Electrode structure

Abstract

This technology provides a way to make the current collector of an electrode structure less susceptible to damage. [Solution] The electrode structure comprises a current collector and an electrode layer containing a solid electrolyte and disposed on the current collector. The electrode layer comprises a first region disposed on the current collector and a second region disposed on the first region. The first region does not contain the solid electrolyte, and the second region contains the solid electrolyte.

Description

[Technical Field]

[0001] The technology disclosed herein relates to electrode structures, and more particularly to electrode structures for use in batteries. [Background technology]

[0002] Batteries have undergone various improvements to enhance their performance. For example, Patent Document 1 discloses an electrode structure that constitutes the positive and negative electrodes used in a battery. The electrode structure comprises a current collector and an electrode layer placed on the current collector. In the battery of Patent Document 1, an electrolyte is placed between the positive and negative electrodes, which are composed of the electrode structure. In addition, in this type of battery, a solid electrolyte may be included inside the electrode layer of the electrode structure. The inclusion of a solid electrolyte inside the electrode layer facilitates the movement of ions within the electrode layer, thereby improving the performance of the battery. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2019 / 044382 [Overview of the project] [Problems that the invention aims to solve]

[0004] If a solid electrolyte is included within the electrode layer of an electrode structure, ions can easily move within the electrode layer, potentially reaching the current collector. When ions reach the current collector, depending on the type of metal and ions contained in the current collector, an alloying reaction may occur between the metal and ions, potentially damaging the current collector.

[0005] This specification discloses techniques for making the current collectors of electrode structures less susceptible to damage. [Means for solving the problem]

[0006] In a first aspect of this technology, the electrode structure comprises a current collector and an electrode layer comprising a solid electrolyte and disposed on the current collector. The electrode layer comprises a first region disposed on the current collector and a second region disposed on the first region. The first region does not contain the solid electrolyte, while the second region contains the solid electrolyte.

[0007] In this configuration, since the first region of the electrode layer that contacts the current collector does not contain a solid electrolyte, the solid electrolyte contained in the second region is less likely to move to the current collector through the first region. Therefore, damage to the current collector caused by ions that have moved to the current collector via the solid electrolyte can be suppressed.

[0008] In a second aspect of this technology, in the first aspect described above, the solid electrolyte may comprise a first solid electrolyte and a second solid electrolyte of a different type from the first solid electrolyte. The first solid electrolyte may be harder than the second solid electrolyte.

[0009] In this configuration, the second region of the electrode layer contains multiple types of solid electrolytes with different hardnesses. The softer second solid electrolyte can deform and fill the gaps between the components of the electrode layer (e.g., electrode active material) and the harder first solid electrolyte. This improves the ionic conductivity in the second region.

[0010] In a third aspect of this technology, in the second aspect described above, the content of the first solid electrolyte may be greater than the content of the second solid electrolyte.

[0011] In this configuration, the content of the rigid first solid electrolyte increases in the second region. Some rigid solid electrolytes are materials with high ionic conductivity. By increasing the content of the rigid first solid electrolyte, the ionic conductivity in the second region can be improved. [Brief explanation of the drawing]

[0012] [Figure 1] Figure showing the schematic configuration of the electrode structure according to Example 1. [Figure 2] Figure showing the schematic configuration of the electrode structure according to Example 2. [Figure 3] In Example 2, a diagram for explaining the arrangement of the electrode active material, the first solid electrolyte, and the second solid electrolyte included in the second region of the electrode layer.

Mode for Carrying Out the Invention

[0013] (Example 1) Referring to the drawings, the electrode structure 10 of this example will be described. The electrode structure 10 is used as an electrode when manufacturing a battery. As shown in FIG. 1, the electrode structure 10 includes a current collector 12 and an electrode layer 14.

[0014] The current collector 12 is composed of a metal foil. In this example, the metal foil is an aluminum foil, and the electrode structure 10 is used as a negative electrode. Note that the metal foil may be formed of a metal having high conductivity, and may be formed of other metals such as copper, nickel, and stainless steel. Further, the current collector 12 may be a metal-coated resin foil in which the surface of a resin layer (the type of resin is not particularly limited) is coated with a metal (for example, the above metals, etc.).

[0015] The electrode layer 14 is disposed on the current collector 12. The electrode layer 14 contains an electrode active material 20, a conductive assistant 22, and a solid electrolyte 24. The type of the electrode active material 20 is not particularly limited. When the electrode structure 10 is used as a positive electrode, the electrode active material 20 can be formed of LCO (LiCoO2), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and other NCM-based materials, LFP (LiFePO4), LiMn2O4, etc., but is not limited thereto. When the electrode structure 10 is used as a negative electrode, the electrode active material 20 is Si, SiO, graphite, LTO (Li4Ti5O 12) It can be formed by, but is not limited to, these. Also, the electrode active material 20 included in the electrode layer 14 may be of one type, or a plurality of types of electrode active materials may be combined at an arbitrary ratio. Further, the electrode active material 20 may be solid particles, porous particles, or other shapes.

[0016] The conductive assistant 22 is disposed between the electrode active materials 20. The type of the conductive assistant 22 is not particularly limited. For example, the conductive assistant 22 can be formed of a carbon material or a metal material. The carbon materials have various shapes such as particulate (solid, hollow, porous), fibrous, tubular, brush-shaped, chip-shaped (or flat-shaped), etc., and any of them may be used. The metal materials have shapes such as particulate or fibrous, and any of them may be used. Also, metal-coated carbon may be used as the conductive assistant 22. Further, the conductive assistant 22 included in the electrode layer 14 may be of one type, or a plurality of types of conductive assistants may be combined at an arbitrary ratio.

[0017] The solid electrolyte 24 is particulate and is disposed between the electrode active materials 20. However, in this embodiment, the solid electrolyte 24 is not included in the region close to the current collector 12 of the electrode layer 14. Hereinafter, in the electrode layer 14, the region not including the solid electrolyte 24 in the vicinity of the current collector 12 will be referred to as the "first region 16", and the region farther from the current collector 12 than the first region 16 and including the solid electrolyte 24 may be referred to as the "second region 18". The solid electrolyte 24 is formed of a sulfide-based substance. In this embodiment, Li 10 GeP2S 12 (LGPS). Note that the solid electrolyte 24 may be composed of other substances. For example, the solid electrolyte 24 may be composed of other sulfide-based substances such as Li7SiPS8, Li6PS5Cl, etc. Also, the solid electrolyte 24 is Li 0.34 La 0.51 TiO 2.94 (LLT) or Li7La3Zr2O 12It may be composed of oxide-based materials such as (LLZ). Sulfide-based solid electrolytes tend to have higher ionic conductivity than oxide-based solid electrolytes. By using a sulfide-based solid electrolyte 24, the resistance value of the battery manufactured using the electrode structure 10 can be reduced, making it less likely for electrical energy to be lost during charging and discharging.

[0018] In this embodiment, the first region 16 of the electrode layer 14, which is close to the current collector 12, does not contain the solid electrolyte 24. For example, if the solid electrolyte 24 is contained throughout the entire electrode layer 14 (i.e., if the solid electrolyte 24 is contained in both the first region 16 and the second region 18), ions will move more easily between the solid electrolytes 24 throughout the entire electrode layer 14. If the solid electrolyte 24 is contained in the first region 16 and ions move to that solid electrolyte 24, the ions may reach the current collector 12 via the solid electrolyte 24 in the first region 16. This could lead to alloying of the metal (e.g., aluminum) and ions (e.g., lithium ions) that make up the current collector 12, potentially damaging the current collector 12. In this embodiment, the first region 16 of the electrode layer 14, which is close to the current collector 12, does not contain the solid electrolyte 24. Therefore, it becomes more difficult for ions to move to the current collector 12, and damage to the current collector 12 caused by ions moving via the solid electrolyte 24 can be suppressed.

[0019] Here, the manufacturing method of the electrode structure 10 will be described. First, the first region 16 of the electrode layer 14 is coated onto the current collector 12. Specifically, a slurry is prepared by mixing the electrode active material 20 and the conductive additive 22 with a solvent. As mentioned above, the first region 16 does not contain the solid electrolyte 24, so the solid electrolyte 24 is not mixed into the slurry. The slurry may also contain substances such as binders, thickeners, and dispersants. Next, the slurry is coated onto the current collector 12 and dried. This coats the current collector 12 with the first region 16 that does not contain the solid electrolyte 24. Alternatively, the slurry may be coated onto a base (not shown), dried, and then the base may be inverted and pressure applied to the current collector 12 to coat (adhere) the first region 16 onto the current collector 12.

[0020] Next, the second region 18 is coated onto the first region 16 of the electrode layer 14. Specifically, a slurry is prepared by mixing the electrode active material 20, the conductive additive 22, and the solid electrolyte 24 with a solvent. The slurry may also contain additives such as a binder, thickener, and dispersant. Then, the slurry is coated onto the first region 16 coated on the current collector 12 and dried. This produces an electrode structure 10 in which the current collector 12, the first region 16 without the solid electrolyte 24, and the second region 18 containing the solid electrolyte 24 are stacked in order. Alternatively, the slurry may be coated onto a base (not shown), dried, and then the base may be inverted and pressure applied to the first region 16 to coat (adhere) the second region 18 onto the first region 16.

[0021] (Example 2) In the above-described embodiment 1, only one type of solid electrolyte 24 was placed in the second region 18 of the electrode layer 14, but the configuration is not limited to this. For example, as shown in Figure 2, multiple types of solid electrolytes 24 and 26 may be placed in the second region 118 of the electrode layer 14.

[0022] The electrode structure 110 of this embodiment comprises a current collector 12 and an electrode layer 114. The electrode layer 114 contains an electrode active material 20, a conductive additive 22, and solid electrolytes 24 and 26. The electrode layer 114 is composed of a first region 16 near the current collector 12 and a second region 118 further away from the current collector 12 than the first region 16. The first region 16 does not contain solid electrolytes 24 and 26, while the second region 118 contains solid electrolytes 24 and 26. In this embodiment, the current collector 12 and the first region 16 have the same configuration as the current collector 12 and the first region 16 of Embodiment 1 described above, so a detailed explanation is omitted.

[0023] The second region 118 contains several different types of solid electrolytes 24 and 26. In this embodiment, it contains two types of solid electrolytes 24 and 26 (hereinafter also referred to as the first solid electrolyte 24 and the second solid electrolyte 26). The first solid electrolyte 24 and the second solid electrolyte 26 are particulate, and the first solid electrolyte 24 is harder than the second solid electrolyte 26. Furthermore, the second region 118 contains more of the first solid electrolyte 24 than the second solid electrolyte 26.

[0024] In this example, the first solid electrolyte 24 is crystalline Li 10 GeP2S 12 It is composed of (LGPS), and the second solid electrolyte 26 is composed of glassy 75Li2S-25P2S5. 10 GeP2S 12 The Young's modulus of (LGPS) (first solid electrolyte 24) is approximately 37 GPa, and the Young's modulus of 75Li2S-25P2S5 (second solid electrolyte 26) is approximately 24 GPa, Li 10 GeP2S 12 (LGPS) (first solid electrolyte 24) is harder than 75Li2S-25P2S5 (second solid electrolyte 26). Furthermore, as long as the first solid electrolyte 24 is harder than the second solid electrolyte 26, the combination of the first solid electrolyte 24 and the second solid electrolyte 26 is not particularly limited. Also, the first solid electrolyte 24 and the second solid electrolyte 26 may be composed of sulfide-based materials or oxide-based materials.

[0025] Because the first solid electrolyte 24 is harder than the second solid electrolyte 26, the first solid electrolyte 24 is difficult to deform, while the second solid electrolyte 26 is easily deformed. Because the first solid electrolyte 24 is difficult to deform, a gap may occur between the electrode active material 20 and the first solid electrolyte 24 within the electrode layer 114 (specifically, the second region 118). In this embodiment, the second region 118 includes the second solid electrolyte 26 together with the first solid electrolyte 24. Then, as shown in Figure 3, within the electrode layer 114 (specifically, the second region 118), the second solid electrolyte 26 may be deformed by the load from the electrode active material 20 and the first solid electrolyte 24. By deforming the second solid electrolyte 26, the gap that occurs between the electrode active material 20, the first solid electrolyte 24 and the second solid electrolyte 26 can be reduced. Therefore, the ionic conductivity within the electrode layer 114 (specifically, the second region 118) can be improved.

[0026] Furthermore, in this embodiment, the second region 118 contains more of the first solid electrolyte 24 than the second solid electrolyte 26. Generally, harder solid electrolytes tend to have higher ionic conductivity than softer solid electrolytes. For example, Li 10 GeP2S 12 The lithium-ion conductivity of (LGPS) (Solid Electrolyte 24) is approximately 1.2 × 10⁻⁶. -2 The conductivity is S / cm, and the lithium-ion conductivity of 75Li2S-25P2S5 (second solid electrolyte 26) is approximately 3.4 × 10⁻⁶. -4 S / cm, Li 10 GeP2S 12 The lithium-ion conductivity of (LGPS) (first solid electrolyte 24) is higher than that of 75Li2S-25P2S5 (second solid electrolyte 26). By having more of the first solid electrolyte 24 than the second solid electrolyte 26 in the second region 118, the ionic conductivity within the electrode layer 114 (specifically, the second region 118) can be improved. By improving the ionic conductivity within the electrode layer 114 (specifically, the second region 118) in this way, the resistance value of the battery manufactured using the electrode structure 110 can be reduced, making it less likely for electrical energy to be lost during charging and discharging.

[0027] The specific examples of the technology disclosed herein have been described in detail above, but these are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples described above. Furthermore, the technical elements described herein or in the drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated herein or in the drawings achieves multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of symbols]

[0028] 10, 110: Electrode structure 12: Current collector 14, 114: Electrode layer 16:First area 18, 118: 2nd area 20: Electrode active material 24: Solid electrolyte (first solid electrolyte) 26:Second solid electrolyte

Claims

1. Current collector and, It comprises an electrode layer containing a solid electrolyte and disposed on the current collector, The electrode layer comprises a first region disposed on the current collector and a second region disposed on the first region. The first region does not contain the solid electrolyte, The second region is an electrode structure containing the solid electrolyte.

2. The electrode structure according to claim 1, The solid electrolyte comprises a first solid electrolyte and a second solid electrolyte of a different type from the first solid electrolyte. The first solid electrolyte is an electrode structure that is harder than the second solid electrolyte.

3. The electrode structure according to claim 2, An electrode structure in which the content of the first solid electrolyte is greater than the content of the second solid electrolyte.

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