Battery

Abstract

To provide a technology for improving battery energy density and preventing an electrode from separating from a collector.SOLUTION: A battery includes a collector, and an electrode component arranged on a surface of the collector. The porosity of the electrode component is greater when it is closer to the surface of the collector.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to batteries.

Background Art

[0002] Batteries have been variously improved to enhance performance. For example, Patent Document 1 discloses a battery including a current collector and an electrode component disposed on the surface of the current collector. In the battery of Patent Document 1, the electrode components are disposed at high density on the surface of the current collector. Thereby, the energy density of the battery is improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the battery of Patent Document 1, the energy density of the battery is improved by disposing the electrode components at high density. However, when the electrode components are disposed at high density on the surface of the current collector, it becomes difficult for the current collector to penetrate into the electrode when pressure is applied to coat the electrode on the current collector. For this reason, it becomes difficult to generate an anchor effect between the electrode and the current collector, and the electrode is likely to peel off from the current collector. Further, if the density of the electrode disposed on the surface of the current collector is lowered to make it difficult for the electrode to peel off from the current collector, the energy density of the battery decreases.

[0005] This specification discloses a technology for improving the energy density of a battery and making it difficult for the electrode to peel off from the current collector.

Means for Solving the Problems

[0006] In an aspect of this technology, the battery includes a current collector and an electrode component disposed on the surface of the current collector. The porosity of the electrode component is larger closer to the surface of the current collector.

[0007] According to this configuration, since the porosity of the electrode component is larger closer to the surface of the current collector, when pressure is applied to coat the electrode on the current collector, the current collector can easily enter the pores of the electrode component. As a result, an anchor effect occurs between the electrode and the current collector, making it difficult for the electrode to peel off from the current collector. Also, since the porosity of the electrode component is larger closer to the surface of the current collector, the porosity of the electrode component becomes smaller in a portion away from the surface of the current collector. Thus, the electrode component becomes denser and the energy density becomes higher as it moves away from the surface of the current collector. Therefore, it is possible to simultaneously improve the energy density of the battery and make it difficult for the electrode to peel off from the current collector.

[0008] In a second aspect of this technology, in the above first aspect, the electrode component may include a first layer disposed on the surface of the current collector and a second layer disposed on the first layer. The electrode component may contain a plurality of particles. The volume fraction of the particles in the first layer may be smaller than the volume fraction of the particles in the second layer.

[0009] According to this configuration, the volume fraction of the particles in the first layer closer to the surface of the current collector is smaller than the volume fraction of the particles in the second layer away from the surface of the current collector. Therefore, the porosity of the electrode component can be suitably increased closer to the surface of the current collector.

[0010] In a third aspect of this technology, in the above second aspect, the volume of the current collector may be larger than the volume of the region where the particles are not disposed in the first layer.

[0011] According to this configuration, when pressure is applied to coat the electrode on the current collector, the current collector can easily enter between the particles of the first layer without gaps. Therefore, it is possible to suppress an increase in the electrical resistance of the first layer.

[0012] In a fourth aspect of the present technology, in the second or third aspect, the elastic modulus of the surface of the current collector may be smaller than the elastic modulus of the particles of the first layer.

[0013] According to this configuration, when the electrode is applied to the current collector, the current collector easily enters between the particles of the first layer.

[0014] In a fifth aspect of the present technology, in any one of the second to fourth aspects, the electrode component may include first particles arranged in the first layer and second particles arranged in the second layer. The first particles may have a first outer diameter. The second particles may have a second outer diameter smaller than the first outer diameter.

[0015] According to this configuration, the volume fraction of particles in the first layer can be suitably made smaller than the volume fraction of particles in the second layer.

[0016] In a sixth aspect of the present technology, in any one of the second to fifth aspects, the electrode component may include first particles arranged in the first layer and second particles arranged in the second layer, and a density of the first particles may be lower than a density of the second particles.

[0017] According to this configuration, the volume fraction of particles in the first layer can be suitably made smaller than the volume fraction of particles in the second layer.

[0018] A seventh aspect of the present technology may be any one of the first to sixth aspects, further comprising a solid electrolyte disposed on the electrode component opposite the current collector, wherein the porosity of the electrode component may be greater closer to the surface of the current collector and greater closer to the surface of the solid electrolyte.

[0019] According to this configuration, the porosity of the electrode component increases closer to the surface of the current collector and closer to the surface of the solid electrolyte. This allows not only the current collector but also the solid electrolyte to easily penetrate into the voids of the electrode component when pressure is applied to the current collector, electrode, and solid electrolyte. This creates an anchor effect between the electrode and the solid electrolyte, making the electrode less likely to peel from the solid electrolyte. Furthermore, because the porosity of the electrode component increases closer to the surface of the current collector and the surface of the solid electrolyte, the porosity of the electrode component decreases in areas away from the current collector and the solid electrolyte. This increases the density of the electrode component in areas away from the surface of the current collector and the surface of the solid electrolyte, resulting in a higher energy density. Therefore, even when the battery includes a solid electrolyte, it is possible to simultaneously improve the energy density of the battery and make it less likely for the electrode to peel from the current collector and the solid electrolyte. [Brief explanation of the drawings]

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

[0021] Example 1 The battery 10 of this embodiment will be described. The battery 10 is a secondary battery. As shown in FIG. 1, the battery 10 includes a current collector 12 and an electrode 20.

[0022] The current collector 12 is composed of a metal foil (not shown) and a resin layer (not shown). In this embodiment, the metal foil is a copper foil. Note that the metal foil may be formed of a metal having high conductivity, and may be formed of other metals such as aluminum, nickel, and stainless steel. The resin layer is disposed on the surface of the metal foil. In this embodiment, the resin layer is composed of polyimide, and the battery 10 is used as a negative electrode. An electrode 20 is disposed on the surface (the upper surface in FIG. 1) of the resin layer. That is, the resin layer of the current collector 12 is in contact with the electrode 20. The elastic modulus of the resin layer is smaller than the elastic modulus of the particles 30 (described later) provided in the electrode 20. Further, the volume of the current collector 12 (specifically, the resin layer) is larger than the volume of the region 32 (described later) where the particles 30 (described later) are not disposed in the first layer 22 (described later) of the electrode 20.

[0023] In addition, the resin constituting the resin layer only needs to have an elastic modulus smaller than that of the particles 30 (described later) provided in the electrode 20, and its type is not particularly limited. For example, the resin constituting the resin layer may be polypropylene. Further, the resin layer may be composed of a conductive resin or a non-conductive resin. The conductive resin is, for example, polythiophene. Further, the non-conductive resin can be selected from thermoplastic resins and thermosetting resins. In the case of a non-conductive resin, it is necessary to contain a conductive aid of a carbon material or a metal material. The carbon material has various shapes such as particulate (solid, hollow, porous), fibrous, tubular, brush-shaped, chip-shaped (or flat-shaped), etc., and any of these shapes may be used. The metal material has shapes such as particulate and fibrous, and any of these shapes may be used. Further, the conductive aid can be formed of a metal such as aluminum, nickel, copper, stainless steel, etc., but may be formed of a metal material other than the above. Further, it may be formed of a metal-coated carbon material. Further, when the battery 10 is used as a positive electrode, the resin may be a resin such as a polyvinylidene fluoride (PVdF)-based resin or a polyacrylic acid-based resin. When the battery 10 is used as a negative electrode, the resin may be a resin such as a polyacrylic acid-based resin, polyamideimide, or styrene-butadiene rubber.

[0024] In addition, in this embodiment, the current collector 12 includes a metal foil and a resin layer, but is not limited to such a configuration. The current collector 12 only needs to have an elastic modulus of the substance located on the surface (specifically, the surface on which the electrode 20 is disposed) (the resin constituting the resin layer in the above example) smaller than that of the particles 30 (described later) provided in the electrode 20. For example, the current collector 12 may be composed of only a metal foil or only a resin.

[0025] The electrode 20 is disposed on the surface of the current collector 12 (in this embodiment, the resin layer located on the electrode 20 side of the current collector 12). The electrode 20 includes a plurality of layers. In this embodiment, the electrode 20 includes a first layer 22 disposed on the surface of the current collector 12 and a second layer 24 disposed on the first layer 22.

[0026] The electrode 20 is formed from a slurry containing a plurality of particles 30. For ease of explanation, FIG. 1 illustrates only the particles 30 of the electrode 20. The first layer 22 and the second layer 24 contain the same type of particles 30. In this embodiment, the particles 30 are made of silicon. As described above, the particles 30 contained in the electrode 20 only need to have a higher elastic modulus than the resin layer located on the electrode 20 side of the current collector 12, and the type of particles is not particularly limited. For example, the particles 30 may be made of graphite. When the battery 10 is used as a positive electrode, the particles 30 may be made of a material such as LCO (LiCoO2), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 When the battery 10 is used as a negative electrode, the electrode 20 can be formed of, but is not limited to, NCM-based materials such as O2, LFP (LiFePO4), LiMn2O4, etc. When the battery 10 is used as a negative electrode, the electrode 20 can be formed of, but is not limited to, Si, SiO, graphite, LTO (Li4Ti5O 12 ), etc., but are not limited to these. Furthermore, the particles 30 may be solid particles or porous particles.

[0027] The volume of the particles 30 in the first layer 22 is smaller than the volume of the particles 30 in the second layer 24. Therefore, the volume of the region 32 in the first layer 22 where the particles 30 are not present is larger than the volume of the region in the second layer 24 where the particles 30 are not present. That is, the first layer 22 closer to the current collector 12 has a larger porosity of the electrode component than the second layer 24 farther from the current collector 12. Furthermore, the volume of the region 32 in the first layer 22 where the particles 30 are not present is smaller than the volume of the current collector 12 (in this embodiment, the resin layer located on the electrode 20 side of the current collector 12).

[0028] The battery 10 is manufactured as follows. As shown in FIG. 2( a), first, a first layer 22 is disposed on the surface of the current collector 12. The particles 30 are disposed in the first layer 22 so that the contact area between the particles 30 is small. Specifically, a slurry having a small volume of the particles 30 and many regions where the particles 30 are not present is disposed. The first layer 22 is also disposed so that the volume of the region 32 where the particles 30 are not present in the first layer 22 is smaller than the volume of the resin layer located on the electrode 20 side of the current collector 12. Next, a second layer 24 is disposed on the first layer 22. The particles 30 are disposed in the second layer 24 so that the contact area between the particles 30 is large. Specifically, a slurry having a large volume of the particles 30 and few regions where the particles 30 are not present is disposed. As a result, the first layer 22 and the second layer 24 are formed so that the volume fraction of the particles 30 in the first layer 22 is smaller than the volume fraction of the particles 30 in the second layer 24.

[0029] Next, as shown in FIG. 2( b), the electrode 20 is pressed toward the current collector 12. As described above, the elastic modulus of the particles 30 is greater than that of the resin layer located on the electrode 20 side of the current collector 12. Therefore, when the electrode 20 is pressed toward the current collector 12, the resin layer of the current collector 12 penetrates into the first layer 22 (specifically, the region 32 of the first layer 22 where the particles 30 are not present). For example, in this embodiment, polyimide is used as the resin constituting the resin layer of the current collector 12, and the particles 30 are made of silicon. The Young's modulus of polyimide is 3 to 5 GPa, and the Young's modulus of silicon is 160 to 190 GPa. Therefore, when the electrode 20 is pressed toward the current collector 12, the particles 30 (silicon) are hardly deformed, and the resin layer (polyimide) deforms and penetrates between the particles 30.

[0030] In addition, in this embodiment, since the volume of the particles 30 in the first layer 22 is smaller than the volume of the particles 30 in the second layer 24, the volume fraction of the particles in the first layer 22 is smaller than the volume fraction of the particles 30 in the second layer 24. For example, when the particles 30 are uniformly contained in the entire electrode 20, increasing the volume fraction of the particles 30 makes it difficult for the resin to enter between the particles 30, and the anchor effect generated between the current collector 12 and the electrode 20 becomes smaller. Also, when the volume fraction of the particles 30 is decreased, the density of the electrode component (particles 30) in the electrode 20 decreases, and the energy density of the battery decreases. In this embodiment, by making the volume fraction of the particles 30 in the first layer 22 smaller than the volume fraction of the particles 30 in the second layer 24, the current collector 12 can more easily enter the first layer 22 on the side of the current collector 12 where the volume fraction of the particles 30 is small. On the other hand, since the second layer 24 away from the current collector 12 has a large volume fraction of the particles 30, the density of the electrode component is high, and the energy density of the second layer 24 is improved. Therefore, in the battery 10 of this embodiment, the energy density of the battery 10 is improved, and the electrode 20 is less likely to be peeled off from the current collector 12.

[0031] In addition, in this embodiment, the volume of the region 32 where the particles 30 do not exist in the first layer 22 is smaller than the volume of the resin layer located on the electrode 20 side of the current collector 12. Thereby, when the electrode 20 is pressed toward the current collector 12, it becomes easier for the resin to enter the entire region 32 where the particles 30 do not exist in the first layer 22. For this reason, the resin layer of the current collector 12 can be embedded in the region 32 (void before pressing) where the particles 30 do not exist in the first layer 22, and an increase in the electrical resistance of the first layer 22 can be suppressed.

[0032] (Example 2) In the above-described Example 1, by changing the volume of the particles 30 contained in the first layer 22 and the second layer 24, the volume fraction of the particles 30 in the first layer 22 was made smaller than the volume fraction of the particles 30 in the second layer 24. However, the present invention is not limited to such a configuration. For example, as shown in FIG. 3, by using particles 130a and 130b having different outer diameters, the volume fraction of the particles 130a in the first layer 122 may be made smaller than the volume fraction of the particles 130b in the second layer 124.

[0033] The battery 110 of this example includes a current collector 12 and an electrode 120. In this example, the current collector 12 can be the same as the current collector 12 of Example 1. Therefore, detailed description of the current collector 12 will be omitted.

[0034] The electrode 120 is disposed on the surface of the current collector 12. The electrode 120 includes multiple types of particles 130a and 130b. In this embodiment, the electrode 120 includes two types of particles 130a and 130b (hereinafter, also referred to as first particles 130a and second particles 130b). Specifically, the first layer 122 includes the first particles 130a, and the second layer 124 includes the second particles 130b. The outer diameter of the first particles 130a is larger than the outer diameter of the second particles 130b. The first particles 130a and the second particles 130b may be formed of the same type of material, or may be formed of different types of materials. The type of the first particles 130a is not particularly limited as long as their elastic modulus is greater than the elastic modulus of the substance (e.g., resin) located on the electrode 120 side of the current collector 12. The type of the second particles 130b is also not particularly limited. Furthermore, both the first particles 130a and the second particles 130b may be solid particles, or both may be porous particles.

[0035] The battery 110 is manufactured as follows. First, a first layer 122 is disposed on the surface of the current collector 12. A slurry containing first particles 130a is disposed on the first layer 122. Next, a second layer 124 is disposed on the first layer 122. A slurry containing second particles 130b is disposed on the second layer 124. As described above, the outer diameter of the first particles 130a is larger than the outer diameter of the second particles 130b. Therefore, the volume of the region 132 in the first layer 122 where particles 130a are not present is larger than the volume of the region in the second layer 124 where particles 130b are not present. Therefore, in this embodiment as well, the volume fraction of the first particles 130a in the first layer 122 is smaller than the volume fraction of the second particles 130b in the second layer 124. Therefore, in the battery 110 of this embodiment as well, the energy density of the battery 110 is improved, and the electrode 120 is less likely to peel off from the current collector 12.

[0036] (Example 3) In the above Example 2, by using the first particles 130a and the second particles 130b with different outer diameters, the volume fraction of the first particles 130a in the first layer 122 was made smaller than the volume fraction of the second particles 130b in the second layer 124. However, the configuration is not limited to this. For example, as shown in FIG. 4, by using particles 230a and 230b with different densities, the volume fraction of the particles 230a in the first layer 222 may be made smaller than the volume fraction of the particles 230b in the second layer 224.

[0037] The battery 210 of this example includes a current collector 12 and an electrode 220. In this example, the current collector 12 can be the same as the current collector 12 in the above Examples 1 and 2. Therefore, a detailed description of the current collector 12 is omitted.

[0038] The electrode 220 is disposed on the surface of the current collector 12. The electrode 220 includes a plurality of types of particles 230a and 230b. In this example, it includes two types of particles 230a and 230b (hereinafter also referred to as the first particles 230a and the second particles 230b). Specifically, the first layer 222 contains the first particles 230a, and the second layer 224 contains the second particles 230b. The density of the first particles 230a is smaller than the density of the second particles 230b. The first particles 230a only need to have an elastic modulus greater than the elastic modulus of the material (for example, resin) located on the electrode 220 side of the current collector 12, and their type is not particularly limited. Also, for the second particles 230b, the type is not particularly limited. The outer diameter of the first particles 230a and the outer diameter of the second particles 230b are substantially the same.

[0039] In this embodiment, the amount of first particles 230a contained in the first layer 222 and the amount of second particles 230b contained in the second layer 224 are substantially the same. Furthermore, the first particles 230a and the second particles 230b are formed from the same material, and the first particles 230a have more pores than the second particles 230b. Specifically, the first particles 230a are porous particles, and the second particles 230b are solid particles. Note that both the first particles 230a and the second particles 230b may be porous particles, and the first particles 230a may have more pores than the second particles 230b. Because the first particles 230a have more pores than the second particles 230b, the density of the first particles 230a is lower than the density of the second particles 230b.

[0040] In this embodiment, the density of the first particles 230a contained in the first layer 222 is lower than the density of the second particles 230b contained in the second layer 224. As a result, in this embodiment as well, the volume fraction of the first particles 230a in the first layer 222 is lower than the volume fraction of the second particles 230b in the second layer 224. As a result, in the battery 210 of this embodiment as well, the energy density of the battery 210 is improved and the electrode 220 is less likely to peel off from the current collector 12.

[0041] In this embodiment, the first particles 230a and the second particles 230b are formed from the same material, but this is not a limitation. For example, the first particles 230a and the second particles 230b may be formed from different materials. In this case, two types of particles with different densities may be selected, with the lower-density particles being used as the first particles 230a and the higher-density particles being used as the second particles. The shapes of the first particles 230a and the second particles 230b are also not particularly limited. As long as the density of the electrode components in the entire first layer 222 is lower than the density of the electrode components in the entire second layer 224, the first layer 222 and the second layer 224 may contain electrode components in shapes other than particles. For example, the electrode components in the first layer 222 may be fibrous or may have a porous structure formed by combining multiple solid particles to form pores.

[0042] In addition, in this embodiment, the amount of the first particles 230a contained in the first layer 222 and the amount of the second particles 230b contained in the second layer 224 were substantially the same, but the present invention is not limited to such a configuration. For example, the amount of the first particles 230a contained in the first layer 222 may be made less than the amount of the second particles 230b contained in the second layer 224. In this case, the volume fraction of the first particles 230a in the first layer 222 can be made even smaller than the volume fraction of the second particles 230b in the second layer 224.

[0043] (Example 4) In the above Examples 1 to 3, the batteries 10, 110, and 210 included the current collector 12 and the electrodes 20, 120, and 220, but the present invention is not limited to such a configuration. For example, as shown in FIG. 5(b), the battery 310 may include a solid electrolyte 40 in addition to the current collector 12 and the electrode 320. In this embodiment, the same current collector 12 as that in Examples 1 to 3 above can be used. Therefore, detailed description of the current collector 12 is omitted.

[0044] The electrode 320 is disposed on the surface of the current collector 12. The electrode 320 includes a plurality of layers. In this embodiment, the electrode 320 includes a first layer 322 disposed on the surface of the current collector 12, a second layer 324 disposed on the first layer 22, and a third layer 326 disposed on the second layer 324. The solid electrolyte 40 is disposed on the third layer 326. The solid electrolyte 40 is made of a material containing, for example, lithium or the like.

[0045] The electrode 320 includes a plurality of particles 30, and the same type of particles 30 are included in the first layer 322, the second layer 324, and the third layer 326. The particles 30 in this embodiment can be the same as the particles 30 in Example 1 above. Therefore, detailed description of the particles 30 is omitted. The particles 30 are formed of a material having a higher elastic modulus than the current collector 12 and the solid electrolyte 40.

[0046] The volume fraction of the particles 30 in the first layer 322 is smaller than the volume fraction of the particles 30 in the second layer 324, and the volume fraction of the particles 30 in the third layer 326 is smaller than the volume fraction of the particles 30 in the second layer 324. Since the volume fraction of the particles 30 in the first layer 322 is smaller than the volume fraction of the particles 30 in the second layer 324, the volume of the region 32a where the particles 30 do not exist in the first layer 322 is larger than the volume of the region where the particles 30 do not exist in the second layer 324. That is, in the first layer 322 close to the current collector 12, the porosity of the electrode component is larger than that in the second layer 324 away from the current collector 12. Also, since the volume fraction of the particles 30 in the third layer 326 is smaller than the volume fraction of the particles 30 in the second layer 324, the volume of the region 32b where the particles 30 do not exist in the third layer 326 is also larger than the volume of the region where the particles 30 do not exist in the second layer 324. That is, in the third layer 326 close to the solid electrolyte 40, the porosity of the electrode component is larger than that in the second layer 324 away from the solid electrolyte 40.

[0047] The battery 310 is manufactured as follows. As shown in Fig. 5(a), first, the first layer 322 is disposed on the surface of the current collector 12. In the first layer 322, the particles 30 are arranged so that the contact area between the particles 30 is reduced. Specifically, a slurry with a small volume of the particles 30 and many regions where the particles 30 do not exist is disposed. Also, the first layer 322 is disposed so that the volume of the region 32a where the particles 30 do not exist in the first layer 322 is smaller than the volume of the current collector 12 (for example, the resin layer provided in the current collector 12). Next, the second layer 324 is disposed on the first layer 322. In the second layer 324, the particles 30 are arranged so that the contact area between the particles 30 is increased. Specifically, a slurry with a large volume of the particles 30 and few regions where the particles 30 do not exist is disposed. Thereby, the first layer 322 and the second layer 324 are formed so that the volume fraction of the particles 30 in the first layer 322 is smaller than the volume fraction of the particles 30 in the second layer 324.

[0048] Next, a third layer 326 is disposed on the second layer 324. The particles 30 are arranged in the third layer 326 so that the contact area between the particles 30 is reduced. Specifically, a slurry with a small volume of the particles 30 and many regions where the particles 30 do not exist is disposed. In this embodiment, the same slurry as that used when disposing the first layer 322 is disposed in the third layer 326. Thereby, the third layer 326 is formed such that the volume fraction of the particles 30 in the third layer 326 is smaller than the volume fraction of the particles 30 in the second layer 324. Note that the slurry used when disposing the third layer 326 only needs to have a smaller volume fraction of the particles 30 than the slurry used when disposing the second layer 324, and a slurry having a different volume fraction of the particles 30 from the slurry used when disposing the first layer 322 may be used. Next, a solid electrolyte 40 is disposed on the third layer 326.

[0049] Next, as shown in FIG. 5(b), the current collector 12, the electrode 320, and the solid electrolyte 40 are pressed in the stacking direction (the vertical direction in FIG. 5(b)). When the current collector 12, the electrode 320, and the solid electrolyte 40 are pressed in the stacking direction, the current collector 12 (for example, the resin layer included in the current collector 12) enters the first layer 322 (specifically, the region 32a where the particles 30 do not exist in the first layer 322), and the solid electrolyte 40 enters the third layer 326 (specifically, the region 32b where the particles 30 do not exist in the third layer 326). Therefore, an anchor effect occurs between the current collector 12 and the first layer 322, and an anchor effect occurs between the solid electrolyte 40 and the third layer 326. On the other hand, the volume fraction of the particles 30 in the second layer 324 is larger than the volume fraction of the particles in the first layer 322 and the third layer 326. Therefore, it becomes difficult for the current collector 12 and the solid electrolyte 40 to enter the second layer 324. For this reason, in the second layer 324, the density of the electrode component (the particles 30) increases, and the energy density of the second layer 324 is improved. Therefore, also in the battery 310 of this embodiment, the energy density of the battery 310 is improved, and the electrode 320 is less likely to be peeled off from the current collector 12 and the solid electrolyte 40.

[0050] In this embodiment, the same particles 30 are arranged in the first layer 322, the second layer 324, and the third layer 326, but this configuration is not limited to this. Different types of particles or electrode components may be arranged in the first layer 322, the second layer 324, and the third layer 326. For example, as in Example 2 above, the outer diameter of the particles arranged in the first layer 322 and the third layer 326 may be smaller than the outer diameter of the particles arranged in the second layer 324. Furthermore, as in Example 3 above, the density of the particles arranged in the first layer 322 and the third layer 326 may be smaller than the density of the particles arranged in the second layer 324.

[0051] Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0052] 10, 110, 210, 310: Battery 12: Current collector 20, 120, 220, 320: Electrode 22, 122, 222, 322: 1st layer 24, 124, 224, 324: 2nd layer 30: Particles 32, 32a, 32b, 132, 232: Areas where no particles exist 40: Solid electrolyte 130a, 230a: 1st particle 130b, 230b: 2nd particle

Claims

1. A current collector and, an electrode component disposed on the surface of the current collector, and the battery, wherein the porosity of the electrode component is larger closer to the surface of the current collector.

2. The battery according to claim 1, wherein the electrode component includes a first layer disposed on the surface of the current collector and a second layer disposed on the first layer, the electrode component includes a plurality of particles, and the volume fraction of the particles in the first layer is smaller than the volume fraction of the particles in the second layer.

3. The battery according to claim 2, wherein the volume of the current collector is larger than the volume of the region where the particles are not disposed in the first layer.

4. The battery according to claim 2, wherein the elastic modulus of the surface of the current collector is smaller than the elastic modulus of the particles in the first layer.

5. The battery according to claim 2, wherein the electrode component includes first particles disposed in the first layer and second particles disposed in the second layer, the first particles have a first outer diameter, and the second particles have a second outer diameter smaller than the first outer diameter.

6. The battery according to claim 2, wherein the electrode component includes first particles disposed in the first layer and second particles disposed in the second layer, and the density of the first particles is smaller than the density of the second particles.

7. The battery according to any one of claims 1 to 6, further comprising a solid electrolyte disposed on the side opposite to the current collector of the electrode component, wherein the porosity of the electrode component is larger closer to the surface of the current collector and larger closer to the surface of the solid electrolyte.

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