Power storage cell

Abstract

To reduce unevenness in a retention amount of an electrolytic solution.SOLUTION: A power storage cell includes a case, an electrolytic solution, and an electrode assembly. The case houses the electrolytic solution and the electrode assembly. The electrode assembly includes a first electrode, a second electrode, a separator, and an interposition film. The first electrode and the second electrode are alternately stacked. The separator separates the first electrode from the second electrode. The interposition film is interposed between the first electrode and the separator. In a plane orthogonal to a stacking direction of the first electrode and the second electrode, the interposition film includes a first region and a second region. The first region includes the center of the interposition film in the plane. The second region surrounds a periphery of the first region. The interposition film satisfies a relationship of a formula (1): [T2<T1]. T1 represents a thickness of the interposition film in the first region. T2 represents a thickness of the interposition film in the second region.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Japanese Patent Application Laid-Open No. 2019-079661 discloses a laminated electrode body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-079661 A Summary of the Invention [Problem to be solved by the invention]

[0004] The power storage cell may include a case, an electrolyte, and an electrode assembly. The case houses the electrolyte and the electrode assembly. The electrode assembly may be broadly classified into a "stacked type" and a "wound type". The wound type may be formed by winding a band-shaped electrode group in a spiral shape. The stacked type may be formed by stacking electrode groups in one direction.

[0005] The electrode assembly includes a separator. The separator is disposed between the electrodes. The separator is porous. The electrolyte permeates the separator, so that the electrolyte can be retained in the gap between the electrodes.

[0006] The electrolyte may leak from the electrode body. In the laminated type, the gap between the electrodes is open around the entire circumference in the direction perpendicular to the lamination direction. For example, when the lamination direction is perpendicular to the vertical direction, the electrolyte may move vertically downward due to the action of gravity. In the vertical downward direction, the electrolyte may leak from the open gap. It is considered that the leakage of the electrolyte causes unevenness in the amount of electrolyte held in the plane perpendicular to the lamination direction.

[0007] An object of the present disclosure is to reduce unevenness in the amount of electrolyte retained. [Means for solving the problem]

[0008] 1. An energy storage cell according to one aspect of the present disclosure includes the following configuration. The energy storage cell includes a case, an electrolyte, and an electrode assembly. The case houses the electrolyte and the electrode assembly. The electrode assembly includes a first electrode, a second electrode, a separator, and an intervening membrane. The first electrode and the second electrode are alternately stacked. The separator separates the first electrode from the second electrode. The intervening membrane is interposed between the first electrode and the separator. In a plane perpendicular to the stacking direction of the first electrode and the second electrode, the intervening membrane includes a first region and a second region. The first region includes a center of the intervening membrane in the same plane. The second region surrounds the periphery of the first region. The intervening membrane satisfies the relationship of the following formula (1). T2 <T1 (1) T1 denotes the thickness of the intervening membrane in the first region, and T2 denotes the thickness of the intervening membrane in the second region.

[0009] In one aspect of the present disclosure, the electrode assembly includes an intervening membrane in addition to the electrodes and the separator. The intervening membrane has a specific thickness distribution. That is, a first region (center) of the intervening membrane is thicker than the surroundings. The movement of the electrolyte around the first region can be inhibited by the first region. It is expected that the unevenness of the amount of electrolyte retained will be reduced by inhibiting the movement of the electrolyte.

[0010] 2. The storage cell described in "1" above may include, for example, the following configuration. The storage cell has a height direction, a width direction, and a thickness direction. The height direction, width direction, and thickness direction are mutually perpendicular. The thickness direction is parallel to the stacking direction. In a plane perpendicular to the stacking direction, the first region extends in the width direction. The second region includes a third region and a fourth region. In the height direction, the first region is disposed between the third region and the fourth region. The intervening film further satisfies the relationship of the following formula (2). T3 <T4 (2) T3 indicates the thickness of the intervening membrane in the third region, and T4 indicates the thickness of the intervening membrane in the fourth region.

[0011] The first region extends in the width direction, which can inhibit the movement of the electrolyte over a wide range. Furthermore, the third region (thin wall portion) is located on one side of the first region (thick wall portion) in the height direction, which is expected to allow the electrolyte to accumulate in the third region. The synergistic effect of these actions is expected to reduce unevenness in the amount of electrolyte retained.

[0012] 3. The storage cell according to the above item "2" may have the following configuration, for example: The intervening film further satisfies the relationships of the following formulas (3) and (4). 10μm≦T1≦20μm (3) T3≦3μm (4)

[0013] 4. The storage cell according to any one of the above items "1" to "3" may include, for example, the following configuration. The intermediate film is formed on at least one surface of the first electrode and the separator. The intermediate film is porous. The intermediate film includes inorganic particles and a binder.

[0014] 5. The energy storage cell according to any one of the above items "2" to "4" may include, for example, the following configuration. The separator includes a zigzag fold portion. In the zigzag fold portion, the separator is folded in a zigzag shape. The separator is folded back at both ends in the height direction. The separator is folded back so as to sandwich the first electrode or the second electrode alternately.

[0015] 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 includes all modifications within the meaning and scope equivalent to the description of the claims. For example, it is also intended from the beginning that any configuration may be extracted from the present embodiment and arbitrarily combined.

[0016] Geometric terms should not be interpreted in a strict sense. Examples of geometric terms include "parallel," "perpendicular," and the like. 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 figure may not match the actual dimensional relationships. The dimensional relationships in each figure may be changed to help the reader understand. For example, the length, width, thickness, and the like may be changed. Furthermore, some configurations may be omitted.

[0017] Numerical ranges such as "m to n%" include both ends unless otherwise specified. That is, "m to n%" indicates a numerical range of "m% or more and n% or less". "m% or more and n% or less" includes "more than m% and less than n%". "More than" and "less than" are represented by an inequality sign with an equal sign "≦". "More than" and "less than" are represented by an inequality sign without an equal sign "<". A numerical value arbitrarily selected from within the numerical range may be set as a new upper limit or lower limit. For example, a new numerical range may be set by arbitrarily combining a numerical value within the numerical range with a numerical value described in another part of this specification, in a table, in a figure, etc. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a schematic perspective view showing an example of a storage cell according to the present embodiment. [Diagram 2] 1 is a schematic cross-sectional view illustrating an example of a storage cell according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a cross-sectional view showing an example of an electrode body in the present embodiment. [Figure 4] FIG. 2 is a schematic plan view showing an example of an intervening film. [Diagram 5] 5 is a cross-sectional view taken along line AA in FIG. 4. [Figure 6] 5 is a cross-sectional view of FIG. 4 taken along line B-B. [Figure 7] 5 is a cross-sectional view taken along CC in FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] 1. Energy storage cell FIG. 1 is a schematic perspective view showing an example of a storage cell in this embodiment. FIG. 2 is a schematic cross-sectional view showing an example of a storage cell in this embodiment. The storage cell 1 may have, for example, a height direction, a width direction, and a thickness direction. The height direction, width direction, and thickness direction are perpendicular to each other. The "height direction" is the H direction in FIG. 1, etc. The "width direction" is the W direction in FIG. 1, etc. The "thickness direction" is the D direction in FIG. 1, etc. The height direction may be parallel to the vertical direction, for example. The width direction and the thickness direction may be parallel to the horizontal direction, for example. "Height" indicates the dimension in the height direction. "Width" indicates the dimension in the width direction. "Thickness" indicates the dimension in the thickness direction, or the thickness of the object.

[0020] The power storage cell 1 includes a case 200, an electrolyte (not shown), and an electrode assembly 100. The electrolyte is a liquid electrolyte. The electrolyte may include, for example, an organic solvent and a lithium salt.

[0021] 2. Electrode body The electrode body 100 may have, for example, a rectangular parallelepiped shape. The "first aspect ratio" refers to the ratio of the width to the height in the electrode body 100. The first aspect ratio may be, for example, 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, 5 or more, or 10 or more. The first aspect ratio may be, for example, 10 or less, 5 or less, 3 or less, 2.5 or less, 2 or less, or 1.5 or less. The "second aspect ratio" refers to the ratio of the thickness to the height in the electrode body 100. The second aspect ratio may be, for example, 0.1 or more, 0.2 or more, 0.3 or more, 0.5 or more, or 1 or more. The second aspect ratio may be, for example, 1 or less, 0.5 or less, 0.3 or less, or 0.2 or less.

[0022] 2-1. 1st electrode, 2nd electrode FIG. 3 is a cross-sectional view showing an example of an electrode assembly in this embodiment. The electrode assembly 100 includes one or more first electrodes 110, one or more second electrodes 120, one or more separators 130, and an intervening film 140. The first electrodes 110 and the second electrodes 120 are alternately stacked in the thickness direction. That is, the thickness direction is parallel to the stacking direction of the first electrodes 110 and the second electrodes 120. The number of the first electrodes 110 and the second electrodes 120 may be any of 2 or more, 5 or more, 10 or more, 50 or more, or 100 or more. The number of the first electrodes 110 and the second electrodes 120 may be any of 200 or less, 100 or less, 50 or less, 10 or less, or 5 or less.

[0023] The second electrode 120 has a different polarity than the first electrode 110. For example, the first electrode 110 may be a positive electrode and the second electrode 120 may be a negative electrode. For example, the first electrode 110 may be a negative electrode and the second electrode 120 may be a positive electrode.

[0024] The first electrode 110 may include, for example, a first current collector 112 and a first active material layer 114. The first current collector 112 may include, for example, a metal foil or the like. The metal foil may include, for example, Al, Cu, Ni, Ti, Fe, or the like. The first active material layer 114 is disposed on a surface of the first current collector 112. The first active material layer 114 may be disposed on only one side of the first current collector 112. The first active material layer 114 may be disposed on both sides of the first current collector 112. The first active material layer 114 includes a positive electrode active material or a negative electrode active material. The positive electrode active material may include, for example, a lithium nickel composite oxide, or the like. The negative electrode active material may include, for example, graphite, SiO, Si, or the like.

[0025] The second electrode 120 may include, for example, a second current collector 122 and a second active material layer 124. The second current collector 122 may include, for example, a metal foil or the like. The second active material layer 124 is disposed on a surface of the second current collector 122. The second active material layer 124 may be disposed on only one side of the second current collector 122. The second active material layer 124 may be disposed on both sides of the second current collector 122. The second active material layer 124 includes a positive electrode active material or a negative electrode active material. The second active material layer 124 may have the same area as the first active material layer 114, or may have a different area. For example, the area of ​​the second active material layer 124 may be larger than the area of ​​the first active material layer 114. The ratio of the area of ​​the second active material layer 124 to the area of ​​the first active material layer 114 may be, for example, any of 1.01 or more, 1.05 or more, or 1.1 or more. The ratio of the area of ​​the second active material layer 124 to the area of ​​the first active material layer 114 may be, for example, any of 1.1 or less, 1.05 or less, or 1.01 or less.

[0026] 2-2.Separator The separator 130 has electrical insulation properties. The separator 130 is porous. The separator 130 may include, for example, a microporous film made of polyolefin. The thickness of the separator 130 may be, for example, 5 to 50 μm, 5 to 30 μm, or 5 to 15 μm. The separator 130 separates the first electrode 110 from the second electrode 120. The separator 130 may be, for example, two or more sheets. For example, the separator 130 may be inserted between each of the first electrode 110 and the second electrode 120.

[0027] The separator 130 may be, for example, a single sheet. For example, the separator 130 may include a zigzag fold portion 135. In the zigzag fold portion 135, the separator 130 is folded in a zigzag shape. The zigzag fold portion 135 includes a planar portion 131 and a folded portion 132. In the planar portion 131, the separator 130 extends in a planar shape. In the folded portion 132, the separator 130 is folded. The folded portion 132 is disposed at both ends in the height direction. The separator 130 is folded so as to alternately sandwich the first electrode 110 or the second electrode 120. The planar portion 131 sandwiches the first electrode 110 or the second electrode 120. The separator 130 may further include, for example, an outer peripheral portion 136. The outer peripheral portion 136 may be wound so as to wrap the zigzag fold portion 135. Note that, zigzag folds may be formed by folding back separator 130 at both ends in the width direction.

[0028] 3.Intervening membrane The intermediate film 140 is interposed at least between the first electrode 110 and the separator 130. The intermediate film 140 may also be interposed between the second electrode 120 and the separator 130. The intermediate film 140 may be porous. The porosity of the intermediate film 140 may be higher or lower than the porosity of the separator 130. The average pore size of the intermediate film 140 may be higher or lower than the average pore size of the separator 130.

[0029] The intervening film 140 may include, for example, a heat-resistant material. The intervening film 140 may include, for example, inorganic particles and a binder. The intervening film 140 may include, for example, 0.1 to 50% by mass of the binder, with the remainder being inorganic particles. The mass fraction of the binder may be, for example, 1 to 30%, 1 to 10%, 1 to 5%, or 1 to 3%.

[0030] The inorganic particles may include at least one selected from the group consisting of alumina, boehmite, titania, magnesia, silica, and zirconia. The binder may include at least one selected from the group consisting of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, styrene butadiene rubber, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl butyral, polyethylene oxide, polyacrylic acid, acrylic resin, and methacrylic resin.

[0031] The intermediate film 140 may be, for example, a self-supporting film. The term "self-supporting film" refers to a film that maintains its shape by itself. The intermediate film 140 may be, for example, a non-self-supporting film. The term "non-self-supporting film" refers to a film that maintains its shape by being supported by a support. For example, the intermediate film 140 may be supported by at least one of the first electrode 110 and the separator 130. That is, the intermediate film 140 may be formed on the surface of at least one of the first electrode 110 and the separator 130. For example, the intermediate film 140 may be formed by applying a heat-resistant material to the surface of the separator 130. For example, the intermediate film 140 may be formed by applying a heat-resistant material to the surface of the first electrode 110. For example, the intermediate film 140 may be formed by applying a heat-resistant material to the surfaces of both the first electrode 110 and the separator 130. When separator 130 includes zigzag portion 135 , intervening film 140 may be formed only on flat portion 131 , or may be formed on both flat portion 131 and folded portion 132 .

[0032] FIG. 4 is a schematic plan view showing an example of an intervening film. FIG. 4 shows a plane perpendicular to the stacking direction (thickness direction). This plane is parallel to the height direction and width direction. Intervening film 140 includes first region 141 and second region 142. First region 141 includes center 145 of intervening film 140. The "center" refers to the geometric center of the figure formed by the contour line of intervening film 140. First region 141 is, so to speak, a thick portion. First region 141 can hinder the movement of the electrolyte. It is expected that the first region 141 hinders the movement of the electrolyte, thereby reducing unevenness in the amount of electrolyte retained.

[0033] The first region 141 may extend in the width direction, for example. The ratio of the width of the intervening film 140 to the width of the electrode body 100 may be, for example, 0.25 or more, 0.5 or more, or 0.75 or more. The ratio of the width of the intervening film 140 to the width of the electrode body 100 may be, for example, 0.75 or less, 0.5 or less, or 0.25 or less. The ratio of the height of the intervening film 140 to the height of the electrode body 100 may be, for example, 0.01 or more, 0.05 or more, 0.1 or more, 0.2 or more, or 0.3 or more. The ratio of the height of the intervening film 140 to the height of the electrode body 100 may be, for example, 0.3 or less, 0.2 or less, 0.1 or less, 0.05 or less, or 0.01 or less.

[0034] The second region 142 surrounds the periphery of the first region 141. The second region 142 may include, for example, a third region 143 and a fourth region 144. In the height direction, the first region 141 is disposed between the third region 143 and the fourth region 144. The third region 143 is, so to speak, a thin-walled portion. An electrolyte can be stored in the third region 143.

[0035] For example, the third region 143 may be located vertically above the first region 141. When the height direction is parallel to the vertical direction, the region vertically above the first region 141 tends to have the lowest amount of electrolyte retention. For example, the larger the first aspect ratio of the electrode body 100, the more pronounced this tendency may be. By having this region be a thin-walled portion (a portion for storing electrolyte), it is expected that unevenness in the amount of electrolyte retention will be reduced.

[0036] The fourth region 144 may be adjacent to the third region 143. The fourth region 144 may be adjacent to the first region 141. The fourth region 144 may be disposed on both sides of the third region 143 in the width direction. The fourth region 144 may be disposed on both sides of the first region 141 in the width direction. The fourth region 144 may be located vertically below the first region 141.

[0037] Fig. 5 is a cross-sectional view taken along line AA in Fig. 4. Fig. 6 is a cross-sectional view taken along line BB in Fig. 4. Fig. 7 is a cross-sectional view taken along line CC in Fig. 4. The intervening film 140 satisfies the relationship of the following formula (1). T2 <T1 (1) T1 denotes the thickness of the intervening film 140 in the first region 141. T2 denotes the thickness of the intervening film 140 in the second region 142.

[0038] The ratio of T1 to T2 (T1 / T2) may be, for example, any of 1.01 or more, 1.05 or more, 1.1 or more, 1.2 or more, 1.5 or more, or 2 or more. The ratio (T1 / T2) may be, for example, any of 3 or less, 2 or less, 1.5 or less, 1.2 or less, 1.1 or less, or 1.05 or less.

[0039] The intervening film 140 may satisfy, for example, the relationship of the following formula (2). T3 <T4 (2) T3 indicates the thickness of the intervening film 140 in the third region 143. T4 indicates the thickness of the intervening film 140 in the fourth region 144.

[0040] The ratio of T3 to T4 (T3 / T4) may be, for example, 0.99 or less, 0.95 or less, 0.90 or less, 0.75 or less, or 0.5 or less. The ratio (T3 / T4) may be, for example, 0.3 or more, 0.5 or more, 0.75 or more, 0.90 or more, or 0.95 or more.

[0041] When the above formula (2) is satisfied, the following formula (2)' is also satisfied. T3 <T4≦T2 (2)’

[0042] The intervening film 140 may satisfy the relationships of the following formulas (3) and (4), for example. 10μm≦T1≦20μm (3) T3≦3μm (4)

[0043] T1 may be, for example, any one of 11 μm or more, 12.5 μm or more, 15 μm or more, 17.5 μm or more, or 19 μm or more. T1 may be any one of 17.5 μm or less, 15 μm or less, 12.5 μm or less, or 11 μm or less.

[0044] T3 may be, for example, 2.5 μm or less, 2 μm or less, 1.5 μm or less, 1 μm or less, 0.5 μm or less, or 0.1 μm or less. T3 may be, for example, 0.1 μm or more, 0.5 μm or more, 1 μm or more, 1.5 μm or more, 2 μm or more, or 2.5 μm or more.

[0045] T4(T2) may be, for example, any of more than 3 μm, 3.5 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more. T4(T2) may be, for example, any of less than 10 μm, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, 4 μm or less, or 3.5 μm or less.

[0046] 4. Case The case 200 houses the electrolyte and the electrode assembly 100. The case 200 may be sealed. The case 200 may be sealed. The case 200 may include, for example, a can 210 and a lid 220. The can 210 has an opening. The opening opens in the height direction. The opening may open, for example, vertically upward. The can 210 may be made of metal, for example. The can 210 may include, for example, Al or the like. The can 210 may include, for example, a bottom wall 212 and a peripheral wall 214. The bottom wall 212 may be, for example, flat. The planar shape of the bottom wall 212 may be, for example, rectangular. The peripheral wall 214 stands up from the bottom wall 212. The peripheral wall 214 may be, for example, a rectangular tube. The width of the peripheral wall 214 may be greater than the thickness of the peripheral wall 214. The height of the peripheral wall 214 may be greater than the thickness of the peripheral wall 214. Note that the "thickness of the peripheral wall 214" here refers to the outer dimension of the case 200 in the thickness direction.

[0047] The lid 220 closes the opening of the can 210. The lid 220 may be welded to the peripheral wall 214. The lid 220 may be, for example, flat. The lid 220 may be made of metal. The lid 220 may include, for example, Al, etc. The lid 220 may include, for example, a pressure release valve 222, a sealing member 224, etc.

[0048] The pressure relief valve 222 may be disposed, for example, near the center of the lid 220. The pressure relief valve 222 releases the internal pressure of the case 200. When the internal pressure reaches or exceeds a set value, the pressure relief valve 222 can be opened. The sealing member 224 seals the liquid filling hole 221. An electrolyte can be poured through the liquid filling hole 221.

[0049] A pair of external terminals 300 are fixed to the lid 220. The external terminals 300 are connected to the first electrode 110 or the second electrode 120. The external terminals 300 may be made of metal, for example. The external terminals may contain Al, Cu, Ni, or the like. The external terminals may have, for example, a rectangular parallelepiped shape. The external terminals 300 may be connected to a bus bar (not shown).

[0050] A pair of connecting members 400 connect the electrode tabs to the external terminals 300. The electrode tabs refer to the first electrode tab 116 or the second electrode tab 126. The two connecting members 400 may have substantially the same structure.

[0051] The connecting member 400 may include, for example, a current collecting tab 410, a sub-tab 420, and a connecting pin 430. The current collecting tab 410 includes a side portion 412 and an upper portion 414. The side portion 412 is located on a side of the electrode body 100 in the width direction. The upper portion 414 is located above the electrode body 100. The upper portion 414 extends from an upper end of the side portion 412 toward the inside in the width direction.

[0052] The sub-tab 420 connects the electrode tabs to the current collecting tab 410. The sub-tab 420 may include a first end 422 and a second end 424. The first end 422 is connected to the electrode tabs. The second end 424 is connected to the side portion 412.

[0053] The connecting pin 430 connects the current collecting tab 410 to the external terminal 300. The connecting pin 430 connects the upper portion 414 to the external terminal 300. For example, a lower end of the connecting pin 430 may be inserted into a through hole provided in the upper portion 414.

[0054] 5. Insulating materials The insulating member 500 insulates the case 200 from the connecting member 400. The insulating member 500 may include a first portion 510, a second portion 520, a third portion 530, and a fourth portion 540, for example.

[0055] The first part 510 is fixed to the upper surface of the lid 220. The first part 510 is disposed between the lid 220 and the external terminal 300. The second part 520 is fixed to the lower surface of the lid 220. The second part 520 is disposed between the lid 220 and the upper part 414. The second part 520 is disposed between the lid 220 and a lower part of the connecting pin 430. The third part 530 is disposed between the connecting pin 430 and the lid 220. The third part 530 is cylindrical. The third part 530 surrounds the connecting pin 430. The first part 510, the second part 520 and the third part 530 are provided with through holes. The connecting pin 430 is inserted through the through holes.

[0056] The fourth part 540 is plate-shaped. It is fixed to the lower surface of the upper part 414. The fourth part 540 is disposed above the electrode body 100. In the fourth part 540, a through hole is provided below the pressure release valve 222. In the fourth part 540, a through hole is also provided below the liquid injection port 221. [Explanation of symbols]

[0057] 1 Energy storage cell, 100 Electrode body, 110 First electrode, 112 First current collector, 114 First active material layer, 116 First electrode tab, 120 Second electrode, 122 Second current collector, 124 Second active material layer, 126 Second electrode tab, 130 Separator, 131 Planar portion, 132 Folded portion, 135 Zigzag portion, 136 Outer periphery, 140 Intervening membrane, 141 First region, 142 Second region, 143 Third region, 144 Fourth region, 145 Center, 200 Case, 210 Can, 212 Bottom wall, 214 Peripheral wall, 220 Lid, 221 Inlet, 222 Pressure release valve, 224 Sealing member, 300 External terminal, 400 Connecting member, 410 Current collecting tab, 412 Side portion, 414, upper portion, 420, subtab, 422, first end, 424, second end, 430, connecting pin, 500, insulating member, 510, first portion, 520, second portion, 530, third portion, 540, fourth portion.

Claims

1. The battery includes a case, an electrolyte, and an electrode assembly. The case accommodates the electrolyte and the electrode body, The electrode assembly includes a first electrode, a second electrode, a separator, and an intervening membrane, the first electrodes and the second electrodes are alternately stacked, the separator separates the first electrode from the second electrode; the intermediate film is interposed between the first electrode and the separator, In a plane perpendicular to the stacking direction of the first electrode and the second electrode, the intervening membrane includes a first region and a second region; the first region includes a center of the intervening membrane in the plane; The second region surrounds the first region, The intervening membrane has the formula (1): T2<T1 (1) Fulfilling the relationship, In the formula (1), T1 denotes a thickness of the intervening film in the first region; and T2 represents the thickness of the intervening film in the second region; Energy storage cell.

2. having a height direction, a width direction and a thickness direction, the height direction, the width direction, and the thickness direction are perpendicular to each other, The thickness direction is parallel to the stacking direction, In the plane perpendicular to the stacking direction, The first region extends in the width direction, the second region includes a third region and a fourth region, In the height direction, the first region is disposed between the third region and the fourth region, The intervening membrane has the formula (2): T3 < T4 (2) Further satisfying the relationship In the formula (2), T3 denotes a thickness of the intervening film in the third region; and T4 indicates the thickness of the intervening film in the fourth region; The storage cell according to claim 1 .

3. The intervening membrane has the formulas (3) and (4): 10 μm≦T1≦20 μm (3) T3≦3 μm (4) Further satisfying the relationship of The storage cell according to claim 2 .

4. the intermediate film is formed on a surface of at least one of the first electrode and the separator, the intermediate membrane is porous; and The intermediate film includes inorganic particles and a binder. The storage cell according to claim 2 .

5. The separator includes a zigzag portion, In the zigzag fold portion, the separator is folded in a zigzag shape, The separator is folded back at both ends in the height direction, and The separator is folded back so as to alternately sandwich the first electrodes or the second electrodes. The storage cell according to any one of claims 2 to 4.

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