Energy storage device

Abstract

To provide an energy storage device that can prevent waste from an energy storage cell from coming into contact with the safety valve of an adjacent energy storage cell. [Solution] The energy storage device 10 comprises a plurality of energy storage cells 100, a bottom wall 212, a panel member 230 that defines a smoke exhaust path S together with the bottom wall 212, and a protective member 500. A safety valve SV is provided on the lower surface of each energy storage cell 100. The bottom wall 212 has a plurality of through holes 212h. The protective member 500 includes a plurality of cylindrical portions 510 that protrude from each through hole 212h toward the panel member 230.

Description

Technical Field

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

Background Art

[0002] For example, Japanese Patent Publication No. 2024-501935 discloses an electrical device including a plurality of battery cells, a first housing that houses the plurality of battery cells, a second housing that houses the first housing, and a separation member provided in the second housing. The separation member supports the first housing at a position above the bottom surface of the second housing. A collection cavity is formed below the separation member in the second housing. A third fragile region is provided on the lower surface of the housing of the battery cell, a pressure release region is provided on the bottom surface of the first housing, and a second fragile region is provided on the separation member. The second fragile region is made of a material having a lower melting point than the regions of the separation member other than the second fragile region. Exhaust discharged from the battery cell through the third fragile region of the battery cell flows into the collection cavity formed below the separation member through the pressure release region and the second fragile region.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the electrical device described in Japanese Patent Publication No. 2024-501935, there is a concern that the gas contained in the exhaust discharged from one battery cell may contact the lower surface of the battery cell adjacent to the one power storage cell.

[0005] An object of the present disclosure is to provide a power storage device capable of suppressing contact between exhaust from a power storage cell and a safety valve of an adjacent power storage cell.

Means for Solving the Problems

[0006] A power storage device according to one aspect of the present disclosure comprises a plurality of power storage cells arranged in one direction, a bottom wall positioned below the plurality of power storage cells, a panel member provided below the bottom wall and together with the bottom wall defining a smoke exhaust path, and a protective member provided on the bottom wall, wherein each of the plurality of power storage cells has a safety valve on its lower surface, the bottom wall has a plurality of through holes, each positioned opposite to each of the safety valves, and the protective member includes a plurality of cylindrical portions each protruding toward the panel member from each of the plurality of through holes. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide an energy storage device that can prevent waste from an energy storage cell from coming into contact with the safety valve of an adjacent energy storage cell. [Brief explanation of the drawing]

[0008] [Figure 1] This figure schematically shows a vehicle equipped with an energy storage device according to one embodiment of the present disclosure. [Figure 2] This is a schematic perspective view of an energy storage device. [Figure 3] This is a schematic plan view showing the power storage device with the upper cover removed. [Figure 4] Figure 3 shows a cross-sectional view along line IV-IV. [Figure 5] Figure 3 is a cross-sectional view along the VV line. [Figure 6] This is a schematic perspective view showing the protective component. [Figure 7] This is a schematic cross-sectional view of the protective member. [Figure 8] This is a schematic cross-sectional view showing a modified example of the protective member. [Figure 9] This is a schematic cross-sectional view showing a modified example of the protective member. [Figure 10] This is a perspective view illustrating a modified example of the protective component. [Figure 11]It is a perspective view schematically showing a modified example of a protective member. [Figure 12] It is a cross-sectional view of the protective member shown in FIG. 11. [Figure 13] It is a perspective view schematically showing a modified example of a protective member. [Figure 14] It is a cross-sectional view of the protective member shown in FIG. 13. [Figure 15] It is a cross-sectional view schematically showing the relationship between the protective member and the column element. [Figure 16] It is a plan view schematically showing the column element. [Figure 17] It is a cross-sectional view schematically showing the relationship between the protective member and the column element. [Figure 18] It is a plan view schematically showing the column element.

Mode for Carrying Out the Invention

[0009] Embodiments of the present disclosure will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are given the same numbers.

[0010] FIG. 1 is a diagram schematically showing a vehicle including a power storage device according to an embodiment of the present disclosure. FIG. 2 is a perspective view schematically showing the power storage device. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. FIG. 5 is a cross-sectional view taken along line V-V in FIG. 3.

[0011] As shown in FIG. 1, the vehicle 1 includes a vehicle body 2 and a power storage device 10. Examples of the vehicle 1 include a hybrid electric vehicle, a plug-in hybrid electric vehicle, and a battery electric vehicle.

[0012] As shown in FIG. 1, the vehicle body 2 includes a frame member 20. The frame member 20 is disposed at the bottom of the vehicle body 2. The frame member 20 is formed in a substantially rectangular prism shape surrounding the power storage device 10.

[0013] The power storage device 10 is attached to the frame member 20. As shown in FIGS. 1 to 5, the power storage device 10 includes six power storage stacks 11 to 16, a housing 200, devices 300, a device cooler 350, a refrigerant pipe 400, and a protection member 500. Note that the number of power storage stacks is not limited to six.

[0014] Each of the power storage stacks 11 to 16 is formed in a rectangular parallelepiped shape long in the first direction. As shown in FIG. 2, the six power storage stacks 11 to 16 are arranged so as to line up along a second direction orthogonal to both the first direction and the vertical direction. Each of the power storage stacks 11 to 16 includes a plurality of power storage cells 100 and a plurality of cooling plates 150.

[0015] The plurality of power storage cells 100 are arranged so as to line up along the first direction. As shown in FIG. 4, each power storage cell 100 has an electrode body 112, a cell case 114, and a pair of external terminals 116.

[0016] The electrode body 112 may be composed of a wound body in which a positive electrode sheet and a negative electrode sheet are wound via a separator, or may be composed of a laminated body in which a positive electrode sheet and a negative electrode sheet are laminated via a separator. The electrode body 112 is formed in a shape long in the second direction.

[0017] The cell case 114 houses the electrode body 112. The cell case 114 is formed in a rectangular parallelepiped shape. The cell case 114 is made of a metal such as aluminum. A safety valve SV is provided on the lower surface of the cell case 114.

[0018] A pair of external terminals 116 are provided on the upper surface of the cell case 114. The pair of external terminals 116 are provided at positions spaced apart from each other in the width direction of the cell case 114. Note that the width direction corresponds to the second direction.

[0019] As shown in Figures 4 and 5, each cooling plate 150 is positioned between a pair of adjacent energy storage cells 100 in the first direction. Each cooling plate 150 is formed in a long, flat shape in the second direction. Each cooling plate 150 has a flow path (not shown) through which a refrigerant flows along the second direction.

[0020] The housing 200 houses six energy storage stacks 11 to 16. As shown in Figures 4 and 5, the housing 200 includes a lower case 210, an upper cover 220, and a panel member 230.

[0021] The lower case 210 is open upwards. The lower case 210 may be made of a metal such as aluminum. The lower case 210 has a bottom wall 212, a peripheral wall 214, and a pair of partition walls 216.

[0022] The bottom wall 212 is located below each of the energy storage stacks 11-16. In this embodiment, the bottom wall 212 is formed in a hollow shape. The bottom wall 212 may be formed by extrusion molding. However, the bottom wall 212 may also be formed in a solid and flat shape. As shown in Figures 4 and 5, the bottom wall 212 has a plurality of through holes 212h. Each through hole 212h is located opposite the safety valve SV.

[0023] The peripheral wall 214 rises from the periphery of the bottom wall 212. The peripheral wall 214 has a shape that surrounds each of the energy storage stacks 11 to 16. The peripheral wall 214 may be formed in a hollow shape. The peripheral wall 214 has a front wall 214a and a pair of side walls 214b.

[0024] The front wall 214a is formed on one side (the left side in Figure 3) of each energy storage stack 11-16 in the first direction. The front wall 214a extends in the second direction. In this embodiment, one side in the first direction corresponds to the front side in the longitudinal direction of the vehicle.

[0025] The pair of side walls 214b are spaced apart from each other and face each other in the second direction. Each side wall 214b extends in the first direction. One end (front end) of each side wall 214b in the first direction is connected to the front wall 214a.

[0026] A pair of partition walls 216 divide the space enclosed by the bottom wall 212 and the perimeter wall 214 into a space in which each energy storage stack 11-16 is arranged and other spaces. The pair of partition walls 216 are spaced apart from each other in a first direction. Each partition wall 216 extends in a second direction. Each partition wall 216 may be formed in a hollow shape. The pair of partition walls 216 have the function of restraining each energy storage stack 11-16 from both sides in the first direction. As shown in Figure 3, the end of the partition wall 216 formed on one side (front side) in the first direction in the second direction is spaced apart from each side wall 214b. The end of the partition wall 216 formed on the other side (rear side) in the first direction in the second direction is connected to each side wall 214b.

[0027] The upper cover 220 is positioned above each of the energy storage stacks 11-16. The upper cover 220, together with the lower case 210, houses the six energy storage stacks 11-16. Specifically, the upper cover 220, together with the lower case 210, houses the six energy storage stacks 11-16 in a sealed state. The peripheral edge of the upper cover 220 is connected to the upper end of the peripheral wall 214 by bolts or the like via a sealing member.

[0028] The panel member 230 is located below the lower case 210. The panel member 230 has the function of protecting the bottom wall 212 of the lower case 210. The panel member 230 may be formed in a flat plate shape. The peripheral edge of the panel member 230 is connected to the lower surface of the lower case 210 via a sealing member.

[0029] As shown in Figures 4 and 5, a space S is formed between the panel member 230 and the bottom wall 212. Each space S functions as a smoke exhaust path (hereinafter referred to as "smoke exhaust path S"). The smoke exhaust path S is a path for discharging the gas discharged from the safety valve SV of the energy storage cell 100 to the outside of the housing 200.

[0030] As shown in Figures 3 and 5, a smoke exhaust duct section 218 is formed in the peripheral wall 214. The smoke exhaust duct section 218 extends upward from the bottom wall 212. The smoke exhaust duct section 218 guides the gas upward from the smoke exhaust path S. An explosion-proof valve 290 is provided at the downstream end of the smoke exhaust duct section 218. The explosion-proof valve 290 releases the pressure inside the housing 200. The explosion-proof valve 290 opens when the pressure inside the housing 200 exceeds a reference value. The explosion-proof valve 290 is a check valve. As shown in Figure 5, when gas is discharged from any of the energy storage cells 100, the gas spreads in the first direction through the smoke exhaust path S and is discharged outside the housing 200 through the smoke exhaust duct section 218 and the explosion-proof valve 290.

[0031] The equipment 300 is housed in the enclosure 200. As shown in Figure 3, the equipment 300 is located in the space formed between the partition wall 216 and the peripheral wall 214 on the other side of the lower case 210 in the first direction, i.e., the other side (rear side) in the first direction. The equipment 300 may include a junction box. The equipment 300 may include relays, control equipment, etc.

[0032] The equipment cooler 350 cools the equipment 300. As shown in Figures 3 and 5, the equipment cooler 350 is provided between the bottom wall 212 and the equipment 300. A thermally conductive adhesive 900 may be provided between the equipment cooler 350 and the bottom wall 212.

[0033] The refrigerant piping 400 is routed within the housing 200. The refrigerant piping 400 is connected to each cooling plate 150 and the equipment cooler 350. As shown in Figures 2 and 3, the front wall 214a of the peripheral wall 214 is provided with an inlet port 181 and an outlet port 182. The refrigerant piping 400 is connected to the inlet port 181 and the outlet port 182. Therefore, the refrigerant (water, oil, etc.) supplied from the inlet port 181 flows through the refrigerant piping 400 to each cooling plate 150 and the equipment cooler 350, cools each energy storage cell 100 and equipment 300, and then flows out through the refrigerant piping 400 from the outlet port 182.

[0034] As shown in Figure 3, the refrigerant piping 400 includes an upstream pipe 410 and a downstream pipe 420.

[0035] The upstream end of the upstream piping 410 is connected to the inlet port 181. The downstream end of the upstream piping 410 is connected to one end of the equipment cooler 350 in the second direction. The upstream piping 410 is routed to pass between the front wall 214a and the partition wall 216 formed on one side in the first direction, and between the energy storage stack 11 and the side wall 214b located on one side in the second direction. The upstream piping 410 is connected to one end of each cooling plate 150 in the second direction.

[0036] The upstream end of the downstream piping 420 is connected to the other end of the equipment cooler 350 in the second direction. The downstream end of the downstream piping 420 is connected to the outlet port 182. The downstream piping 420 is routed to pass between the front wall 214a and the partition wall 216 formed on one side in the first direction, and between the energy storage stack 16 located on the other side in the second direction and the side wall 214b. The downstream piping 420 is connected to the other end of each cooling plate 150 in the second direction.

[0037] The protective member 500 is provided on the bottom wall 212. The protective member 500 has the function of protecting each energy storage cell 100 from gas discharged from the safety valve SV. The protective member 500 is made of, for example, synthetic resin. As shown in Figures 4 to 7, the protective member 500 has a plurality of cylindrical portions 510, a plurality of flanges 520, and a plurality of closing portions 530.

[0038] Each cylindrical portion 510 protrudes toward the panel member 230 from each through hole 212h. The lower end portion 512 of the cylindrical portion 510 is separated upward from the panel member 230. In this embodiment, as shown in Figure 6, the cylindrical portion 510 is formed in a cylindrical shape. However, the cross-sectional shape of the cylindrical portion 510 is not particularly limited. For example, the cylindrical portion 510 may be formed in a rectangular cylindrical shape.

[0039] The flange 520 protrudes outward from the upper end of the cylindrical portion 510. The flange 520 may be formed in an annular shape. The outer shape of the flange 520 is larger than the outer shape of the through hole 212h. The flange 520 is in contact with the upper surface of the bottom wall 212. The flange 520 has the function of preventing the cylindrical portion 510 from falling from the bottom wall 212 toward the panel member 230.

[0040] The occlusion portion 530 blocks the inside of the cylindrical portion 510. As shown in Figure 7, the thickness of the occlusion portion 530 is less than the thickness of the cylindrical portion 510. The occlusion portion 530 is set to a strength that will cause it to rupture due to exhaust, including gas, discharged from the safety valve SV.

[0041] In the energy storage device 10 described above, if a discharge is made downward from the safety valve SV due to a short circuit or the like in any of the energy storage cells 100, the discharge will collide with the closure section 530. As a result, the closure section 530 will rupture, and the discharge will flow into the exhaust gas path S. Subsequently, the gas contained in the discharge will spread through the exhaust gas path S and be discharged from the housing 200 through the explosion-proof valve 290, as shown in Figure 5.

[0042] Here, as the gas that has flowed into the exhaust path S through the cylindrical section 510 spreads within the exhaust path S, as shown in Figures 4 and 5, the gas forms a swirling flow within the cylindrical section 510 located below the energy storage cell 100 adjacent to the energy storage cell 100 that discharged the exhaust (hereinafter referred to as the "adjacent energy storage cell"). As a result, the gas rising within the cylindrical section 510 prevents it from contacting the safety valve SV of the adjacent energy storage cell.

[0043] Furthermore, since the protective member 500 in this embodiment includes a blocking portion 530, the gas rising inside the cylindrical portion 510 located below the adjacent energy storage cell is effectively blocked by the blocking portion 530.

[0044] Modifications of the above embodiment will be described below.

[0045] <First variation> As shown in Figure 8, the closing portion 530 of the protective member 500 may have a central portion 532 and an edge portion 534.

[0046] The central portion 532 is formed to be thick. The thickness of the central portion 532 may be greater than the thickness of the cylindrical portion 510.

[0047] The edge portion 534 is formed around the central portion 532. The edge portion 534 connects the central portion 532 and the cylindrical portion 510. The thickness of the edge portion 534 is less than the thickness of the central portion 532. The thickness of the edge portion 534 is less than the thickness of the cylindrical portion 510.

[0048] In this embodiment, when waste is discharged from one energy storage cell 100, the edge portion 534 splits open, causing the central portion 532 to fall and the waste to flow into the exhaust path S.

[0049] <Second variation> As shown in Figure 9, the cross-sectional area of ​​the cylindrical portion 510 in a plane perpendicular to the vertical direction may gradually decrease as it approaches the panel member 230. For example, the cylindrical portion 510 has a shape that gradually decreases in diameter as it approaches the panel member 230.

[0050] <Third variation> As shown in Figure 10, the protective member 500 may include a connecting portion 540 that connects a pair of adjacent cylindrical portions 510 or a pair of flanges 520 in at least one of the first and second directions. In the example shown in Figure 10, the connecting portion 540 connects a pair of adjacent flanges 520.

[0051] <Fourth variation> As shown in Figures 11 and 12, the protective member 500 may include a projection 550 that protrudes outward in the radial direction of the cylindrical portion 510 from the outer surface of the cylindrical portion 510.

[0052] In this example, the cylindrical portion 510 has an arm portion 515. The arm portion 515 is formed between a pair of slits 510S provided in the cylindrical portion 510. Each slit 510S extends upward from the lower end portion 512 of the cylindrical portion 510. The arm portion 515 is elastically deformable such that its lower end is displaced radially in the cylindrical portion 510 relative to its upper end.

[0053] The projection 550 is provided on the outer surface of the lower end of the arm portion 515. The projection 550 is located below the bottom wall 212 and faces the lower surface of the bottom wall 212. The distance between the lower surface of the flange 520 and the upper surface of the projection 550 is set to be the same as or slightly greater than the thickness of the bottom wall 212.

[0054] In this example, by inserting the cylindrical portion 510 into the through hole 212h from above the bottom wall 212, the arm portion 515 deforms so that the protruding portion 550 moves radially inward. Then, when the protruding portion 550 reaches below the bottom wall 212, the arm portion 515 returns to its neutral position, and the bottom wall 212 is clamped between the flange 520 and the protruding portion 550.

[0055] <Fifth variation> As shown in Figures 13 and 14, the protective member 500 may include a protruding portion 550 and a plurality of legs 560.

[0056] In this example, the projection 550 has a shape that protrudes outward from the outer circumferential surface of the cylindrical portion 510. The projection 550 may also be formed in an annular shape. The projection 550 is provided on the outer circumferential surface of the intermediate portion of the cylindrical portion 510 in the vertical direction. The projection 550 faces the lower surface of the bottom wall 212.

[0057] Multiple legs 560 extend downward from the lower end 512 of the cylindrical portion 510. Each leg 560 is positioned at a distance from each other in the circumferential direction of the cylindrical portion 510. The distance between the lower end of each leg 560 and the upper surface of the projection 550 is set to be the same as or slightly less than the distance between the lower surface of the bottom wall 212 and the upper surface of the panel member 230.

[0058] <Sixth variation> As shown in Figures 15 and 16, the energy storage device 10 may include a column element 570. The column element 570 is positioned between the bottom wall 212 and the panel member 230. The column element 570 may be fixed to the upper surface of the panel member 230. As shown in Figure 15, the distance h2 between the upper end of the column element 570 and the lower surface of the bottom wall 212 is shorter than the distance h1 between the upper surface of the panel member 230 and the lower end 512 of the cylindrical portion 510. As shown in Figure 16, the column element 570 may be formed in a hexagonal prism shape in plan view.

[0059] In this embodiment, the gas contained in the exhaust from one energy storage cell 100 travels through the space between the column element 570 and the bottom wall 212 towards the explosion-proof valve 290, as indicated by the arrows in Figure 15.

[0060] <7th variation> As shown in Figures 17 and 18, the energy storage device 10 may include a column element 570. Note that Figure 17 shows a cross-section at the position corresponding to line XVII-XVII in Figure 18.

[0061] In this example, the cylindrical portion 510 is formed in a hexagonal prism shape. The lower end of the cylindrical portion 510 is in contact with the panel member 230. The lower part of the cylindrical portion 510 has a notch 513 for allowing gas to flow out of the cylindrical portion 510.

[0062] The column element 570 is positioned between the bottom wall 212 and the panel member 230. The column element 570 may be fixed to the upper surface of the panel member 230. The height of the column element 570 is less than the distance between the lower surface of the bottom wall 212 and the upper surface of the panel member 230.

[0063] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following embodiments.

[0064] [Aspect 1] Multiple energy storage cells arranged in one direction, A bottom wall positioned below the plurality of energy storage cells, A panel member provided below the bottom wall, which together with the bottom wall defines the smoke exhaust space, The bottom wall is provided with a protective member, A safety valve is provided on the lower surface of each of the aforementioned plurality of energy storage cells. The bottom wall has a plurality of through holes, each of which is provided in a position facing each of the safety valves. The protective member includes a plurality of cylindrical portions, each protruding toward the panel member from each of the plurality of through holes, in an energy storage device.

[0065] In this energy storage device, when waste discharged from one energy storage cell flows into the exhaust space through the cylindrical section, the gas contained in the waste forms a swirling flow within the cylindrical section located below the adjacent energy storage cell. As a result, the gas rising within the cylindrical section is prevented from reaching the safety valve of the adjacent energy storage cell.

[0066] [Aspect 2] The energy storage device according to embodiment 1, wherein the protective member further includes a closing portion that closes the inside of the cylindrical portion.

[0067] In this embodiment, the gas discharged from one energy storage cell causes the closure to rupture, allowing the gas to effectively flow into the exhaust space, while the gas rising from the exhaust space towards other energy storage cells within the cylindrical section is effectively blocked by the closure.

[0068] [Aspect 3] The energy storage device according to embodiment 1 or 2, wherein the cross-sectional area of ​​each cylindrical portion in a plane perpendicular to the vertical direction gradually decreases as it approaches the panel member.

[0069] In this embodiment, the inflow of gas into the cylindrical section from below is more reliably suppressed.

[0070] [Aspect 4] The energy storage device according to any one of embodiments 1 to 3, wherein the protective member includes a connecting portion that connects a pair of adjacent cylindrical portions in one direction to each other.

[0071] In this embodiment, handling of multiple cylindrical parts becomes easier.

[0072] [Aspect 5] The protective member includes a protruding portion that extends from the outer surface of the cylindrical portion, The energy storage device according to any one of embodiments 1 to 4, wherein the protruding portion is located below the bottom wall and faces the bottom wall.

[0073] In this embodiment, even when an external force (upward load) acts on the panel member from below, causing the panel member to come into contact with the cylindrical portion of the protective member, the protruding portion abuts the bottom wall from below, thus preventing the protective member from separating upward from the bottom wall. Therefore, collision of the protective member with the lower surface of the energy storage cell is suppressed.

[0074] [Aspect 6] The system further comprises column elements positioned between the bottom wall and the panel member, The energy storage device according to any one of embodiments 1 to 5, wherein the distance between the column element and the bottom wall is shorter than the distance between the panel member and the cylindrical portion.

[0075] In this embodiment, when an external force (upward load) acts on the panel member from below, the column element comes into contact with the bottom wall and the panel member before the panel member comes into contact with the cylindrical portion, thus preventing the protective member from detaching upward from the bottom wall. Therefore, collision of the protective member with the lower surface of the energy storage cell is suppressed.

[0076] It should be noted that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of this disclosure is defined by the claims rather than the description of the embodiments above, and includes all modifications within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0077] 1 Vehicle, 2 Vehicle body, 10 Energy storage device, 11-16 Energy storage stack, 20 Frame member, 100 Energy storage cell, 112 Electrode body, 114 Cell case, 116 External terminal, 200 Housing, 210 Lower case, 212 Bottom wall, 214 Peripheral wall, 216 Partition wall, 220 Upper cover, 230 Panel member, 300 Equipment, 350 Equipment cooler, 400 Refrigerant piping, 410 Upstream piping, 420 Downstream piping, 500 Protective member, 510 Cylindrical section, 512 Lower end, 510S Slit, 513 Notch, 515 Arm section, 520 Flange, 530 Closure section, 532 Center section, 534 Edge section, 540 Connecting section, 550 Protruding section, 560 Leg section, 570 Column element, 900 thermal conductive adhesive, S space (smoke exhaust path), SV safety valve.

Claims

1. Multiple energy storage cells arranged in one direction, A bottom wall positioned below the plurality of energy storage cells, A panel member provided below the bottom wall, which together with the bottom wall defines the smoke exhaust path, The bottom wall is provided with a protective member, A safety valve is provided on the lower surface of each of the aforementioned plurality of energy storage cells. The bottom wall has a plurality of through holes, each of which is provided in a position facing each of the safety valves. The protective member includes a plurality of cylindrical portions, each protruding toward the panel member from each of the plurality of through holes, in an energy storage device.

2. The energy storage device according to claim 1, wherein the protective member further includes a closing portion that closes the inside of the cylindrical portion.

3. The energy storage device according to claim 1, wherein the cross-sectional area of ​​each cylindrical portion in a plane perpendicular to the vertical direction gradually decreases as it approaches the panel member.

4. The energy storage device according to any one of claims 1 to 3, wherein the protective member includes a connecting portion that connects a pair of cylindrical portions adjacent to each other in one direction.

5. The protective member includes a protruding portion that extends from the outer surface of the cylindrical portion, The energy storage device according to claim 1, wherein the protruding portion is located below the bottom wall and faces the bottom wall.

6. The system further comprises column elements positioned between the bottom wall and the panel member, The energy storage device according to claim 1, wherein the distance between the column element and the bottom wall is shorter than the distance between the panel member and the cylindrical portion.

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