Electric storage device

Abstract

The electricity storage element includes a case, an electrolyte, and an electrode body. The case accommodates the electrolyte and the electrode body. The electrode body includes a first electrode, a second electrode, a separator, and an interposer. The first electrodes and the second electrodes are alternately stacked. The separator separates the first electrode from the second electrode. The interposer is interposed between the first electrode and the separator. The interposer includes a first region and a second region in a plane orthogonal to a stacking direction of the first electrode and the second electrode. The first region includes a center of the interposer in a plane. The second region surrounds the first region. The interposer satisfies the relationship of formula (1) "T2 < T1". T1 represents a thickness of the interposer in the first region. T2 represents a thickness of the interposer in the second region.

Description

Technical Field

[0001] The present disclosure relates to an electric storage element. Background Art

[0002] Japanese Patent Application Publication No. 2019-079661 discloses a stacked electrode body. Summary of the invention

[0003] The storage element may include a shell, an electrolyte and an electrode body. The shell contains the electrolyte and the electrode body. The electrode body can be roughly divided into a "stacked type" and a "wound type". The wound type can be formed by winding a strip-shaped electrode group into a spiral shape. The stacked type can be formed by stacking the electrode group in one direction.

[0004] The electrode body includes a separator. The separator is arranged between the electrodes. The separator is porous. By allowing the electrolyte to penetrate into the separator, the electrolyte can be retained in the gap between the electrodes.

[0005] Sometimes the electrolyte leaks from the electrode body. In the stacked type, the gap between the electrodes is open over the entire circumference in the direction perpendicular to the stacking direction. For example, when the stacking direction is perpendicular to the vertical direction, the electrolyte can move downward in the vertical direction due to the effect of gravity. In the vertical direction, the electrolyte may leak from the gap of the opening. It is believed that due to the leakage of the electrolyte, the amount of electrolyte retained in the plane perpendicular to the stacking direction is uneven.

[0006] An object of the present disclosure is to reduce the variation in the amount of electrolyte retained.

[0007] 1. An electric storage element according to one aspect of the present disclosure includes the following structure. The electric storage element includes a shell, an electrolyte and an electrode body. The shell contains the electrolyte and the electrode body. The electrode body includes a first electrode, a second electrode, a separator and an intermediate membrane. The first electrode and the second electrode are alternately stacked. The separator separates the first electrode from the second electrode. The intermediate membrane is between the first electrode and the separator. In a plane orthogonal to the stacking direction of the first electrode and the second electrode, the intermediate membrane includes a first region and a second region. The first region includes the center of the intermediate membrane in the plane. The second region surrounds the periphery of the first region. The intermediate membrane satisfies the relationship of the following formula (1):

[0008] T2<T1 (1),

[0009] T1 represents the thickness of the interposer film in the first region, and T2 represents the thickness of the interposer film in the second region.

[0010] In one aspect of the present disclosure, the electrode body includes an intermediate membrane in addition to the electrode and the separator. The intermediate membrane has a specific thickness distribution. That is, the first region (center) of the intermediate membrane is thicker than the surrounding area. The electrolyte around the first region can be blocked from moving by the first region. By blocking the movement of the electrolyte, it is expected to reduce the unevenness of the amount of electrolyte retained.

[0011] 2. The storage element described in "1" may include the following structure, for example. The storage element has a height direction, a width direction and a thickness direction. The height direction, the width direction and the thickness direction are orthogonal to each other. The thickness direction is parallel to the stacking direction. In a plane orthogonal to the stacking direction, the first region extends in the width direction. The second region includes the third region and the fourth region. In the height direction, the first region is arranged between the third region and the fourth region.

[0012] The intermediate film also satisfies the following relationship (2):

[0013] T3<T4 (2),

[0014] T3 represents the thickness of the intermediate film in the third region. T4 represents the thickness of the intermediate film in the fourth region.

[0015] By extending the first region in the width direction, the movement of the electrolyte can be hindered in a wide range. Furthermore, by having the third region (thin-walled portion) on one side of the first region (thick-walled portion) in the height direction, the electrolyte can be expected to be stored in the third region. Through the synergistic effect of these effects, it can be expected to reduce the unevenness of the amount of electrolyte retained.

[0016] 3. The power storage element described in the above “2” may include the following configuration, for example. The interlayer film further satisfies the relationship between the following equations (3) and (4):

[0017] 10μm≤T1≤20μm (3),

[0018] T3≤3μm (4).

[0019] 4. The electric storage element described in any one of "1" to "3" may include the following configurations. The intermediary membrane is formed on the surface of at least one of the first electrode and the separator. The intermediary membrane is porous. The intermediary membrane includes inorganic particles and a binder.

[0020] 5. The storage element described in any one of "2" to "4" may include the following configurations. The separator includes a zigzag portion. In the zigzag portion, the separator is folded into a zigzag shape. The separator is folded back at both ends in the height direction. The separator is folded back in a manner that alternately sandwiches the first electrode or the second electrode.

[0021] The following describes an embodiment of the present disclosure (hereinafter referred to as "the present embodiment"). However, the present embodiment does not limit the technical scope of the present disclosure. The present embodiment is illustrative in all aspects. The present embodiment is non-restrictive. The technical scope of the present disclosure includes all changes within the meaning and scope equivalent to the description of the claimed scope. For example, it is also envisioned from the beginning to extract arbitrary structures from the present embodiment and combine them arbitrarily.

[0022] Geometric terms should not be understood in a strict sense. As geometric terms, for example, "parallel", "perpendicular", "orthogonal", etc. are exemplified. For example, for "parallel", it is acceptable to deviate slightly from the strict sense of "parallel". Geometric terms may include, for example, tolerances and errors in design, operation, and manufacturing. The dimensional relationships in the figures are sometimes inconsistent with the actual dimensional relationships. In order to help the reader understand, the dimensional relationships in the figures are sometimes changed. For example, there are cases where the length, width, thickness, etc. are changed. In addition, some structures are sometimes omitted.

[0023] Unless otherwise specified, numerical ranges such as "m to n%" are inclusive. That is, "m to n%" means a numerical range of "above m% and below n%. "Above m% and below n%" includes "more than m% and less than n%. "Above" and "below" are represented by an inequality sign "≤" with an equal sign. "Exceeding" and "less than" are represented by an inequality sign "<" that does not contain an equal sign. A numerical value arbitrarily selected from the numerical range can also be set as a new upper limit or lower limit. For example, a new numerical range can also be set by arbitrarily combining numerical values ​​within the numerical range with numerical values ​​recorded in other parts, tables, figures, etc. in this specification.

[0024] The foregoing and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic perspective view showing an example of an electric storage element in this embodiment.

[0026] Figure 2 It is a schematic cross-sectional view showing an example of the electric storage element in this embodiment.

[0027] Figure 3 It is a cross-sectional view showing an example of the electrode body in this embodiment.

[0028] Figure 4 It is a schematic plan view showing an example of an interposer film.

[0029] Figure 5 yes Figure 4 AA section view.

[0030] Figure 6 yes Figure 4 BB cross-sectional view.

[0031] Figure 7 yes Figure 4 CC cross-sectional view. DETAILED DESCRIPTION

[0032] -Electrical storage element-

[0033] Figure 1 It is a schematic perspective view showing an example of an electric storage element in this embodiment. Figure 2 1 is a schematic cross-sectional view showing an example of an electric storage element in this embodiment. The electric storage element 1 may have, for example, a height direction, a width direction, and a thickness direction. The height direction, the width direction, and the thickness direction are orthogonal to each other. The “height direction” is Figure 1 The width direction is Figure 1 The thickness direction is Figure 1 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.

[0034] The electric storage element 1 includes a housing 200 , an electrolyte (not shown), and an electrode body 100 . The electrolyte is a liquid electrolyte and may contain, for example, an organic solvent and a lithium salt.

[0035] -Electrode body-

[0036] The electrode body 100 may also have a rectangular parallelepiped shape, for example. The "first aspect ratio" represents the ratio of the width to the height in the electrode body 100. The first aspect ratio may be, for example, any one of greater than 1, greater than 1.5, greater than 2, greater than 2.5, greater than 3, greater than 5, and greater than 10. The first aspect ratio may be, for example, any one of less than 10, less than 5, less than 3, less than 2.5, less than 2, and less than 1.5. The "second aspect ratio" represents the ratio of the thickness to the height in the electrode body 100. The second aspect ratio may be, for example, any one of greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.5, and greater than 1. The second aspect ratio may be, for example, any one of less than 1, less than 0.5, less than 0.3, and less than 0.2.

[0037] -First electrode, second electrode-

[0038] Figure 31 is a cross-sectional view showing an example of an electrode body in the present embodiment. The electrode body 100 includes one or more first electrodes 110, one or more second electrodes 120, one or more separators 130, and an intermediate film 140. In the thickness direction, the first electrode 110 and the second electrode 120 are alternately stacked. That is, the thickness direction is parallel to the stacking direction of the first electrode 110 and the second electrode 120. The number of the first electrode 110 and the second electrode 120 can be any one of more than 2 sheets, more than 5 sheets, more than 10 sheets, more than 50 sheets, and more than 100 sheets, respectively. The number of the first electrode 110 and the second electrode 120 can be any one of less than 200 sheets, less than 100 sheets, less than 50 sheets, less than 10 sheets, and less than 5 sheets, respectively.

[0039] The second electrode 120 has a different polarity from 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.

[0040] 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 also include, for example, a metal foil, etc. The metal foil may include, for example, Al, Cu, Ni, Ti, Fe, etc. The first active material layer 114 is disposed on the surface of the first current collector 112. The first active material layer 114 may also be disposed only on one side of the first current collector 112. The first active material layer 114 may also 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, etc. The negative electrode active material may include, for example, graphite, SiO, Si, etc.

[0041] 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 also include, for example, a metal foil or the like. The second active material layer 124 is disposed on the surface of the second current collector 122. The second active material layer 124 may also be disposed only on one side of the second current collector 122. The second active material layer 124 may also 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 greater 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 one of 1.01 or more, 1.05 or more, and 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 one of 1.1 or less, 1.05 or less, and 1.01 or less.

[0042] - Partition -

[0043] The separator 130 has electrical insulation. 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, any one of 5 to 50 μm, 5 to 30 μm, and 5 to 15 μm. The separator 130 separates the first electrode 110 from the second electrode 120. For example, the separator 130 may be two or more. For example, the separator 130 may be inserted one by one between each first electrode 110 and the second electrode 120.

[0044] The separator 130 may be, for example, a single sheet. For example, the separator 130 may also include a zigzag portion 135. In the zigzag portion 135, the separator 130 is folded into a zigzag shape. The zigzag 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 back. The folded portion 132 is arranged at both ends in the height direction. The separator 130 is folded back in a manner of alternately sandwiching 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 also include, for example, an outer peripheral portion 136. The outer peripheral portion 136 may also be wound in a manner of surrounding the zigzag portion 135. In addition, the zigzag portion may be formed by folding back the separator 130 at both ends in the width direction.

[0045] -Intermediate film-

[0046] The intermediary membrane 140 is at least interposed between the first electrode 110 and the separator 130. The intermediary membrane 140 may also be interposed between the second electrode 120 and the separator 130. The intermediary membrane 140 may also be porous. The porosity of the intermediary membrane 140 may be higher or lower than the porosity of the separator 130. The average pore diameter of the intermediary membrane 140 may be higher or lower than the average pore diameter of the separator 130.

[0047] The intermediary film 140 may include, for example, a heat-resistant material, etc. The intermediary film 140 may include, for example, inorganic particles and a binder. The intermediary film 140 may include, for example, 0.1 to 50% of a binder by mass fraction and the remainder of inorganic particles. The mass fraction of the binder may be, for example, any one of 1 to 30%, 1 to 10%, 1 to 5%, and 1 to 3%.

[0048] The inorganic particles may include, for example, at least one selected from alumina, boehmite, titanium dioxide, magnesium oxide, silicon dioxide, and zirconium oxide. The binder may include, for example, at least one selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, styrene butadiene rubber, carboxymethyl cellulose, polyvinyl alcohol, polyvinyl butyral, polyethylene oxide, polyacrylic acid, acrylic resin, and methacrylic resin.

[0049] The intermediary film 140 may be, for example, a self-supporting film. A "self-supporting film" refers to a film that maintains its own shape. The intermediary film 140 may be, for example, a non-self-supporting film. A "non-self-supporting film" refers to a film that maintains its shape by being supported by a support. For example, the intermediary film 140 may be supported by at least one of the first electrode 110 and the separator 130. That is, the intermediary film 140 may be formed on the surface of at least one of the first electrode 110 and the separator 130. For example, the intermediary film 140 may be formed by applying a heat-resistant material to the surface of the separator 130. For example, the intermediary film 140 may also be formed by applying a heat-resistant material to the surface of the first electrode 110. For example, the intermediary film 140 may also be formed by applying a heat-resistant material to the surface of both the first electrode 110 and the separator 130. In the case where the separator 130 includes a zigzag portion 135, the intermediary film 140 may be formed only on the plane portion 131, or may be formed on both the plane portion 131 and the folded portion 132.

[0050] Figure 4 FIG. 1 is a schematic top view showing an example of an interposer film. Figure 4 , a plane orthogonal to the stacking direction (thickness direction) is shown. The plane is parallel to the height direction and the width direction. The intermediary film 140 includes a first region 141 and a second region 142. The first region 141 includes a center 145 of the intermediary film 140. The "center" represents the geometric center of the figure formed by the contour line of the intermediary film 140. The first region 141 can be said to be a thick wall portion. The first region 141 can hinder the movement of the electrolyte. By hindering the movement of the electrolyte in the first region 141, it is expected to reduce the unevenness of the amount of electrolyte retained.

[0051] The first region 141 may also extend in the width direction, for example. The ratio of the width of the intermediary film 140 to the width of the electrode body 100 may be, for example, any one of greater than 0.25, greater than 0.5, and greater than 0.75. The ratio of the width of the intermediary film 140 to the width of the electrode body 100 may be, for example, any one of less than 0.75, less than 0.5, and less than 0.25. The ratio of the height of the intermediary film 140 to the height of the electrode body 100 may be, for example, any one of greater than 0.01, greater than 0.05, greater than 0.1, greater than 0.2, and greater than 0.3. The ratio of the height of the intermediary film 140 to the height of the electrode body 100 may be, for example, any one of less than 0.3, less than 0.2, less than 0.1, less than 0.05, and less than 0.01.

[0052] The second region 142 surrounds 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 may be a thin-walled portion. The electrolyte may be stored in the third region 143.

[0053] For example, the third region 143 may also 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 most reduced amount of electrolyte. For example, the larger the first aspect ratio of the electrode body 100, the more significant this tendency may be. By making this region a thin-walled portion (reservation portion of the electrolyte), it is expected to reduce the uneven amount of electrolyte retained.

[0054] The fourth region 144 may be adjacent to the third region 143. The fourth region 144 may be adjacent to the first region 141. In the width direction, the fourth region 144 may be arranged on both sides of the third region 143. In the width direction, the fourth region 144 may be arranged on both sides of the first region 141. The fourth region 144 may be located vertically below the first region 141.

[0055] Figure 5 yes Figure 4 AA section view. Figure 6 yes Figure 4 BB cross-sectional view. Figure 7 yes Figure 4 The interposer film 140 satisfies the relationship of the following formula (1).

[0056] T2<T1 (1)

[0057] T1 represents the thickness of the interposer film 140 in the first region 141 , and T2 represents the thickness of the interposer film 140 in the second region 142 .

[0058] The ratio of T1 to T2 (T1 / T2) may be, for example, any one of 1.01 or more, 1.05 or more, 1.1 or more, 1.2 or more, 1.5 or more, and 2 or more. The ratio (T1 / T2) may be, for example, any one of 3 or less, 2 or less, 1.5 or less, 1.2 or less, 1.1 or less, and 1.05 or less.

[0059] The interposer film 140 may satisfy the relationship of the following formula (2), for example.

[0060] T3<T4 (2)

[0061] T3 represents the thickness of the interposer film 140 in the third region 143. T4 represents the thickness of the interposer film 140 in the fourth region 144.

[0062] The ratio of T3 to T4 (T3 / T4) may be, for example, any one of 0.99 or less, 0.95 or less, 0.90 or less, 0.75 or less, and 0.5 or less. The ratio (T3 / T4) may be, for example, any one of 0.3 or more, 0.5 or more, 0.75 or more, 0.90 or more, and 0.95 or more.

[0063] In addition, when the above formula (2) is satisfied, the following formula (2)' is also satisfied.

[0064] T3<T4≤T2 (2)'

[0065] The interposer film 140 may satisfy the relationship of the following equations (3) and (4), for example.

[0066] 10μm≤T1≤20μm (3)

[0067] T3≤3μm (4)

[0068] 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, and 19 μm or more. T1 may be any one of 17.5 μm or less, 15 μm or less, 12.5 μm or less, and 11 μm or less.

[0069] T3 may be, for example, any one of 2.5 μm or less, 2 μm or less, 1.5 μm or less, 1 μm or less, 0.5 μm or less, and 0.1 μm or less. T3 may be, for example, any one of 0.1 μm or more, 0.5 μm or more, 1 μm or more, 1.5 μm or more, 2 μm or more, and 2.5 μm or more.

[0070] T4(T2) may be, for example, any one 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, and 9 μm or more. T4(T2) may be, for example, any one 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, and 3.5 μm or less.

[0071] -case-

[0072] The shell 200 contains the electrolyte and the electrode body 100. The shell 200 may also be sealed. The shell 200 may also be sealed. The shell 200 may also include, for example, a tank 210 and a cover 220. The tank 210 has an opening. The opening is open in the height direction. The opening may be opened vertically upward, for example. The tank 210 may also be made of metal, for example. The tank 210 may also contain Al, etc. For example, the tank 210 may also include a bottom wall 212 and a peripheral wall 214. The bottom wall 212 may also be in the shape of a flat plate, for example. The planar shape of the bottom wall 212 may also be in the shape of a rectangle, for example. The peripheral wall 214 stands up from the bottom wall 212. The peripheral wall 214 may also be in the shape of a square tube, for example. The width of the peripheral wall 214 may also be greater than the thickness of the peripheral wall 214. The height of the peripheral wall 214 may also be greater than the thickness of the peripheral wall 214. In addition, the "thickness of the peripheral wall 214" here refers to the outer dimensions of the shell 200 in the thickness direction.

[0073] The cover 220 blocks the opening of the tank 210. The cover 220 may be welded to the peripheral wall 214. The cover 220 may be, for example, a flat plate. The cover 220 may be, for example, made of metal. The cover 220 may include, for example, Al. The cover 220 may include, for example, a pressure release valve 222 and a sealing member 224.

[0074] The pressure release valve 222 may be disposed near the center of the cover 220, for example. The pressure release valve 222 releases the internal pressure of the housing 200. When the internal pressure reaches a set value or more, the pressure release valve 222 can be opened. The sealing member 224 seals the liquid injection port 221. The electrolyte can be injected from the liquid injection port 221.

[0075] A pair of external terminals 300 are fixed to the cover 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 also include Al, Cu, Ni, etc. The external terminals may also have a rectangular shape, for example. The external terminals 300 may also be connected to a bus bar (not shown).

[0076] The pair of connecting members 400 connects the electrode sheet to the external terminal 300. The electrode sheet refers to the first electrode sheet 116 or the second electrode sheet 126. The two connecting members 400 may have substantially the same structure.

[0077] The connecting member 400 may also include, for example, a collector tab 410, a sub-piece 420, and a connecting pin 430. The collector tab 410 includes a side portion 412 and an upper portion 414. The side portion 412 is located on the 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 the upper end of the side portion 412 toward the inner side in the width direction.

[0078] The secondary sheet 420 connects the plurality of electrode sheets to the collector tab 410 . The secondary sheet 420 may also include a first end 422 and a second end 424 . The first end 422 is connected to the plurality of electrode sheets, and the second end 424 is connected to the side portion 412 .

[0079] The connecting pin 430 connects the collector tab 410 and the external terminal 300. The connecting pin 430 connects the upper portion 414 and the external terminal 300. For example, the lower end portion of the connecting pin 430 may be inserted into a through hole provided in the upper portion 414.

[0080] -Insulation parts-

[0081] The insulating member 500 insulates the housing 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.

[0082] The first part 510 is fixed to the upper surface of the cover 220. The first part 510 is arranged between the cover 220 and the external terminal 300. The second part 520 is fixed to the lower surface of the cover 220. The second part 520 is arranged between the cover 220 and the upper part 414. The second part 520 is arranged between the cover 220 and the lower part of the connecting pin 430. The third part 530 is arranged between the connecting pin 430 and the cover 220. The third part 530 is cylindrical. The third part 530 surrounds the connecting pin 430. Through holes are provided in the first part 510, the second part 520 and the third part 530. The connecting pin 430 is inserted into the through hole.

[0083] The fourth portion 540 is plate-shaped and fixed to the lower surface of the upper portion 414. The fourth portion 540 is disposed above the electrode body 100. A through hole is provided below the pressure release valve 222 in the fourth portion 540. A through hole is also provided below the liquid injection port 221 in the fourth portion 540.

Claims

1. A power storage element, wherein: It includes a shell, an electrolyte and an electrode body. The shell accommodates the electrolyte and the electrode body. The electrode body comprises a first electrode, a second electrode, a separator and an intermediate 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 between the first electrode and the separator, In a plane orthogonal to the stacking direction of the first electrode and the second electrode, The intermediate film comprises a first region and a second region, The first region includes the center of the interposer in the plane, The second area surrounds the first area. The intermediate film satisfies the following relationship (1): T2<T1 (1), In the formula (1), T1 represents the thickness of the interposer film in the first region, and T2 represents the thickness of the interposer film in the second region.

2. The electric storage element according to claim 1, wherein The storage element has a height direction, a width direction and a thickness direction. The height direction, the width direction and the thickness direction are orthogonal to each other, The thickness direction is parallel to the stacking direction, In the plane orthogonal to the stacking direction, The first region extends along the width direction, The second region includes a third region and a fourth region, In the height direction, the first region is arranged between the third region and the fourth region, The interposer further satisfies the following relationship (2): T3<T4 (2), In the formula (2), T3 represents the thickness of the interposer film in the third region, and T4 represents the thickness of the interposer film in the fourth region.

3. The electric storage element according to claim 2, wherein: The interposer further satisfies the following relationships (3) and (4): 10μm≤T1≤20μm (3), T3≤3μm (4).

4. The electric storage element according to claim 2, wherein: The interposer is formed on a surface of at least one of the first electrode and the separator. The intermediate membrane is porous, and The intermediate membrane comprises inorganic particles and a binder.

5. The electric storage element according to any one of claims 2 to 4, wherein The partition includes a zigzag portion, In the zigzag portion, the partition is folded into a zigzag shape, At both ends in the height direction, the partition is folded back, and The separator is folded back so as to alternately sandwich the first electrode or the second electrode.

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