Current collector and battery

Abstract

The utility model relates to a kind of current collector and the battery with the current collector.The current collector has supporting layer and conductive layer;The supporting layer is the tensile film formed by the resin composition with electrically insulating property;The conductive layer is laminated to the supporting layer;The resin composition includes base material resin and filler;The filler includes particle, and the ratio of the maximum outer diameter of the particle relative to the thickness of the particle is 3 or more.Thereby, the occurrence of battery failure mode of foreign matter through battery can be inhibited.

Description

Technical Field

[0001] This utility model relates to a current collector and a battery. Background Technology

[0002] A prior art electrode plate is disclosed in Japanese Patent Application Publication No. 2024-510696. The electrode plate includes a current collector, an active material layer, and an electrical connection component. The current collector includes a support layer and a conductive layer. The support layer is made of an insulating material. The conductive layer is disposed on one surface of the support layer.

[0003] One of the battery failure modes that has been studied is the penetration of the battery by foreign objects with sharp tips, such as nails. If a foreign object penetrates the battery, a short circuit may occur between the positive and negative electrodes. To suppress the occurrence of short circuits in this mode, current collectors with a support layer made of insulating materials such as resin compositions are being investigated. However, resin compositions are sometimes less strong than metals. Therefore, the battery failure mode of foreign object penetration may itself become more likely to occur. Utility Model Content

[0004] This invention was made in view of the above-mentioned technical problems, and its purpose is to provide a current collector capable of suppressing the occurrence of battery failure modes caused by foreign objects penetrating the battery, and a battery having the current collector.

[0005] The current collector of this utility model includes a support layer and a conductive layer. The support layer is a stretched film composed of a resin composition with electrical insulating properties. The conductive layer is laminated on the support layer. The resin composition includes a base resin and a filler. The filler includes particles. The ratio of the maximum outer diameter of the particles to the thickness of the particles is 3 or more.

[0006] The filler can be made of a material with higher electrical insulation properties than the base resin.

[0007] The particles can be plate-shaped.

[0008] The support layer can be a biaxially stretched membrane.

[0009] The filler can be made of a material with higher electrical insulation properties than the base resin.

[0010] The filler can contain multiple particles.

[0011] Multiple particles can be plate-shaped particles.

[0012] The surfaces of multiple plate-like particles can extend in a direction orthogonal to the thickness direction of the support layer.

[0013] The long axes of multiple plate-like particles can be oriented differently.

[0014] The battery of this utility model has an electrode body and external terminals. The electrode body includes a first electrode, a second electrode, and a separator. The first electrode includes a current collector and an active material layer. The current collector includes a support layer and a conductive layer. The support layer is a stretched film made of a resin composition with electrical insulating properties. The conductive layer is laminated on the support layer. The resin composition includes a base resin and a filler. The filler includes particles. The ratio of the maximum outer diameter of the particles to the thickness of the particles is 3 or more. The active material layer is laminated on the conductive layer. The separator is laminated on the active material layer. The second electrode is laminated on the active material layer through the separator. The external terminals are electrically connected to the conductive layer.

[0015] According to this invention, the occurrence of battery failure modes caused by foreign objects penetrating the battery can be suppressed. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view showing a battery according to one embodiment.

[0017] Figure 2 To observe along the direction of the arrow on line II-II Figure 1 A cross-sectional view of the electrode.

[0018] Figure 3 This is a unfolded view of the first electrode in one embodiment.

[0019] Figure 4 To observe along the direction of the arrow on line IV-IV Figure 3 A partial cross-sectional view of the first electrode.

[0020] Figure 5 This is a partial cross-sectional view showing the first collector together with the foreign object.

[0021] Figure 6 A three-dimensional diagram showing an example of particles contained in a filler. Detailed Implementation

[0022] The current collector and battery of one embodiment of the present invention will be described below with reference to the accompanying drawings. The same or equivalent parts in the drawings are given the same reference numerals and their descriptions will not be repeated.

[0023] Figure 1 This is a cross-sectional view showing a battery according to one embodiment. Figure 1 The battery 1 shown is a so-called prismatic battery. Battery 1 can be a rechargeable secondary battery, such as a lithium-ion battery or a nickel-metal hydride battery. Battery 1 can be used, for example, as a unit included in an energy storage module mounted in an electric vehicle.

[0024] like Figure 1As shown, a battery 1 according to one embodiment of the present invention includes an electrode body 10, a housing 20, a first external terminal 30A, a second external terminal 30B, a first connecting member 40A, and a second connecting member 40B. First, the components of the battery 1 other than the electrode body 10 will be described.

[0025] The housing 20 is conductive. The conductive parts of the housing 20 are made of a metal such as aluminum. The housing 20 houses the electrode body 10. The housing 20 also houses an electrolyte (not shown).

[0026] The housing 20 includes a housing body 21 and a cover 22. The housing body 21 includes a bottom wall 21a and a peripheral wall 21b rising from the bottom wall 21a.

[0027] The cover 22 is joined to the peripheral wall 21b by welding or the like in a manner that closes the opening of the peripheral wall 21b. The cover 22 has a first connecting hole 22a and a second connecting hole 22b.

[0028] The first external terminal 30A and the second external terminal 30B are arranged to be exposed to the outside of the battery 1. The first connecting member 40A and the second connecting member 40B are conductive. At least a portion of the first connecting member 40A and the second connecting member 40B are disposed inside the housing 20.

[0029] The first external terminal 30A or the first connecting member 40A is inserted into the first connecting hole 22a. The first external terminal 30A is electrically connected to the first connecting member 40A. Specifically, the first external terminal 30A and the first connecting member 40A are engaged with each other. The first connecting member 40A is engaged with the electrode body 10. Thus, the first external terminal 30A is electrically connected to the electrode body 10.

[0030] The second external terminal 30B or the second connecting member 40B is inserted into the second connecting hole 22b. The second external terminal 30B is electrically connected to the second connecting member 40B. Specifically, the second external terminal 30B and the second connecting member 40B are engaged with each other. The second connecting member 40B is engaged with the electrode body 10. Thus, the second external terminal 30B is electrically connected to the electrode body 10.

[0031] In this embodiment, the first external terminal 30A is the positive terminal and the second external terminal 30B is the negative terminal. The first external terminal 30A and the second external terminal 30B are arranged in the second direction D2. The second direction D2 is orthogonal to the first direction D1.

[0032] Next, the electrode bodies 10 will be described. The battery 1 according to this embodiment includes a plurality of electrode bodies 10. The battery 1 typically includes two electrode bodies 10. These electrode bodies 10 are arranged in a third direction D3. The third direction D3 is a direction orthogonal to both the first direction D1 and the second direction D2.

[0033] The following description focuses on one of the plurality of electrode bodies 10. Alternatively, each of the plurality of electrode bodies 10 may have the configuration shown below.

[0034] Figure 2 To observe along the direction of the arrow on line II-II Figure 1 A cross-sectional view of the electrode body. (See diagram below.) Figure 1 and Figure 2 As shown, the electrode body 10 includes a first electrode 11A, a second electrode 11B, and a partition 12. The first electrode 11A, the second electrode 11B, and the partition 12 of the electrode body 10 are wound around a winding axis Z. As described above, in this embodiment, the electrode body 10 is a so-called wound electrode body. However, the electrode body 10 may also be a stacked electrode body formed by stacking the first electrode 11A, the second electrode 11B, and the partition 12 in one direction (e.g., the third direction D3). Furthermore, in Figure 2 In the middle, partition 12 is schematically represented by a dashed line.

[0035] The first electrode 11A and the second electrode 11B have a sheet-like shape. The electrode body 10 is composed of an electrode plate assembly formed by winding the first electrode 11A and the second electrode 11B with one or more separators 12 in between. In this embodiment, the first electrode 11A is the positive electrode and the second electrode 11B is the negative electrode. However, it is also possible for the first electrode 11A to be the negative electrode and the second electrode 11B to be the positive electrode.

[0036] A separator 12 is disposed between the first electrode 11A and the second electrode 11B. The separator 12 allows ions to pass between the first electrode 11A and the second electrode 11B while simultaneously separating the two electrodes. The ions are, for example, lithium ions. The separator 12 is electrically insulating.

[0037] Figure 3 This is a developed view of the first electrode in one embodiment. That is, in Figure 3 The image shows the state of the first electrode 11A before it was wound up. Figure 4 To observe along the direction of the arrow on line IV-IV Figure 3 A partial cross-sectional view of the first electrode.

[0038] like Figures 2 to 4 As shown, the first electrode 11A includes a first current collector 100A, a pair of first active material layers 200A, a first protective part 400 and a second protective part 500.

[0039] And, as Figure 4 As shown, the first current collector 100A includes a support layer 110, a first conductive layer 120, a plurality of first tabs 160 and a plurality of second tabs 170.

[0040] The support layer 110 is made of an electrically insulating resin composition. Therefore, the first current collector 100A is a composite current collector composed of conductive and electrically insulating components. Consequently, compared to a case where the first current collector 100A is entirely made of metal, the first current collector 100A is lighter, and the overall safety of the battery 1 is improved. A more detailed description of the support layer 110 will be given later.

[0041] The thickness direction DT of the support layer 110 is approximately orthogonal to the first direction D1. That is, the support layer 110 extends in the first direction D1.

[0042] To reduce the overall thickness of the electrode body 10, the thickness of the support layer 110 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The overall thickness of the support layer 110 is not particularly limited as long as it provides the desired rigidity. For example, a thickness of 2 μm or more is acceptable.

[0043] The first conductive layer 120 is disposed on one side of the support layer 110 in the thickness direction DT. The first conductive layer 120 is stacked on the support layer 110. The first conductive layer 120 may be stacked on the entire surface of one side of the support layer 110.

[0044] The second conductive layer 130 is disposed on the other side in the thickness direction DT. The second conductive layer 130 is stacked on the support layer 110. The second conductive layer 130 may be stacked on the entire surface of the other side of the support layer 110.

[0045] The first conductive layer 120 and the second conductive layer 130 are made of metal. This metal includes, for example, aluminum, copper, nickel, or stainless steel. Typically, the first conductive layer 120 and the second conductive layer 130 are made of a metal containing aluminum. Therefore, the first current collector 100A having the first conductive layer 120 and the second conductive layer 130 is suitable for use as a positive current collector. Alternatively, the first current collector 100A can be a negative current collector, and the first conductive layer 120 and the second conductive layer 130 can be made of a metal containing copper.

[0046] The thicknesses of the first conductive layer 120 and the second conductive layer 130 are thinner than the thickness of the support layer 110. To reduce the overall thickness of the electrode body 10, the thicknesses of the first conductive layer 120 and the second conductive layer 130 are, for example, 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less. To suppress excessive resistance in the first conductive layer 120 and the second conductive layer 130, the thicknesses of the first conductive layer 120 and the second conductive layer 130 are, for example, 0.1 μm or more. Furthermore, when the thicknesses of the first conductive layer 120 and the second conductive layer 130 are 5 μm or less, it is difficult to directly weld the first conductive layer 120 and the second conductive layer 130 together or directly join them by ultrasonic welding.

[0047] The method for forming the first conductive layer 120 and the second conductive layer 130 is not particularly limited. Typically, the first conductive layer 120 and the second conductive layer 130 can be disposed on the support layer 110 by means of vapor deposition or sputtering. The first conductive layer 120 and the second conductive layer 130 can be made of metal films. In this case, the first conductive layer 120 and the second conductive layer 130 can be bonded to the support layer 110 via a resin adhesive.

[0048] like Figure 3 As shown, a plurality of first tabs 160 are arranged in the winding direction DR of the electrode body 10. A plurality of second tabs 170 are arranged in the winding direction DR of the electrode body 10. The plurality of first tabs 160 are separated from each other. The plurality of second tabs 170 are separated from each other. The plurality of second tabs 170 are arranged in a one-to-one correspondence with the plurality of first tabs 160 in the thickness direction DT.

[0049] And, as Figure 2 As shown, a plurality of first electrodes 160 are arranged in the third direction D3. The plurality of first electrodes 160 are joined together by means of ultrasonic bonding or the like. Furthermore, as... Figure 1 As shown, a plurality of first tabs 160 are joined to the first connecting member 40A by means of ultrasonic bonding or the like. Thus, the first external terminal 30A is electrically connected to the first tabs 160. Furthermore, the first external terminal 30A is electrically connected to the first conductive layer 120 and the second conductive layer 130. The configurations of the plurality of first tabs 160 and the plurality of second tabs 170 will be described below.

[0050] The first tab 160 is bonded to the surface of the first conductive layer 120 opposite to the support layer 110 by ultrasonic welding. The first tab 160 is partially bonded to the first conductive layer 120. The first tab 160 extends on the first conductive layer 120 generally along the first direction D1. The first tab 160 extends away from the first conductive layer 120. The extension direction DE of the first tab 160 is generally parallel to the first direction D1. Alternatively, the first tab 160 may also be directly bonded to the first external terminal 30A.

[0051] The second tab 170 is joined to the surface of the second conductive layer 130 opposite to the support layer 110 by ultrasonic welding. The second tab 170 is partially joined to the second conductive layer 130. The second tab 170 extends on the second conductive layer 130 generally along the first direction D1. The second tab 170 extends along the extension direction DE away from the second conductive layer 130. The end of the second tab 170 in the extension direction DE is joined to the first tab 160 by ultrasonic welding. The extension length of the second tab 170 is less than the extension length of the first tab 160.

[0052] The first tab 160 and the second tab 170 are composed of a membrane-like component. The first tab 160 and the second tab 170 are typically composed of a metal membrane containing aluminum or copper, etc.

[0053] The thickness of each of the first tab 160 and the second tab 170 is greater than the thickness of each of the first conductive layer 120 and the second conductive layer 130. The thickness of each of the first tab 160 and the second tab 170 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. These thicknesses are not particularly limited, as long as the desired rigidity is achieved. For example, their thickness can be 2 μm or more.

[0054] A first active material layer 200A of one party is partially stacked on the first conductive layer 120. A second active material layer 200B of the other party is partially stacked on the second conductive layer 130. These first active material layers 200A can be either positive or negative electrode active material layers. These first active material layers 200A are separated from the first tab 160 and the second tab 170. A separator 12 is stacked radially on the first active material layers 200A about the winding axis Z.

[0055] The first active material layer 200A comprises multiple binder particles and multiple active material particles. These multiple active material particles typically each comprise a positive electrode active material. As a positive electrode active material, it may, for example, comprise materials derived from LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li(NiCoMn)O2, Li(NiCoAl)O2, LiFePO4, LiMn... 0.5 Fe 0.5 At least one of the following groups is selected: PO4, LiMnPO4, LiNiPO4, and LiCoPO4. For example, in "Li(NiCoMn)O2", "(NiCoMn)" indicates that the total ratio of the components in parentheses is 1. However, these multiple active material particles may also contain negative electrode active materials such as graphite particles or silicon oxide particles.

[0056] The first protective portion 400 is made of electrically insulating ceramic. The first protective portion 400 covers a portion of the first active material layer 200A, which is stacked on the first conductive layer 120, along its extension direction DE. The first protective portion 400 covers the entire surface of the first conductive layer 120 between the first active material layer 200A and the first tab 160. The first protective portion 400 is also partially disposed between the first conductive layer 120 and the first tab 160 in the thickness direction DT.

[0057] The second protective portion 500 is made of electrically insulating ceramic. The second protective portion 500 covers a portion of the first active material layer 200A, which is stacked on the second conductive layer 130, along its extension direction DE. The second protective portion 500 covers the entire surface of the second conductive layer 130 between the first active material layer 200A and the second tab 170. Furthermore, the second protective portion 500 is also partially disposed between the second conductive layer 130 and the second tab 170 in the thickness direction DT.

[0058] like Figure 2 As shown, the second electrode 11B is stacked on the first active material layer 200A in the aforementioned radial direction, separated by a separator 12. In this embodiment, the electrode body 10 includes multiple separators 12, but may also include a single separator 12.

[0059] The second electrode 11B includes a second current collector 100B and a second active material layer 200B. The second current collector 100B is led out from between the second active material layers 200B to one side in the first direction D1. The second current collector 100B is joined to the second connecting member 40B by ultrasonic welding (see reference). Figure 1 ).

[0060] The second current collector 100B is, for example, made of a metal film. The second current collector 100B is, for example, made of a metal containing copper. Therefore, the second current collector 100B is suitable for use as a negative current collector. Alternatively, if the first current collector 100A is a negative current collector and the second current collector 100B is a positive current collector, the second current collector 100B may be made of a metal containing aluminum. Furthermore, the second current collector 100B may have the same configuration as the first current collector 100A.

[0061] The second active material layer 200B is stacked on both sides of the second current collector 100B. Furthermore, in this embodiment, the second electrode 11B is the negative electrode. Therefore, the second active material layer 200B is a negative electrode active material layer. Alternatively, the second active material layer 200B can also be a positive electrode active material layer.

[0062] The support layer 110 will now be described in detail. As described above, the support layer 110 is composed of an electrically insulating resin composition, and more specifically, is a stretch film composed of an electrically insulating resin composition.

[0063] Figure 5 This is a partial cross-sectional view showing the first collector together with the foreign object. Figure 5 In the middle, used with Figure 4 The same cross-sectional view shows the first collector 100A. Additionally, in Figure 5 For the purpose of explaining the effects described later, the foreign object O, which does not constitute the first current collector 100A, is shown together with the first current collector 100A. For example... Figure 5As shown, the resin composition constituting the stretch film as the support layer 110 comprises a base resin R and a filler. The filler comprises a plurality of particles P.

[0064] Figure 6 A three-dimensional diagram illustrating an example of particles contained in a filler. For example... Figure 6 As shown, in this embodiment, the ratio (aspect ratio) of the maximum outer diameter L of the particle to the thickness h of the particle P is 3 or more. Thus, in this embodiment, the aspect ratio of particle P is relatively large. Therefore, the likelihood of contact between particle P and foreign matter O when it attempts to penetrate the support layer 110 and enter its interior is increased. Therefore, penetration of the support layer 110 caused by foreign matter O can be suppressed. Furthermore, the occurrence of battery 1 failure modes caused by foreign matter O penetrating the battery 1 can be suppressed.

[0065] The support layer 110 will be described in more detail. The support layer 110 is preferably a biaxially stretched film (biaxially stretched film). That is, the support layer 110 is preferably formed by biaxially stretching a resin composition containing a filler and a substrate resin R. By biaxially stretching the resin composition, the long axis of the particles P constituting the filler tends to align in the planar direction of the support layer 110 (the direction orthogonal to the thickness direction DT). Simultaneously, the long axes of the individual particles P tend to align in mutually different directions. Therefore, when a foreign object O attempts to penetrate the support layer 110 and enter the interior of the support layer 110 in the thickness direction DT, the foreign object O more easily contacts the particles P. Thus, the occurrence of battery 1 failure modes where the foreign object O penetrates the battery 1 can be further suppressed. The thinner the support layer 110, the more significant this effect is on the particles P constituting the filler.

[0066] The substrate resin R can be, for example, a polyamide resin, a polyester resin, or a polyolefin resin. To improve rigidity, the substrate resin R is preferably a polyester resin, more preferably polyethylene terephthalate (PET). This maintains the electrical insulation of the support layer 110 and improves the rigidity of the first current collector 100A. Furthermore, the support layer 110 can be made relatively thin.

[0067] like Figure 6As shown, the maximum outer diameter L of particle P can be the maximum outer diameter of the largest face P1 with the largest area among the multiple faces constituting the surface of particle P. The thickness h of particle P can represent the maximum distance between the largest face P1 and its opposite face P2. The aspect ratio can be determined by observation using an optical microscope or an electron microscope. The aspect ratio of particle P can be the average aspect ratio obtained by measuring the aspect ratios of 10 or more particles P contained in the filler and taking the arithmetic mean of these values. The larger the aspect ratio of particle P, the better. The aspect ratio of particle P can be 5 or more or 7 or more. There is no particular upper limit to the aspect ratio of particle P. The aspect ratio of particle P can be 30 or less, 15 or less or 10 or less. The maximum outer diameter L of particle P can be, for example, 2 μm or more and 20 μm or less. The maximum outer diameter L can be smaller or larger than the thickness of the support layer 110.

[0068] There are no particular restrictions on the average particle size of the multiple particles P. The average particle size of the multiple particles P can be less than 10 μm, less than 5 μm, less than 2 μm, or less than 1 μm. The average particle size of the multiple particles P can typically be greater than 0.05 μm or greater than 0.1 μm. This average particle size is the cumulative 50% particle size in the particle size distribution of the volume reference obtained by laser diffraction scattering.

[0069] The particle P can be spherical, plate-shaped, or fibrous, preferably plate-shaped. Therefore, when a foreign object O attempts to penetrate the support layer 110 and enter its interior, the foreign object O is more likely to come into contact with the particle P. This further suppresses the occurrence of battery 1 failure modes where the foreign object O penetrates the battery 1. Furthermore, the particle P can have, for example, a generally circular plate-shaped, rectangular plate-shaped, or polygonal plate-shaped shape.

[0070] The maximum surface P1 of each of the multiple plate-shaped particles P is preferably located in the thickness direction DT of the support layer 110 (see reference). Figure 5 It extends in an orthogonal direction. Therefore, when the foreign object O attempts to penetrate the support layer 110 and enters the interior of the support layer 110 in the thickness direction DT, the foreign object O easily comes into contact with the maximum surface P1 or the opposite surface P2 of the filler particle P. Therefore, it is possible to further suppress the occurrence of battery 1 failure mode where the foreign object O penetrates the battery 1.

[0071] The major axes of the multiple plate-shaped particles P are preferably oriented differently from each other. When the foreign object O attempts to penetrate the support layer 110 and enters the interior of the support layer 110 in the thickness direction DT, the probability of the foreign object O contacting any one of the multiple plate-shaped particles P increases. Therefore, the occurrence of battery 1 failure modes where the foreign object O penetrates the battery 1 can be further suppressed. In addition, the major axis of the particle P can be oriented in the same direction as the length direction of the maximum outer diameter L.

[0072] The filler (particles P) is preferably made of a material with high electrical insulation compared to the base resin R. This improves the mechanical strength of the support layer 110 and further enhances its electrical insulation. Consequently, it further suppresses short circuits inside the battery 1 in battery 1 failure modes where foreign matter O penetrates the battery 1.

[0073] The materials constituting the filler (particle P) can be, for example, inorganic materials, glass materials, and their composites. Specifically, the materials constituting the filler (particle P) can be inorganic oxides such as alumina (Al₂O₃), magnesium oxide (MgO), silicon dioxide (SiO₂), titanium dioxide (TiO₂), and barium titanate (BaTiO₃); nitrides such as aluminum nitride and silicon nitride; metal hydroxides such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide; clay minerals such as mica, talc, boehmite, zeolite, apatite, and kaolin; and glass materials. The filler (particle P) can be prepared using the sol-gel method.

[0074] In the description of the above embodiments, the components that can be combined can also be combined with each other.

[0075] The embodiments disclosed herein should be considered illustrative rather than restrictive in all respects. The scope of this utility model is defined not by the foregoing description but by the technical solutions, and is intended to include all modifications of the same meaning and scope.

Claims

1. A current collector, characterized in that, It has a support layer and a conductive layer; The support layer is a stretch film made of an electrically insulating resin composition; The conductive layer is stacked on the support layer; The resin composition comprises a base resin and a filler; The filler comprises particles, wherein the ratio of the maximum outer diameter of the particles to the thickness of the particles is 3 or more.

2. The current collector according to claim 1, characterized in that, The filler is made of a material with higher electrical insulation properties than the base resin.

3. The current collector according to claim 1, characterized in that, The particles are plate-shaped particles.

4. The current collector according to claim 1, characterized in that, The support layer is a biaxially stretched membrane; The filler is made of a material with higher electrical insulation properties than the base resin; The filler contains a plurality of the particles; The plurality of particles are plate-shaped particles; Each of the plurality of plate-shaped particles extends in a direction orthogonal to the thickness direction of the support layer; The long axes of the multiple plate-shaped particles are oriented differently from each other.

5. A battery, characterized in that, It has an electrode body and external terminals; The electrode body includes a first electrode, a second electrode, and a separator; The first electrode comprises a current collector and an active material layer; The current collector includes a support layer and a conductive layer; The support layer is a stretch film made of an electrically insulating resin composition; The conductive layer is stacked on the support layer; The resin composition comprises a base resin and a filler; The filler comprises particles, wherein the ratio of the maximum outer diameter of the particles to the thickness of the particles is 3 or more; The active material layer is stacked on the conductive layer; The partition is stacked on the active material layer; The second electrode is stacked on the active material layer with the separator in between; The external terminal is electrically connected to the conductive layer.

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