Energy storage device

Abstract

The present invention provides an energy storage device that facilitates the connection between energy storage cells and conductive members, and the maintenance of these connections. [Solution] The energy storage device B comprises a first energy storage cell (energy storage cell C1), a second energy storage cell (energy storage cell C2), and a conductor member 211. Each of the first and second energy storage cells has an electrode terminal 12 on the conductor member 211 side. The electrode terminal 12 of the first energy storage cell and the electrode terminal 12 of the second energy storage cell are connected to the conductor member 211 via a conductive adhesive 50.

Description

Technical Field

[0001] The present disclosure relates to a power storage device.

Background Art

[0002] Chinese Patent Application Publication No. 116686151 (Patent Document 1) discloses a power storage device including a plurality of power storage cells fixed in a case (accommodation cavity). The electrode terminals of each power storage cell are provided facing the bottom wall of the case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the power storage device described in Patent Document 1 above, it is not always easy to connect a power storage cell and a conductor member (for example, a bus bar), and further, to maintain their connection.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to facilitate the connection between a power storage cell and a conductor member and the maintenance of these connections.

Means for Solving the Problems

[0006] According to one aspect of the present disclosure, a power storage device is provided. The power storage device includes a first power storage cell, a second power storage cell, and a conductor member. Each of the first power storage cell and the second power storage cell has an electrode terminal on the conductor member side. 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.

Effects of the Invention

[0007] According to this disclosure, it becomes possible to facilitate the connection between energy storage cells and conductive members, and the maintenance of these connections. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram illustrating the outline of an energy storage device according to an embodiment of the present disclosure. [Figure 2] This diagram shows the inside of the energy storage device according to this embodiment. [Figure 3] Figure 2 is an end view of the energy storage device along line III-III. [Figure 4] Figure 2 is an end view of the energy storage device on the IV-IV line. [Figure 5] This figure shows the connection points of the energy storage cell and the wiring board shown in Figure 2. [Figure 6] Figure 2 is a diagram illustrating the connection method for the energy storage cell and the wiring board shown. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their descriptions will not be repeated. In the drawings used below, the X-axis, Y-axis, and Z-axis refer to three mutually orthogonal axes. Hereafter, the direction indicated by the arrows on the X-axis, Y-axis, and Z-axis will be indicated by a "+" sign, and the opposite direction will be indicated by a "-" sign.

[0010] Figure 1 is a diagram illustrating the outline of the energy storage device according to this embodiment.

[0011] Referring to Figure 1, the energy storage device B according to this embodiment includes a lower case 100 (first housing member), an upper cover 110 (second housing member), and a shear panel 120 (third housing member), which function as the housing of the energy storage device B. The lower case 100 opens upward (towards the +Z side) and houses a plurality of energy storage cells and various components related to these energy storage cells. As will be described in detail later, the lower case 100 houses the energy storage cells, a cooler, and a junction box (hereinafter referred to as "J / B") (see Figure 2). The upper cover 110 and the shear panel 120 are fixed to the lower case 100. The upper cover 110 is positioned above the lower case 100 and functions as a lid for the lower case 100. The shear panel 120 is positioned below the lower case 100 (towards the -Z side) and suppresses impacts to the lower case 100 due to road surface interference. Furthermore, an exhaust passage is formed between the lower case 100 and the share panel 120.

[0012] When the energy storage device B is mounted on the vehicle, for example, the -Z side is downward (downward in the vertical direction), the +Z side is upward (upward in the vertical direction), the -X side is the front of the vehicle, and the +X side is the rear of the vehicle. The energy storage device B may function as a drive energy storage device, commonly referred to as a "battery pack". The vehicle may be an electric vehicle (BEV) or another electric vehicle (xEV).

[0013] The lower part of Figure 1 shows a view of the lower case 100 in an empty state (nothing contained inside) as seen from above (+Z side). The lower case 100 has a bottom wall 101 (bottom) and a peripheral wall 102 (periphery). 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 -X side, +X side, -Y side, and +Y side ends of the lower case 100, 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, with side wall W22 being the furthest to the +X side. Brackets 121 and 122 are provided on side walls W21 and W23, respectively. Discharge valves 151 and 152 are provided on side wall W22. Side wall W22 is connected to side walls W3 and W4 via side walls W21 and W23, respectively. The opposite ends (-X side) of side walls W3 and W4 are connected to each other via side wall W1, which extends in the Y direction. Brackets 131 and 132 are provided on side walls W3 and W4, respectively. Brackets 111 and 112 are provided on side wall W1. Each of side walls W1 to W4 rises from the periphery of the bottom wall 101 toward the +Z side. The internal space of the lower case 100 is enclosed by side walls W1 to W4. The energy storage device B is connected to, for example, the vehicle body (e.g., floor panel) by fastening brackets 111, 112, 121, 122, 131, and 132 to, for example, the floor member of the vehicle.

[0014] The bottom wall 101 is provided with partition walls 103 and 104 extending in the Y direction. Each of the partition walls 103 and 104 may be fastened to the bottom wall 101. Partition wall 104 is located on the +X side of partition wall 103. Each of the partition walls 103 and 104 stands upright on the +Z side from the bottom wall 101. Region R5 is a rectangular area located in the center of the lower case 100 and is partitioned by partition walls 103 and 104. Region R5 is the area where the wiring board 200 and energy storage stacks S1 to S6 (see Figure 2), which will be described later, are arranged. Region R5 is located between partition walls 103 and 104 (inside partition wall 103 and inside partition wall 104). Each of the partition walls 103 and 104 may be a cross frame.

[0015] In region R5, openings h1 are formed at the positions where each energy storage cell is placed. Each of the multiple openings h1 is positioned in the Z direction to face the valve 13 of the energy storage cell 10 (see Figure 3), which will be described later. Multiple openings h1 are arranged in the X direction to form rows of openings h1. A number of rows corresponding to the energy storage stack are formed in the bottom wall 101. The openings h1 are, for example, elongated holes that penetrate the bottom wall 101. However, the shape of the openings h1 can be changed as appropriate. The openings h1 are formed, for example, by punching.

[0016] In this embodiment, cover members 141 to 146 are provided in the region R5 of the bottom wall 101. As a result, all openings h1 formed in the bottom wall 101 are covered by the cover members 141 to 146. Each of the cover members 141 to 146 comprises a base material 105 that is elongated in the X direction and N lid portions 105a arranged in the X direction. In this embodiment, the number of energy storage cells included in one energy storage stack is also N. N is, for example, 20 or more and 50 or less. However, it is not limited to this, and N may be 2 or more and less than 20, or it may be more than 50.

[0017] The base material 105 may have an adhesive on one side (the adhesive surface). The base material 105 may be an adhesive tape such as a PP (polypropylene) tape. The N lid portions 105a are formed on the base material 105. In this embodiment, the lid portion 105a contains mica. The N lid portions 105a in the cover members 141, 142, 143, 144, 145, 146 are each formed to close an opening h1 located below the power storage stacks S1, S2, S3, S4, S5, S6 (see FIG. 2) described later. The size of the lid portion 105a is the same as or larger than the opening h1. For example, the N lid portions 105a may be formed on the base material 105 by attaching N mica foils to the adhesive surface of the base material 105. Alternatively, the N lid portions 105a may be formed on the base material 105 by forming N through holes in the base material 105 and providing mica foils in each of these through holes. The cover members 141 to 146 are attached to the upper surface (+Z side surface) of the bottom wall 101 through, for example, the adhesive surface of the base material 105. As described above, the portion of the lower case 100 facing the valve 13 (FIG. 3) of the power storage cell 10 contains mica. Mica is excellent in heat resistance and electrical insulation.

[0018] Regions R3 and R4 are provided on the -Y side and +Y side of region R5, respectively. Region R1 is provided outside the partition wall 103 (-X side). Region R2 is provided outside the partition wall 104 (+X side). Region R2 is the region where the battery circuit unit 30 (FIG. 2) is arranged. Region R2 is located at the +X side end of the lower case 100 and is partitioned by the partition wall 104 and the side wall W2. In this embodiment, each of the bottom wall 101, the peripheral wall 102, and the partition walls 103, 104 is formed of metal. However, these materials can be changed as appropriate.

[0019] Figure 2 is a top view of the inside of the lower case 100 (the inside of the energy storage device B) 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 case 100 and the upper cover 110. Each of the energy storage stacks S1 to S6 contains N energy storage cells 10 arranged in the X direction. Details of the configuration of each energy storage cell will be described later. The wiring board 200 has wiring patterns for the energy storage stacks S1 to S6. The battery circuit unit 30 includes circuits that are 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.

[0020] The cooling device 20 comprises 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 are connected in the order of port 20A, pipe 21A, pipe 22A, cooling pipe 23, pipe 22B, pipe 21B, and port 20B from the upstream side. Pipes 22A and 22B are connected via a plurality of coolers 22C (cooling plates) arranged in the X direction. Coolers 22C are placed between adjacent energy storage cells in the energy storage stacks S1 to S6. These adjacent energy storage cells are cooled by a refrigerant flowing through a channel formed inside the cooler 22C. The cooler 22C has a channel that communicates with each of the pipes 22A and 22B. The cooling pipe 23 is configured to cool the battery circuit unit 30.

[0021] Referring to FIGS. 1 and 2, ports 20A and 20B are provided on the side wall W1. Port 20B is located on the +Y side of port 20A. Pipes 21A and 21B are arranged in region R1. Pipes 22A and 22B are arranged in regions R3 and R4, respectively. Cooling pipe 23 is arranged in region R2. A plurality of coolers 22C are arranged in region R5. The refrigerant supplied from port 20A to pipe 21A flows in pipe 21A toward the -Y side. The refrigerant flowing from pipe 21A into pipe 22A flows in pipe 22A toward the +X side toward the cooling pipe 23 while also flowing into the flow paths of each of the plurality of coolers 22C. The refrigerant flowing from pipe 22A into cooler 22C flows toward the +Y side toward pipe 22B while cooling the power storage stacks S1 to S6. Further, the refrigerant flowing from pipe 22A into cooling pipe 23 flows toward the +Y side toward pipe 22B while cooling the battery circuit unit 30. The refrigerant flowing into pipe 22B from cooler 22C or cooling pipe 23 flows in pipe 22B toward the -X side toward pipe 21B. Thereafter, the refrigerant flows in pipe 21B toward the -Y side and flows out from port 20B. The refrigerant may be a liquid (such as water, oil, antifreeze, etc.) or a gas.

[0022] In this embodiment, a wiring board 200 is arranged on the +Z side of the bottom wall 101, and power storage stacks S1 to S6 are further arranged on the +Z side of the wiring board 200.

[0023] FIGS. 3 and 4 are end views of the power storage device B taken along lines III-III and IV-IV in FIG. 2, respectively. Also, a perspective view of the power storage cell 10 is shown on the left side of FIG. 3.

[0024] As shown in the perspective view on the left side of Figure 3, the energy storage cell 10 comprises a case 10a and an electrode body 10b housed in the case 10a. The case 10a is a rectangular case in the shape of a rectangular parallelepiped. The electrode body 10b may include one or more windings (for example, two windings). The windings have a structure in which, for example, a positive electrode sheet and a negative electrode sheet are wound with a separator in between. Each of the positive electrode sheet and the negative electrode sheet includes an electrode foil and an active material layer. The energy storage 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-type lithium-ion battery is used as the energy storage cell 10. The case 10a houses the electrolyte together with the electrode body 10b. The type of secondary battery is arbitrary, and for example, it may be an all-solid-state secondary battery. A laminate (for example, a laminate in which a positive electrode sheet and a negative electrode sheet are laminated with a separator in between) may be used instead of windings.

[0025] The energy storage cell 10 has electrode terminals 11 and 12 and a valve 13 on the same plane. Specifically, the electrode terminals 11 and 12 and the valve 13 are provided on a surface F10 of the case 10a. Surface F10 corresponds to one end face of the energy storage cell 10 in the height direction (Z direction). The valve 13 functions as an exhaust valve. The case 10a is basically maintained in a sealed state. However, if the pressure inside the case 10a exceeds a first reference value, the valve 13 opens to reduce the pressure inside the case 10a. Also, the electrode terminals 11 and 12 are electrically connected to the positive electrode sheet and negative electrode sheet of the electrode body 10b, respectively, and function as positive electrode terminals and negative electrode terminals. The parts of the case 10a surrounding the electrode terminals 11 and 12 may be formed of an insulating material, and the other parts may be formed of metal. However, the material of the case 10a is arbitrary and not limited to this.

[0026] In this embodiment, each energy cell included in the energy storage stacks S1 to S6 has the same configuration (the configuration shown in Figure 3). By forming the energy storage stacks S1 to S6 using a common energy storage cell 10, the manufacturing of the energy storage device B becomes easier and manufacturing costs can be reduced. However, this is not limited to this, and each energy storage stack may include multiple types of energy storage cells. Also, the number of energy storage stacks can be changed as appropriate. The number of energy storage stacks may be one or more.

[0027] Each energy cell in the energy storage stack S1 to S6 is electrically connected by the wiring pattern on the wiring board 200. The wiring board 200 is, for example, a panel on which a wiring pattern is formed. An example of the wiring pattern on the wiring board 200 is shown at the bottom of Figure 2.

[0028] Specifically, the wiring board 200 comprises 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 formed of, for example, resin.

[0029] Each of the multiple conductor members 211 electrically connects the energy cells included in the energy storage stack S1. Each of the multiple conductor members 212 electrically connects the energy cells included in the energy storage stack S2. Each of the multiple conductor members 213 electrically connects the energy cells included in the energy storage stack S3. Each of the multiple conductor members 214 electrically connects the energy cells included in the energy storage stack S4. Each of the multiple conductor members 215 electrically connects the energy cells included in the energy storage stack S5. Each of the multiple conductor members 216 electrically connects the energy cells included in the energy storage stack S6.

[0030] Conductor member 221 electrically connects energy storage stacks S1 and S2. Conductor member 222 electrically connects energy storage stacks S3 and S4. Conductor member 223 electrically connects energy storage stacks S5 and S6. Conductor members 231, 232, 233, 234, 235, and 236 electrically connect energy storage stacks S1, S2, S3, S4, S5, and S6 to the battery circuit unit 30, respectively.

[0031] In this embodiment, the wiring pattern of the wiring board 200 is formed by the above-described conductor members. Each of the conductor members 211-216, 221-223, and 231-236 is, for example, a metal plate-shaped member. Each of the conductor members 221-223 may be a U-shaped plate-shaped member. Each conductor member may also be a busbar. In this embodiment, each conductor member is fixed in a recess formed in the surface (+Z side) of the insulating substrate 201. The lower part of each conductor member is embedded in the insulating substrate 201. However, it is not essential that recesses (steps) for each conductor member be formed on the surface of the insulating substrate 201. Each conductor member may be joined to a flat surface of the insulating substrate 201. Furthermore, the material and shape of each conductor member are arbitrary.

[0032] The wiring board 200 is electrically connected to the battery circuit unit 30. As shown in Figure 2, the battery circuit unit 30 includes a total positive terminal 31, a total negative terminal 32, a J / B 33, a fuse 34, and wires L1 to L4. The total positive terminal 31 is located at the positive terminal end of the entire energy storage stack S1 to S6 (all energy storage cells). The total negative terminal 32 is located at the negative terminal end of the entire energy storage stack 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. A fuse 34 is provided on wire L2. Conductor member 236 is connected to the total positive terminal 31. Wire L3 electrically connects the total positive terminal 31 and the J / B 33. Conductor member 231 is connected to the total negative terminal 32. The wire L4 electrically connects the total negative terminal 32 to J / B33. J / B33 houses various electrical devices. J / B33 may include at least one of a relay, fuse, resistor, current sensor, and connector (e.g., a connector to an onboard charger). The battery circuit unit 30 may further include at least one of a BMS (Battery Management System) and an ECU (Electronic Control Unit).

[0033] An opening may be formed in the partition wall 104 for passing the conductor members 231 to 236 through. Alternatively, a wire (e.g., a cable) connected to the wiring board 200 may be connected to the battery circuit unit 30 by passing over the partition wall 104. Note that partition walls 103 and 104 are not essential components. At least one of partition walls 103 and 104 may be omitted.

[0034] Each of the energy storage stacks S1 to S6 contains the same number of energy storage cells, and the cells are arranged so that their positions are aligned. As a result, six energy storage cells 10 aligned in the Y direction form a row (a row in the Y direction). These rows are then aligned in the X direction. 6 × N energy storage cells 10 are arranged in a matrix with 6 rows in the Y direction and N rows in the X direction. In the wiring pattern shown in Figure 2, multiple parallel connections are connected in series. N energy storage cells 10 are arranged so that the positional relationship between the electrode terminals 11 (positive terminal) and electrode terminals 12 (negative terminal) is reversed every two cells. Each of the conductor members 211 to 216 connects two energy storage cells in parallel in the corresponding energy storage stack, and the resulting parallel connections (multiple energy storage cells connected in parallel) are connected in series. The connection configuration of the multiple energy storage cells can be changed as appropriate. For example, the number of energy storage cells connected in parallel may be three or more, not just two. Alternatively, all energy storage cells may be connected in series without forming parallel connections.

[0035] In the insulating substrate 201 of the wiring board 200, openings h2, as shown in Figure 3, are formed at the same positions as openings h1 (Figure 1) in the XY plane. Each of the same number of openings h2 (6 × N) as openings h1 faces the valve 13 of the energy storage cell 10 in the Z direction. Openings h2 are, for example, elongated holes that penetrate the insulating substrate 201. Openings h2 have larger dimensions than openings h1 (Figure 1) in the XY plane. In the XY plane, openings h1 are located inside openings h2. As shown in Figure 3, each opening h2 is connected to opening h1 via a cover portion 105a. Openings h2 are formed, for example, by punching.

[0036] In the manufacturing of the energy storage device B, for example, after installing the wiring board 200 inside the lower case 100, the energy storage stacks S1 to S6 are mounted on the wiring board 200 with the surface F10 of each energy storage cell facing downwards in the vertical direction. Then, the battery circuit unit 30 is connected to the wiring board 200, and the cooling device 20 is installed inside the lower case 100. As a result, the inside of the lower case 100 is in the state shown in Figure 2. Of the cooling device 20, the cooler 22C may be installed inside the lower case 100 together with the energy storage stacks S1 to S6. After that, the remaining part of the cooling device 20 may be placed inside the lower case 100, and the pipes 22A and 22B may be connected to the cooler 22C. The wiring board 200 and the battery circuit unit 30 may each be fixed to the lower case 100 with an adhesive (for example, silicone adhesive).

[0037] As shown in Figures 3 and 4, the upper cover 110 is joined to the upper surface (+Z side) of each of the side walls W1 to W4 (only side walls W1 and W3 are shown in Figures 3 and 4) via adhesive 110b and further fastened with bolts 110a. The shear panel 120 is joined to the lower surface (-Z side) of each of the side walls W1 to W4 via adhesive 120b. Although omitted in Figure 3, the piping 22A shown in Figure 2 is located in the space V3 between the energy storage cell 10 located at the -Y end of the lower case 100 and the side wall W3. Also, although omitted in Figure 4, the piping 21A shown in Figure 2 is located in the space V1 between the partition wall 103 and the side wall W1 within the lower case 100.

[0038] An exhaust passage P1 is formed between the bottom wall 101 of the lower case 100 and the shear panel 120. Each of the side walls W1 to W4 is formed in a hollow shape. As shown in Figure 3, an exhaust passage P3 is formed inside side wall W3. Although not shown, exhaust passages are also formed inside side walls W2 and W4 in a manner similar to the exhaust passage P3 of side wall W3. These exhaust passages are in communication with each other. In addition, exhaust holes connected to discharge valves 151 and 152 (Figure 2) are formed in side wall W2. These exhaust holes are in communication with the exhaust passages.

[0039] When the internal pressure of the energy storage cell 10 exceeds a first reference value, valve 13 opens as shown in Figure 3. Then, the pressure and heat of the gas discharged from inside the energy storage cell 10 through valve 13 create a hole in the cover portion 105a facing valve 13. The gas discharged from the energy storage cell 10 flows into the exhaust passage P1 through this hole. Each of the discharge valves 151 and 152 shown in Figure 2 opens when the pressure in the exhaust passage exceeds a second reference value. The second reference value may be a pressure value lower than the first reference value. For example, check valves are used for each of the discharge valves 151 and 152. When at least one of the discharge valves 151 and 152 opens, the gas in each exhaust passage flows toward the opened discharge valve and is discharged to the outside of the energy storage device B through that valve. The thickness of the lid portion 105a provided on the lower case 100 (Figure 1) is set to a thickness such that a hole is created when the opposing valve 13 opens (for example, when the valve opens in a manner that causes ignition).

[0040] A mica layer 120a (for example, mica foil) is provided on the inner (+Z side) surface of the shear panel 120. The mica layer 120a may be provided so as to overlap all of the cover portions 105a in the XY plane. The mica layer 120a protects the shear panel 120 from substances (gas, electrolyte, debris, etc.) released from the energy storage cell 10 through the cover portions 105a.

[0041] As shown in Figure 4, in each energy storage stack, an intermediate member 40 is provided between two adjacent energy storage cells 10 in the X direction, and a terminal member 40a is provided on the outside of the energy storage cell 10 located at the end in the X direction.

[0042] The intermediate member 40 includes the cooler 22C shown in Figure 2, two insulating pads 41, and two shock absorbers 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 energy storage cell 10. The shock absorbers 42 are located at both ends of the intermediate member 40 in the Z direction and suppress the transmission of shock to the cooler 22C. Figure 4 shows only the +Z end of the intermediate member 40, but the -Z end has a similar structure.

[0043] The terminal member 40a includes the cooler 22C shown in Figure 2, an insulating pad 41, an insulating pad 41a, and two shock absorbers 42a (only one is shown). The terminal member 40a has basically the same structure as the intermediate member 40. However, in the terminal member 40a, one of the two insulating pads 41 in the intermediate member 40 is replaced with an insulating pad 41a that is formed thicker than the insulating pad 41. The insulating pad 41a is located outside the cooler 22C (on the partition wall 103 side). This makes it difficult for shocks to be transmitted from the outside to the energy storage section (energy storage stack S1~S6). The shock absorbers 42a are located at both ends of the terminal member 40a in the Z direction and suppress the transmission of shocks to the cooler 22C. Figure 4 shows only the +Z side end of the terminal member 40a, but the -Z side end has a similar structure. Figure 4 shows only the termination member 40a located between the energy storage cell 10 at the -X end and the partition wall 103, but the termination member 40a is also provided between the energy storage cell 10 at the +X end and the partition wall 104.

[0044] As shown in Figures 3 and 4, each energy storage cell housed in the lower case 100 has electrode terminals 11 and 12 on the -Z side (side of the wiring board 200). The electrode terminals 11 and 12 of each energy storage cell are connected to one of the conductive members of the wiring board 200 via a conductive adhesive 50. This configuration allows for easy connection between the electrode terminals of each energy storage cell and the conductive members of the wiring board 200. Furthermore, the conductivity and adhesive properties of the conductive adhesive 50 maintain the electrical connection between the two. Bonding with a conductive adhesive has a wide tolerance for misalignment.

[0045] Hereinafter, of the two energy storage cells 10 shown in Figure 4, the energy storage cell 10 located on the -X side (partition wall 103 side) will be referred to as "energy storage cell C1," and the energy storage cell 10 located on the +X side will be referred to as "energy storage cell C2." Energy storage cells C1 and C2 correspond to examples of the "first energy storage cell" and "second energy storage cell" as described herein.

[0046] Referring to Figure 4, the energy storage cells C1 and C2 are arranged in a direction (X direction) perpendicular to the vertical direction (Z direction). The electrode terminals 12 of energy storage cell C1 and the electrode terminals 12 of energy storage cell C2 are each connected to the same conductor member 211, facing vertically downward. The -Z side surface of the electrode terminals 12 of energy storage cell C1 (hereinafter referred to as the "first surface") is roughened, for example by etching. The -Z side surface of the electrode terminals 12 of energy storage cell C2 (hereinafter referred to as the "second surface") is also roughened, for example by etching. Furthermore, the surface of the conductor member 211 (+Z side surface), specifically the part PT1 (first part) to which the electrode terminals 12 of energy storage cell C1 are connected, and the part PT2 (second part) to which the electrode terminals 12 of energy storage cell C2 are connected, are also roughened, for example by etching. Part PT1 of the conductor member 211 is the part facing the electrode terminal 12 of the energy storage cell C1 in the Z direction. Part PT2 of the conductor member 211 is the part facing the electrode terminal 12 of the energy storage cell C2 in the Z direction. Each part that has undergone roughening treatment has a greater surface roughness than the parts that have not undergone roughening treatment.

[0047] The first surface of the electrode terminal 12 of energy storage cell C1 is connected to part PT1 of the conductor member 211 via a conductive adhesive 50 (more specifically, the first conductive adhesive 50a in Figure 4). The second surface of the electrode terminal 12 of energy storage cell C2 is connected to part PT2 of the conductor member 211 via a conductive adhesive 50 (more specifically, the second conductive adhesive 50b in Figure 4). By roughening each of parts PT1 and PT2 of the conductor member 211, the bonding strength between each part and the conductive adhesive 50 is improved. Parts PT1 and PT2 may be formed rough to the extent that an anchoring effect is exhibited. Furthermore, by roughening each of the first surface of the electrode terminal 12 of energy storage cell C1 and the second surface of the electrode terminal 12 of energy storage cell C2, the bonding strength between each of these first and second surfaces and the conductive adhesive 50 is improved. The first and second surfaces may be formed rough to the extent that an anchoring effect is exhibited.

[0048] The roughening treatment is not limited to etching. For example, fine irregularities may be formed on parts PT1 and PT2, and on the first and second surfaces, respectively, by plating or anodizing. Furthermore, different types of roughening treatments may be used for the electrode terminals of the energy storage cell 10 and the conductive members of the wiring board 200.

[0049] Figure 5 is a diagram illustrating the joint between the energy storage cell 10 and the wiring board 200. Figure 5 shows, as a representative example, the structure of the joint between one electrode terminal (electrode terminal 12) and one conductor member (conductor member 211), but other joints (specifically, the joint between the electrode terminal of the energy storage cell 10 and the conductor member of the wiring board 200) have a similar structure.

[0050] As shown in Figure 5, on the +Z side surface F21 of the conductor member 211, the portion (surface F21a) facing the electrode terminal 12 has fine irregularities formed by the roughening treatment described above. Surface F21a has a rougher surface than the surrounding area. Similarly, the -Z side surface F22 of the electrode terminal 12 also has fine irregularities formed by the roughening treatment described above. As shown in the enlarged view at the bottom of Figure 5, the conductive adhesive 50 solidifies (hardens) while penetrating into the fine irregularities formed on surfaces F21a and F22, respectively. 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 be formed to have similar surface roughness. Surface roughness can be expressed, for example, as arithmetic mean roughness (Ra). However, this is not limited to this, and the surface roughness of each surface F21a and F22 may also be compared by their maximum height (Rz).

[0051] The conductive adhesive 50 comprises a binder 51 and a plurality of filler particles 52 dispersed in the binder 51. The binder 51 includes, for example, a resin. Each of the plurality of filler particles 52 is conductive. The conductive adhesive 50 having this configuration has high responsiveness to displacement in the X direction, displacement in the Y direction, and vibration in the Z direction, as shown on the left side of Figure 5. This makes it easier to maintain the connection between the electrode terminals of the energy storage device B and the conductive members of the wiring board 200 even after the energy storage device B is mounted on the vehicle.

[0052] The binder 51 may contain at least one of epoxy resin, phenolic resin, acrylic resin, urethane resin, and silicone resin. Using an epoxy resin or phenolic resin as the binder 51 makes it easier to increase the heat resistance of the conductive adhesive 50. Using an acrylic resin, urethane resin, or silicone resin as the binder 51 makes it easier to increase the conformability of the conductive adhesive 50. The multiple filler particles 52 may contain at least one of gold particles, silver particles, copper particles, nickel particles, and carbon particles. From the viewpoint of weight reduction, carbon particles are particularly preferred.

[0053] The conductive adhesive 50 is, for example, a heat-curing type conductive adhesive. However, it is not limited to this, and the conductive adhesive 50 may be a dry-curing type conductive adhesive or a two-component conductive adhesive (a conductive adhesive that hardens with a curing agent).

[0054] In mounting each energy storage cell to the wiring board 200, the conductive adhesive 50 before curing is applied to the joints of each conductor member of the wiring board 200 (for example, surface F21a shown in Figure 5), and then the energy storage stacks S1 to S6 are placed on the wiring board 200. The conductive adhesive 50 is then cured while pressure is applied evenly to each energy storage cell towards the wiring board 200 using, for example, the pressure equalizing device 600 shown in Figure 6. As a result, the electrode terminals of each energy storage cell and the conductor members of the wiring board 200 are connected via the conductive adhesive 50. Figure 6 is a diagram illustrating the method of connecting the energy storage cells 10 and the wiring board 200 according to this embodiment.

[0055] Referring to Figure 6, the pressure equalizer 600 comprises a lubrication device 610, piping 620, a check valve 620a, and a plurality of hydraulic cylinders 630. A hydraulic cylinder 630 is provided for each energy storage cell. More specifically, the hydraulic cylinders 630 are provided on the +Z side end face of each energy storage cell included in the energy storage stack S1 to S6. Each of these hydraulic cylinders 630 receives oil from a common lubrication device 610 and pressurizes the corresponding energy storage cell toward the -Z side (towards the wiring board 200). The lubrication device 610 and the plurality of hydraulic cylinders 630 are interconnected via a common piping 620. The lubrication device 610 supplies oil to each hydraulic cylinder 630 through the piping 620 until a predetermined hydraulic pressure is applied to each hydraulic cylinder 630. A check valve 620a provided in the piping 620 maintains the hydraulic pressure for each hydraulic cylinder 630 at a predetermined pressure. This maintains a state in which equal hydraulic pressure is applied to each hydraulic cylinder 630. In this state, the conductive adhesive 50 at each joint is cured. As a result, the distance in the Z direction between the electrode terminals of the energy storage cell and the conductive members of the wiring board 200 at each joint becomes uniform, and the thickness and density of the conductive adhesive 50 at each joint becomes uniform. With this configuration, it becomes easier to maintain the connection between the electrode terminals of the energy storage cell 10 and the conductive members of the wiring board 200 at each joint.

[0056] The various features of the energy storage device described above (each feature described in the embodiments and modifications) may be applied in any combination.

[0057] The use of the energy storage device is arbitrary. The energy storage device may be used in vehicles other than automobiles, mobile machinery (agricultural machinery, construction machinery, etc.), unmanned mobile devices, robots, or buildings.

[0058] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0059] 10 Energy storage cell, 11,12 Electrode terminals, 13 Valve, 22C Cooler, 50 Conductive adhesive, 100 Lower case, 101 Bottom wall, 102 Peripheral wall, 110 Upper cover, 120 Shear panel, 200 Wiring board, 201 Insulating substrate, 211~216 Conductor components, B Energy storage device, P1 Exhaust passage, S1~S6 Energy storage stack.

Claims

1. An energy storage device comprising a first energy storage cell, a second energy storage cell, and a conductive member, Each of the first and second energy storage cells has electrode terminals on the conductor member side, An energy storage device in which the electrode terminals of the first energy storage cell and the electrode terminals of the second energy storage cell are each connected to the conductor member via a conductive adhesive.

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

3. The aforementioned energy storage device further comprises an upper cover, a lower case, a share panel, a wiring board, and a cooler. The first energy storage cell, the second energy storage cell, and the wiring board are housed between the lower case and the upper cover. The wiring board has a wiring pattern formed by a plurality of conductor members, including the conductor member. The cooler is positioned between the first energy storage cell and the second energy storage cell. Each of the first and second energy storage cells further has an exhaust valve on the side on which the electrode terminals are provided. The energy storage device according to claim 2, wherein an exhaust passage is formed between the lower case and the shear panel.

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

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

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