Electric storage cell

Abstract

To reduce uneven distribution of an electrolyte in a vertical power storage cell.SOLUTION: The power storage cell includes a cell case, a wound electrode body, and an electrolyte solution. The cell case houses the wound electrode body and the electrolytic solution. The wound electrode body includes a positive electrode sheet, a separator sheet, and a negative electrode sheet. In the direction of the axis of winding, the wound electrode assembly has a first end portion and a second end portion. The first end portion faces the top wall. The second end is located opposite to the first end. At both the first end and the second end, the separator sheet extends outward beyond the negative electrode sheet. At the first end, the separator sheet has a first protruding length. At the second end, the separator sheet has a second protruding length. The first protruding length is longer than the second protruding length.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open Publication No. 2016-207516 (Patent Document 1) discloses a wound electrode body housed vertically in a case body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-207516 Summary of the Invention [Problem to be solved by the invention]

[0004] Energy storage cells including a wound electrode body can be broadly divided into, for example, a "vertical type" and a "horizontal type." In the vertical type, the wound electrode body is housed in the case body so that the opening surface of the case body and the winding axis direction of the wound electrode body are perpendicular to each other. The "winding axis direction" refers to the direction in which the winding axis extends. In the horizontal type, the wound electrode body is housed in the case body so that the opening surface of the case body and the winding axis direction of the wound electrode body are parallel to each other. The wound electrode body is impregnated with an electrolyte.

[0005] An object of the present disclosure is to reduce uneven distribution of electrolyte in a vertical energy storage cell. [Means for solving the problem]

[0006] The technical configuration and effects of the present disclosure will be described below. However, the mechanism of action in this specification includes speculation. The mechanism of action does not limit the technical scope of the present disclosure.

[0007] 1. The energy storage cell includes a cell case, a wound electrode assembly, and an electrolyte. The cell case houses the wound electrode assembly and the electrolyte. The wound electrode assembly is impregnated with the electrolyte. The cell case includes a top wall, a peripheral wall, and a bottom wall. The top wall faces the bottom wall. The peripheral wall connects the top wall and the bottom wall. The wound electrode body includes a positive electrode sheet, a separator sheet, and a negative electrode sheet, and the winding axis direction of the wound electrode body is aligned along the direction from the bottom wall to the top wall. The wound electrode body has a first end and a second end in the winding axis direction. The first end faces the top wall. The second end is located opposite the first end. At both the first end and the second end, the separator sheet extends outward beyond the negative electrode sheet. At the first end, the separator sheet has a first protrusion length. At the second end, the separator sheet has a second protrusion length. The first protrusion length and the second protrusion length are lengths by which the separator sheet protrudes from the negative electrode sheet in the winding axis direction. The first protrusion length is longer than the second protrusion length.

[0008] The wound electrode assembly includes a positive electrode sheet, a separator sheet, and a negative electrode sheet. Each sheet is strip-shaped (a long rectangle). Each sheet has a length direction and a width direction. The "length direction" is the direction parallel to the long sides of the rectangle. The "width direction" is the direction parallel to the short sides of the rectangle. Each sheet has a different width (width dimension). That is, the separator sheet has the largest width, and the positive electrode sheet has the smallest width. The negative electrode sheet has a width intermediate between the two. In the vertical type, the winding axis direction is parallel to the width direction. Therefore, the separator sheet protrudes furthest outward in the winding axis direction. At the upper end (first end) of the wound electrode assembly, the protrusion length (extension) of the separator sheet from the negative electrode sheet is the first protrusion length. At the lower end (second end) of the wound electrode assembly, the protrusion length of the separator sheet from the negative electrode sheet is the second protrusion length. Conventionally, the first protrusion length is equal to the second protrusion length.

[0009] In a wound electrode body, the electrolyte tends to overflow from both ends in the direction of the winding axis. This is because there are gaps between the sheets at both ends. The separator sheet is porous. The separator sheet has pores. The separator sheet can absorb the electrolyte by capillary action. When the separator sheet protruding from the lower end comes into contact with the electrolyte overflowing from the lower end (second end), it is expected that the electrolyte will be absorbed by the separator sheet.

[0010] The electrolyte solution spilling out from the upper end (first end) of the wound electrode body flows down along the outer surface of the wound electrode body to the lower end. At the lower end, the electrolyte solution can be absorbed by the separator sheet. However, the speed at which the electrolyte solution is absorbed is slow. If the frequency of the electrolyte solution spilling out from the upper end increases, the absorption of the electrolyte solution cannot keep up. As a result, it is thought that a bias in the distribution of the electrolyte solution in the wound electrode body may occur.

[0011] In the present disclosure, the first protrusion length (upper end side) is longer than the second protrusion length (lower end side). At the upper end, the long protruding separator sheet is expected to block the overflow of the electrolyte. By reducing the frequency of the electrolyte overflowing from the upper end, it is expected that the uneven distribution of the electrolyte will be reduced.

[0012] 2. In the energy storage cell described in the above item "1," the ratio of the first protrusion length to the second protrusion length may be, for example, 1.5 to 5. This is because there is a possibility that uneven distribution of the electrolyte solution may be reduced.

[0013] 3. In the storage cell according to the above item "1" or "2," the difference between the first protrusion length and the second protrusion length may be, for example, 1 to 5 mm. This is because there is a possibility that uneven distribution of the electrolyte solution may be reduced.

[0014] 4. In the energy storage cell according to any one of the above items "1" to "3," the first protrusion length may be, for example, 2 to 5 mm. The second protrusion length may be, for example, 0.5 to 1.5 mm. This is because there is a possibility that uneven distribution of the electrolyte solution may be reduced.

[0015] 5. In the energy storage cell according to any one of the above items "1" to "4," the cell case may include, for example, a case body and a lid. The case body includes a peripheral wall and a bottom wall. The peripheral wall stands upright from the bottom wall. The case body has an opening surface. The opening surface faces the bottom wall. The lid includes a top wall. The lid closes the opening surface.

[0016] Hereinafter, an embodiment of the present disclosure (hereinafter may be abbreviated as "the present embodiment") will be described. However, the present embodiment does not limit the technical scope of the present disclosure. The present embodiment is illustrative in all respects. The present embodiment is non-restrictive. The technical scope of the present disclosure encompasses all modifications within the meaning and scope equivalent to the claims. For example, it is also intended from the beginning that any configuration may be extracted from the present embodiment and arbitrarily combined. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic perspective view of a storage cell according to this embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the storage cell according to this embodiment. [Figure 3] FIG. 3 is a schematic cross-sectional view of the energy storage cell of this embodiment. [Figure 4] FIG. 4 is a conceptual diagram showing the layered structure of the wound electrode body. DETAILED DESCRIPTION OF THE INVENTION

[0018] In this embodiment, geometric terms (e.g., "parallel," "perpendicular," and the like) should not be interpreted in a strict sense. For example, "parallel" may deviate slightly from the strict meaning of "parallel." Geometric terms may include, for example, tolerances, errors, and the like in design, work, and manufacturing. The dimensional relationships in each drawing may not match the actual dimensional relationships. To facilitate reader understanding, the dimensional relationships (length, width, thickness, and the like) in each drawing may be changed. Furthermore, some components may be omitted. In each drawing, functionally identical or equivalent components may be designated by the same reference numerals.

[0019] Numerical ranges such as "m~n%" include the upper and lower limits unless otherwise specified. In other words, "m~n%" indicates a numerical range of "m% or more and n% or less." Furthermore, "m% or more and n% or less" includes "more than m% and less than n%." "Equal to or more" and "equal to or less" are expressed by the inequality sign "≦" with an equal sign. "More than" and "less than" are expressed by the inequality sign "<" without an equal sign.

[0020] <Energy storage cell> Fig. 1 is a schematic perspective view of a storage cell in this embodiment. Fig. 2 is an exploded perspective view of the storage cell in this embodiment. Fig. 3 is a schematic cross-sectional view of the storage cell in this embodiment. The storage cell 1 includes a cell case 200, a wound electrode body 100, and an electrolyte (not shown).

[0021] <Cell Case> The cell case 200 houses the wound electrode body 100 and the electrolyte. The cell case 200 is sealed. The cell case 200 may be made of, for example, metal. The cell case 200 may contain, for example, Al. The cell case 200 may include, for example, a case body 210 and a lid 220.

[0022] The case body 210 includes a bottom wall 212 and a peripheral wall 214 (see FIG. 3). That is, the cell case 200 includes the bottom wall 212 and the peripheral wall 214. The bottom wall 212 may be, for example, flat. In a plan view, the bottom wall 212 may be rectangular. "Plan view" refers to viewing an object with a line of sight parallel to the thickness direction of the object. That is, a plan view of the bottom wall 212 refers to viewing the bottom wall 212 from the Z-axis direction. The peripheral wall 214 stands upright from the bottom wall 212. The peripheral wall 214 may be, for example, rectangular tubular. The peripheral wall 214 connects the top wall 222 and the bottom wall 212.

[0023] The dimension of the peripheral wall 214 in the width direction (X-axis direction) of the case body 210 may be larger than the dimension of the peripheral wall 214 in the thickness direction (Y-axis direction) of the case body 210, for example. The dimension of the peripheral wall 214 in the height direction (Z-axis direction) of the case body 210 may be larger than the dimension of the peripheral wall 214 in the thickness direction. The case body 210 has an opening surface 211 (see FIG. 2). The opening surface 211 faces the bottom wall 212. The opening surface 211 is surrounded by the peripheral wall 214.

[0024] The lid 220 includes a top wall 222. That is, the cell casing 200 includes the top wall 222. The lid 220 closes the opening surface 211. For example, the top wall 222 may be joined to the peripheral wall 214 by laser welding. The top wall 222 may be, for example, flat. The top wall 222 faces the bottom wall 212. For example, a pressure release valve 222a, a liquid injection hole 222b, a sealing member 222c, a through-hole 222d, etc. may be provided in the top wall 222.

[0025] The height direction (Z-axis direction) of the energy storage cell 1 is the direction from the bottom wall 212 toward the top wall 222. The height direction may be along the vertical direction. The height direction may be parallel to the vertical direction. The energy storage cell 1 is of a vertical type. In a vertical type, the winding axis direction of the wound electrode body 100 is along the height direction. The angle (acute angle) between the winding axis direction and the height direction may be, for example, 30 degrees or less, 20 degrees or less, 10 degrees or less, or 5 degrees or less. The winding axis direction may be parallel to the height direction.

[0026] <Wound electrode body> FIG. 4 is a conceptual diagram showing the layer structure of a wound electrode body. The wound electrode body 100 includes a positive electrode sheet 10, a separator sheet 30, and a negative electrode sheet 20. The positive electrode sheet 10, the separator sheet 30, and the negative electrode sheet 20 are layered in this order to form a laminate. The layer stacking direction corresponds to the Y-axis direction in FIG. 4. That is, in the normal direction (Y-axis direction) of FIG. 4, the positive electrode sheet 10 is located at the back end. The negative electrode sheet 20 is located at the front end. The separator sheet 30 is interposed between the positive electrode sheet 10 and the negative electrode sheet 20. The wound electrode body 100 is formed by spirally winding the laminate. The winding axis direction corresponds to the Z-axis direction in FIG. 4. The Z-axis direction also corresponds to the width direction of each sheet. The wound electrode body 100 may have a flattened outer shape (see FIG. 2). For example, the cylindrical wound electrode body 100 may be crushed in the diameter direction to be formed into a flat shape.

[0027] The wound electrode body 100 may include two or more separator sheets 30. The wound electrode body 100 may include, for example, a first separator sheet, a positive electrode sheet 10, a second separator sheet, and a negative electrode sheet 20 in this order. The wound electrode body 100 may include, for example, a positive electrode sheet 10, a first separator sheet, a negative electrode sheet 20, and a second separator sheet in this order.

[0028] Each sheet has a strip-like planar shape. That is, each sheet has a length direction and a width direction. In FIG. 4, the length direction corresponds to the X-axis direction. The width direction corresponds to the Z-axis direction. Furthermore, the width direction is along the winding axis direction. In the winding axis direction (Z-axis direction), the wound electrode body 100 has a first end E1 and a second end E2. In the winding axis direction (Z-axis direction), the second end E2 is located on the opposite side of the first end E1. The first end E1 faces the top wall 222. The second end E2 faces the bottom wall 212. At both the first end E1 and the second end E2, the separator sheet 30 extends outward beyond the negative electrode sheet 20. At the first end E1, the separator sheet 30 has a first protrusion length ΔW1. The first protrusion length ΔW1 can be expressed as the distance between the leading end of the separator sheet 30 and the leading end of the negative electrode sheet 20 in the winding axis direction (width direction). At the second end E2, the separator sheet 30 has a second protrusion length ΔW2. The second protrusion length ΔW2 can be expressed as the distance between the front end of the separator sheet 30 and the front end of the negative electrode sheet 20 in the width direction.

[0029] The first protrusion length ΔW1 is greater than the second protrusion length ΔW2. This allows the protrusion of the separator sheet 30 on the first end E1 side to function as a dam for the electrolyte. This reduces the overflow of the electrolyte from the first end E1 side. For example, a dam for the electrolyte may be formed at the first end E1.

[0030] When the wound electrode body 100 includes two separator sheets 30, at least one of the first separator sheet and the second separator sheet satisfies the relationship "ΔW2<ΔW1." For example, both the first separator sheet and the second separator sheet may satisfy the relationship "ΔW2<ΔW1." For example, the first separator sheet may satisfy the relationship "ΔW2<ΔW1," and the second separator sheet may satisfy the relationship "ΔW2=ΔW1."

[0031] The ratio (ΔW1 / ΔW2) of the first protrusion length ΔW1 to the second protrusion length ΔW2 may be, for example, 1.5 to 5. The ratio (ΔW1 / ΔW2) may be, for example, 2 to 3.

[0032] The difference (ΔW1−ΔW2) between the first protrusion length ΔW1 and the second protrusion length ΔW2 may be, for example, 1 to 5 mm, or may be, for example, 2 to 3 mm.

[0033] The first protrusion length ΔW1 may be, for example, 2 to 5 mm. The first protrusion length ΔW1 may be, for example, 2 to 4 mm. The second protrusion length ΔW2 may be, for example, 0.5 to 1.5 mm. The second protrusion length ΔW2 may be, for example, 0.5 to 1 mm.

[0034] The positive electrode sheet 10 is disposed so as not to protrude from the negative electrode sheet 20 in the width direction. The distance between the leading edge of the positive electrode sheet 10 and the leading edge of the negative electrode sheet 20 in the width direction may be, for example, 0.5 to 2 mm. The positive electrode sheet 10 may include, for example, a metal foil and a positive electrode composite layer. The metal foil may include, for example, Al or the like. The metal foil may have a thickness of, for example, 5 to 50 μm. The positive electrode composite layer may be disposed on only one side of the metal foil. The positive electrode composite layer may be disposed on both sides of the metal foil. The positive electrode composite layer includes a positive electrode active material. The positive electrode active material may include, for example, a Li metal composite oxide or the like. The positive electrode composite layer may have a thickness of, for example, 10 to 1000 μm. For example, the positive electrode composite layer may be formed by coating the surface of the metal foil with a positive electrode slurry. An uncoated portion may be formed on the upper long side of the metal foil. No positive electrode composite layer is formed in the uncoated portion. The metal foil is exposed in the uncoated portion. For example, multiple positive electrode tabs 110P may be joined to the uncoated portion. The multiple positive electrode tabs 110P may be arranged at intervals from one another.

[0035] The negative electrode sheet 20 may include, for example, a metal foil and a negative electrode composite layer. The metal foil may include, for example, Cu. The metal foil may have a thickness of, for example, 5 to 50 μm. The negative electrode composite layer may be disposed on only one side of the metal foil. The negative electrode composite layer may be disposed on both sides of the metal foil. The negative electrode composite layer includes a negative electrode active material. The negative electrode active material may include, for example, graphite, Si, SiO, etc. For example, volume changes (expansion and contraction) of the negative electrode composite layer due to charge and discharge can promote overflow of the electrolyte from the wound electrode body 100. The negative electrode composite layer may have a thickness of, for example, 10 to 1000 μm. For example, the negative electrode composite layer may be formed by coating the surface of the metal foil with negative electrode slurry. An uncoated portion may be formed on the upper long side of the metal foil. The negative electrode composite layer is not formed on the uncoated portion. The metal foil is exposed in the uncoated portion. For example, a plurality of negative electrode tabs 110N may be joined to the uncoated portion. The plurality of negative electrode tabs 110N may be arranged at intervals from one another.

[0036] The separator sheet 30 may have a thickness of, for example, 5 to 50 μm. The separator sheet 30 has insulating properties. The separator sheet 30 may contain, for example, polyethylene (PE), polypropylene (PP), etc. The separator sheet 30 may have a single-layer structure. The separator sheet 30 may be made of, for example, a PE layer. The separator sheet 30 may have a multi-layer structure. The separator sheet 30 may include, for example, a PP layer, a PE layer, and a PP layer in this order. The surface of the separator sheet 30 may be coated with inorganic particles.

[0037] The separator sheet 30 is porous. The separator sheet 30 may have an average pore diameter of, for example, 0.01 to 1 μm. The "average pore diameter" can be measured by mercury intrusion porosimetry. The separator sheet 30 may have an average pore diameter of, for example, 50 to 250 μm / 100 cm. 3 The "Gurley value" can be measured by the Gurley test method.

[0038] <Electrolyte> The electrolyte solution is a liquid electrolyte. The electrolyte solution may contain, for example, a Li salt and an organic solvent. The electrolyte solution is impregnated into the wound electrode body 100. The entire electrolyte solution may be impregnated into the wound electrode body 100. A portion of the electrolyte solution may be present outside the wound electrode body 100. The electrolyte solution present outside the wound electrode body 100 may also be referred to as "excess liquid." Electrolyte solution that overflows from the wound electrode body 100 may be excess liquid. For example, excess liquid may be stored between the wound electrode body 100 and the insulating film 120. For example, excess liquid may be stored in the bottom wall 212 of the case body 210. At the second end E2, the leading end of the separator sheet 30 may be immersed in excess liquid.

[0039] <Other configurations> The connecting member 400 is conductive (see FIG. 3). The connecting member 400 includes a current collector 410. The current collector 410 is connected to a plurality of tabs. The current collector 410 includes a positive current collector 410P and a negative current collector 410N. The positive current collector 410P connects a plurality of positive tabs 110P to positive connecting pins 420P. For example, at least one of the positive current collector 410P and the negative current collector 410N may include a fuse portion. The fuse portion can interrupt a circuit when an overcurrent flows. For example, the fuse portion may melt due to Joule heat.

[0040] The positive terminal 300P includes a positive terminal plate 310, a positive terminal block 320, and a positive connecting pin 420P (see FIG. 3). The positive terminal plate 310 may have, for example, a rectangular parallelepiped outer shape. The positive terminal plate 310 may be made of, for example, a metal. The positive terminal plate 310 may contain, for example, Al or the like. The positive terminal block 320 may be made of, for example, a metal. The positive terminal block 320 may be made of, for example, a different material from that of the positive terminal plate 310. The positive terminal block 320 may have a lower melting point than the positive terminal plate 310. The positive terminal block 320 may contain, for example, Fe or the like. The positive terminal block 320 is joined to the upper surface of the top wall 222. The positive terminal plate 310 is joined to the upper surface of the positive terminal block 320.

[0041] The positive electrode connecting pin 420P may have, for example, a cylindrical outer shape. A through hole is formed in each of the positive electrode terminal plate 310 and the positive electrode terminal block 320. The positive electrode connecting pin 420P is inserted through the through hole. The positive electrode connecting pin 420P is further inserted into the connecting hole 412h. The upper end of the positive electrode connecting pin 420P may be fixed to the positive electrode terminal plate 310 by, for example, crimping.

[0042] The negative electrode terminal 300N includes a negative electrode terminal plate 330 and a negative electrode connecting pin 420N (see FIG. 3). The negative electrode terminal plate 330 may be made of, for example, metal. The negative electrode terminal plate 330 may contain, for example, Cu, Ni, or the like. The insulating member 340 electrically insulates the negative electrode terminal 300N from the top wall 222. The insulating member 340 may be made of, for example, a resin material. The reversal plate 224 may have an outer shape such as a dish shape or a bowl shape. When the internal pressure of the cell case 200 increases, the reversal plate 224 may be reversed. When the reversal plate 224 is reversed, electrical conduction between the top wall 222 and the negative electrode terminal 300N may be established.

[0043] The negative electrode current collector plate 410N connects the plurality of negative electrode tabs 110N and the negative electrode connecting pin 420N. That is, the connecting member 400 electrically connects the wound electrode body 100 and the negative electrode terminal 300N. The negative electrode connecting pin 420N connects the negative electrode current collector plate 410N and the negative electrode terminal plate 330. The negative electrode connecting pin 420N may have, for example, a cylindrical outer shape. The negative electrode connecting pin 420N is inserted into the connecting hole 412h. The upper end of the negative electrode connecting pin 420N may be fixed to the negative electrode terminal plate 330 by, for example, crimping.

[0044] The insulator 500 provides insulation between the connecting member 400 and the cell casing 200. The insulator 500 includes an insulating sheet 510 and an insulating gasket 520. The insulating sheet 510 is connected to the lower surface of the top wall 222. Through holes are formed in the insulating sheet 510 in the height direction at a portion overlapping the pressure release valve 222a, a portion overlapping the liquid injection hole 222b, a portion overlapping each through-hole 222d, and a portion overlapping the reversal plate 224.

[0045] The insulating gasket 520 has a shape that surrounds the connecting pin 420. The insulating gasket 520 provides insulation between the connecting pin 420 and the cell case 200. The insulating gasket 520 includes a positive electrode gasket 520P and a negative electrode gasket 520N. The positive electrode gasket 520P covers the positive electrode connecting pin 420P. The positive electrode gasket 520P has a cylindrical outer shape. The negative electrode gasket 520N covers the negative electrode connecting pin 420N. The negative electrode gasket 520N may have the same structure as the positive electrode gasket 520P. The negative electrode gasket 520N electrically insulates the top wall 222 from the negative electrode terminal 300N. [Explanation of symbols]

[0046] 1 storage cell, 10 positive electrode sheet, 20 negative electrode sheet, 30 separator sheet, 100 wound electrode body, 110N negative electrode tab, 110P positive electrode tab, 120 insulating film, 200 cell case, 210 case body, 211 opening surface, 212 bottom wall, 214 peripheral wall, 220 lid, 222 top wall, 222a pressure release valve, 222b liquid injection hole, 222c sealing member, 222d through hole, 224 reversal plate, 300N negative electrode terminal, 300P positive electrode terminal, 310 positive electrode terminal plate, 320 positive electrode terminal block, 330 negative electrode terminal plate, 340 insulating member, 400 connecting member, 410 current collector, 410N negative electrode current collector, 410P positive electrode current collector, 412h Connecting hole, 420 connecting pin, 420N negative electrode connecting pin, 420P positive electrode connecting pin, 500 insulator, 510 insulating sheet, 520 insulating gasket, 520N negative electrode gasket, 520P positive electrode gasket, E1 first end, E2 second end, ΔW1 first protrusion length, ΔW2 second protrusion length.

Claims

1. The battery includes a wound electrode body, an electrolyte, and a cell case that accommodates the wound electrode body and the electrolyte, the cell casing includes a top wall, a peripheral wall, and a bottom wall; the top wall faces the bottom wall in a first direction, the peripheral wall connects the top wall and the bottom wall, the wound electrode body includes a positive electrode sheet, a separator sheet, and a negative electrode sheet, a winding axis direction of the wound electrode body is along the first direction, the wound electrode body has a first end portion disposed on the top wall side in the winding axis direction and a second end portion disposed on the bottom wall side in the winding axis direction, the positive electrode sheet has a positive electrode tab at the first end, the negative electrode sheet has a negative electrode tab at the first end, the separator sheet protrudes from the negative electrode sheet by a first protrusion length at the first end, the separator sheet protrudes from the negative electrode sheet by a second protrusion length at the second end; and The first protrusion length is longer than the second protrusion length. Energy storage cell.

2. a ratio of the first protrusion length to the second protrusion length is 1.5 to 5; The energy storage cell according to claim 1 .

3. The difference between the first protrusion length and the second protrusion length is 1 to 5 mm. The energy storage cell according to claim 1 .

4. the first protrusion length is 2 to 5 mm; and The second protrusion length is 0.5 to 1.5 mm. The energy storage cell according to claim 1 .

5. the cell case includes a case body and a lid; the case body includes the peripheral wall and the bottom wall, The peripheral wall stands upright from the bottom wall, the case body has an opening surface, the opening surface faces the bottom wall, the lid includes the top wall; and The lid closes the opening. The energy storage cell according to any one of claims 1 to 4.

6. the separator sheet is porous at the second end; The energy storage cell according to claim 1 .

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