of view, carbon particles are particularly preferred.

[0058] The conductive adhesive 50 is, for example, a heat-reactive curing conductive adhesive. However, this disclosure is not limited thereto, and the conductive adhesive 50 may be a dry-curing conductive adhesive or a two-liquid conductive adhesive (a conductive adhesive that cures by a curing agent).

[0059] When mounting each battery cell onto the wiring board 200, uncured conductive adhesive 50 is applied to the joint of each conductor member of the wiring board 200 (e.g., surface F21a shown in FIG. 5), and then the battery stacks S1 to S6 are placed on the wiring board 200. The conductive adhesive 50 is cured while pressure is uniformly applied toward the wiring board 200 to each battery cell, for example by a pressure equalization device 600 shown in FIG. 6. As a result, the electrode terminals of each battery cell and the conductor members of the wiring board 200 are connected via the conductive adhesive 50. FIG. 6 illustrates a method for connecting the battery cell 10 and the wiring board 200 according to this embodiment.

[0060] Referring to Figure 6, the pressure equalization device 600 includes an oil supply device 610, a pipe 620, a check valve 620a, and a plurality of hydraulic cylinders 630. A hydraulic cylinder 630 is provided for each battery cell. Specifically, the hydraulic cylinders 630 are disposed on the +Z side end face of each battery cell included in the battery stacks S1 to S6. Each hydraulic cylinder 630 receives oil from the common oil supply device 610 and pressurizes the corresponding battery cell toward the -Z side (wiring board 200 side). The oil supply device 610 and the hydraulic cylinders 630 are connected to each other via the common pipe 620. The oil supply device 610 supplies oil to each hydraulic cylinder 630 through the pipe 620 until a predetermined hydraulic pressure is applied to each hydraulic cylinder 630. The check valve 620a disposed in the pipe 620 maintains the hydraulic pressure of each hydraulic cylinder 630 at the predetermined pressure. This maintains a state where equal hydraulic pressure is applied to the hydraulic cylinders 630. In this state, the conductive adhesive 50 at each joint is cured. Therefore, the distance between the electrode terminals of the battery cell 10 and the conductor members of the wiring board 200 at each joint is made uniform in the Z direction, and the thickness and density of the conductive adhesive 50 at each joint are also made uniform. This configuration helps to maintain the connection between the electrode terminals of the battery cell 10 and the conductor members of the wiring board 200 at each joint.

[0061] The various features of the above-mentioned energy storage device (features described in the implementation schemes and variations) can be applied in any combination.

[0062] Energy storage devices can be used for any purpose. They can be used in vehicles other than automobiles, mobile machinery (such as agricultural and construction machinery), unmanned moving objects, robots, or buildings.

[0063] The embodiments disclosed herein should be considered illustrative in all respects, not restrictive. The scope of this disclosure is set forth in the claims, not in the foregoing description of the embodiments, and is intended to include all variations thereof, which are equivalent in meaning and scope to the claims.

Claims

1. An energy storage device, comprising a first energy storage cell, a second energy storage cell, and a conductor component, wherein: Each of the first and second energy storage cells includes an electrode terminal near the conductor member; and each of the electrode terminals of the first and second energy storage cells is connected to the conductor member via a conductive adhesive.

2. The energy storage device according to claim 1, wherein: The first and second energy storage cells are arranged in a direction perpendicular to the vertical direction; and each of the electrode terminals of the first and second energy storage cells is connected to the conductor member while being oriented vertically downward.

3. The energy storage device according to claim 2 further includes an upper cover, a lower housing, a common panel, a wiring board, and a cooler, wherein: The first battery cell, the second battery cell, and the wiring board are housed between the lower housing and the upper cover; the wiring board includes a wiring pattern provided by a plurality of conductor members including the conductor members; the cooler is disposed between the first battery cell and the second battery cell; each of the first battery cell and the second battery cell also includes an exhaust valve on the surface where the electrode terminals are provided; and an exhaust passage is disposed between the lower housing and the common panel.

4. The energy storage device according to any one of claims 1 to 3, wherein, On the surface of the conductor member, the first portion to which the electrode terminals of the first energy storage cell are connected and the second portion to which the electrode terminals of the second energy storage cell are connected have been roughened.

5. The energy storage device according to claim 4, wherein: The first surface of the electrode terminal of the first battery cell has been roughened, and the first surface is connected to the first portion of the conductor member via a first conductive adhesive; Furthermore, the second surface of the electrode terminal of the second battery cell has been roughened, and the second surface is connected to the second portion of the conductor member via a second conductive adhesive.

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