Thin film for solid-state battery
By using fibrous crystalline fluorinated resins and controlling the content of volatile components in the thin film for solid-state batteries, the problems of performance degradation and insufficient flexibility caused by residual solvents have been solved, enabling efficient roll-to-roll continuous coating manufacturing and improving the performance and production efficiency of solid-state batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2025-12-02
- Publication Date
- 2026-06-16
AI Technical Summary
In the prior art, the thin films used in solid-state batteries have a large amount of residual solvent during the manufacturing process, which leads to reduced performance. At the same time, it is impossible to achieve roll-to-roll continuous coating method, and the films have insufficient flexibility.
The film design incorporates solid electrolyte particles and crystalline fluorinated resin, wherein the crystalline fluorinated resin is at least partially fibrous, and the volatile content is controlled to be below 10 ppm by mass. It is manufactured by a dry film-forming method and produced using a roll-to-roll continuous coating method.
It effectively reduces the adverse effects of residual solvents on the performance of solid-state batteries, improves the flexibility of the film, achieves efficient roll-to-roll continuous coating, and reduces manufacturing energy consumption and equipment costs.
Smart Images
Figure CN122224933A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to a thin film for solid-state batteries. Background Technology
[0002] Solid-state batteries are secondary batteries that use a solid electrolyte as the electrolyte. Compared with liquid batteries that use only a liquid electrolyte, they have attracted much attention due to their higher performance in terms of charging performance and other aspects. As for the film formation methods of the positive electrode active material layer, solid electrolyte layer, or negative electrode active material layer (hereinafter, these three layers are referred to as thin films for solid-state batteries) contained in such solid-state batteries, a film formation method (slurry film formation method) is generally known, which involves preparing a slurry by containing a solvent in each component and then coating and drying the slurry.
[0003] However, slurry film formation methods consume a lot of energy and require a significant amount of equipment due to the drying process. In contrast, solvent-free film formation methods (dry film formation methods) have been proposed.
[0004] For example, Patent Document 1 discloses a positive electrode for a secondary battery, characterized by having a positive electrode active material layer comprising at least a positive electrode active material and a solid electrolyte. The oil absorption amount, determined by the amount of linseed oil absorbed within and between primary particles of the positive electrode active material, is 35-50 ml per 100g. The average particle size of the solid electrolyte particles is 1.5-2.5 μm. The positive electrode active material layer is formed by mixing the positive electrode active material particles and the solid electrolyte particles in a solvent-free environment and then pressing the mixture into shape. According to Patent Document 1, a positive electrode for a secondary battery with high capacity retention, a method for manufacturing the positive electrode for a secondary battery, and an all-solid-state secondary battery incorporating the positive electrode can be provided.
[0005] Existing technical documents
[0006] Patent documents
[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-143133 Summary of the Invention
[0008] The inventors have discovered that the presence of a large amount of residual solvent in the thin film for solid-state batteries leads to a decrease in the performance of the solid-state battery. In contrast, by using a dry film-forming method, as described in Patent Document 1, to fabricate the thin film for solid-state batteries, the amount of residual solvent in the solid-state battery film can be reduced.
[0009] However, in order to form battery films with efficient manufacturing processes and low cost, it is necessary to use roll-to-roll continuous coating methods to manufacture solid battery films, just like existing methods. However, in dry film formation based on intermittent pressure molding, as in Patent Document 1, there are problems such as low flexibility of solid battery films and the inability to realize roll-to-roll continuous coating methods.
[0010] Therefore, the purpose of this disclosure is to provide a thin film for solid-state batteries that, due to its low content of residual solvent, is less likely to adversely affect the performance of the solid-state battery and can be manufactured using a roll-to-roll continuous coating method.
[0011] This disclosure achieves the above objectives through the following means.
[0012] <Method 1>
[0013] A thin film for a solid-state battery comprises solid electrolyte particles and a crystalline fluorinated resin that binds the solid electrolyte particles together, wherein at least a portion of the crystalline fluorinated resin is fibrous and the content of volatile components, as determined by a gas analysis method, is less than 10 ppm by mass.
[0014] <Method 2>
[0015] The solid-state battery film according to Method 1, wherein the content of the volatile component is less than 1 ppm by mass.
[0016] Method 3
[0017] The thin film for solid batteries according to method 1 or 2, wherein the particle size of the solid electrolyte particles is 1.0 μm or less.
[0018] Method 4
[0019] The solid-state battery film according to any one of methods 1 to 3, wherein the content of the crystalline fluorine resin is 1.0% by mass or less.
[0020] <Method 5>
[0021] The solid-state battery film according to any one of methods 1 to 4, wherein the content of the crystalline fluorine resin is 0.6% by mass or more.
[0022] <Method 6>
[0023] The solid battery film according to any one of embodiments 1 to 5, wherein the solid electrolyte particles are sulfide solid electrolyte particles.
[0024] <Method 7>
[0025] The solid-state battery film according to any one of embodiments 1 to 6, wherein the crystalline fluorine resin is polytetrafluoroethylene, perfluoroalkyl compound, polyfluoroalkyl compound or a combination thereof.
[0026] Method 8
[0027] The thin film for a solid battery according to any one of embodiments 1 to 7 is a positive electrode active material layer that further contains a positive electrode active material.
[0028] <Method 9>
[0029] The thin film for a solid battery according to any one of embodiments 1 to 7 is a solid electrolyte layer.
[0030] <Method 10>
[0031] The thin film for a solid battery according to any one of embodiments 1 to 7 is a negative electrode active material layer that further contains a negative electrode active material.
[0032] <Method 11>
[0033] A solid-state battery has a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in sequence, wherein at least one layer selected from the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is a thin film for a solid-state battery as described in any one of embodiments 1 to 7.
[0034] According to this disclosure, a thin film for solid-state batteries can be provided, which can be manufactured using a roll-to-roll continuous coating method by minimizing the content of residual solvent, thus avoiding adverse effects on the performance of the solid-state battery. Attached Figure Description
[0035] Figure 1 This is a cross-sectional schematic diagram used to illustrate the thin film for solid-state batteries disclosed herein.
[0036] Figure 2 This is a cross-sectional schematic diagram used to illustrate the solid-state battery of this disclosure.
[0037] Symbol Explanation
[0038] 100 Thin film for solid-state batteries
[0039] 110 Solid electrolyte particles
[0040] 120 Crystalline Fluorine Resin Particles
[0041] 130 Crystalline Fluorine Resin Fiber
[0042] 200 solid-state batteries
[0043] 210 Positive electrode active material layer
[0044] 220 Solid electrolyte layer
[0045] 230 Negative Electrode Active Material Layer Detailed Implementation
[0046] Thin films for solid-state batteries
[0047] The thin film for solid-state batteries disclosed herein comprises solid electrolyte particles and a crystalline fluorinated resin that binds the solid electrolyte particles together. At least a portion of the crystalline fluorinated resin is fibrous, and the content of volatile components, as determined by a gas analysis method, is less than 10 ppm by mass.
[0048] According to this disclosure, a thin film for solid-state batteries can be provided, which can be manufactured using a roll-to-roll continuous coating method by minimizing the content of residual solvent, thus avoiding adverse effects on the performance of the solid-state battery.
[0049] Because many residual solvents, i.e. volatile components, remain in the thin films used in solid-state batteries, there is a possibility of reduced performance in solid-state batteries. Although there is no theoretical limitation, it is believed that this is because some of the particles contained in the thin films used in solid-state batteries, such as solid electrolyte particles, are coated with decomposition products of volatile components.
[0050] In contrast, the present inventors have discovered that when the content of volatile components in the thin film for solid-state batteries is less than 10 ppm by mass, the performance degradation of the solid-state battery can be suppressed, and the physical properties preferred for use as a solid-state battery can be obtained.
[0051] Furthermore, by using a crystalline fluorinated resin as a binder in the film for solid-state batteries, high flexibility can be achieved after film formation. Although not theoretically limited, it is believed that this is because applying shear force to the crystalline fluorinated resin can cause it to become fibrous, promoting the adhesion between solid electrolyte particles and thus improving flexibility.
[0052] Specifically, for example, such as Figure 1 As shown, the solid-state battery film 100 of this disclosure includes solid electrolyte particles 110, crystalline fluorinated resin particles 120, and crystalline fluorinated resin fibers 130 formed by fiberizing a portion of the crystalline fluorinated resin particles 120. Furthermore, the solid electrolyte particles 110 are bonded together by the crystalline fluorinated resin particles 120, and also by the crystalline fluorinated resin fibers 130. Therefore, the solid-state battery film 100 has high flexibility.
[0053] The constituent elements of the present invention will be described below.
[0054] In this disclosure, "thin film for solid-state batteries" refers to the positive electrode material layers, solid electrolyte layer, or negative electrode active material layer contained in a solid-state battery. The thin film for solid-state batteries disclosed herein can be applied to one or more of these layers.
[0055] In this disclosure, "solid-state battery" refers to a battery that uses at least solid electrolyte particles as the electrolyte. Therefore, a solid-state battery can use a combination of solid electrolyte particles and liquid electrolyte as the electrolyte. Alternatively, "solid-state battery" in this disclosure can also be an all-solid-state battery, i.e., a battery that uses only solid electrolyte particles as the electrolyte.
[0056] The film comprises solid electrolyte particles and a crystalline fluorinated resin that binds the solid electrolyte particles together. The crystalline fluorinated resin functions as a binder, and the solid electrolyte particles are bonded together through the crystalline fluorinated resin, thereby enabling the film for solid-state batteries to have high flexibility.
[0057] The content of crystalline fluorinated resin is not particularly limited, and can be less than 1.0% by mass, less than 0.9% by mass, or less than 0.8% by mass relative to the film used in solid-state batteries. Additives that hinder the contact between solid electrolyte particles and reduce lithium-ion conductivity are important factors that negatively impact the performance of solid-state batteries. Therefore, when a solid-state battery film contains a large amount of crystalline fluorinated resin to improve its flexibility, ionic conductivity decreases.
[0058] The content of crystalline fluorinated resin is not particularly limited, but from the viewpoint of ensuring the flexibility of the film for solid-state batteries, it is preferably 0.6% by mass or more or 0.7% by mass or more relative to the film for solid-state batteries.
[0059] There is no particular limitation on the content of solid electrolyte particles; it can be appropriately determined based on the application and performance of the film for solid-state batteries. For example, the content of solid electrolyte particles can be 1% or more by mass, 5% or more by mass, 10% or more by mass, 15% or more by mass, or 20% or more by mass, or it can be less than 90% by mass, less than 80% by mass, less than 70% by mass, less than 60% by mass, or less than 50% by mass.
[0060] Solid electrolyte particles and particles other than solid electrolyte particles contained in the solid battery film can be bonded together by a crystalline fluorine resin, and particles other than solid electrolyte particles contained in the solid battery film can be bonded together by a crystalline fluorine resin. Examples of particles other than solid electrolyte particles contained in the aforementioned solid battery film include positive electrode active material, negative electrode active material, conductive additives, etc.
[0061] The volatile component content of the thin film for solid-state batteries disclosed herein, as determined by gas analysis methods, is 10 ppm by mass or less. From the viewpoint of preventing degradation of battery performance, a lower volatile component content is preferable. The aforementioned content can be 8 ppm by mass or less, 6 ppm by mass or less, 4 ppm by mass or less, 2 ppm by mass or less, or 1 ppm by mass or less. Alternatively, the aforementioned content can be 1 ppb or more, 10 ppb or more, or 100 ppb or more. Here, when multiple volatile components are present, the aforementioned content refers to the content of each volatile component.
[0062] The content of volatile components was determined using gas analysis methods. These methods involved installing a heating element in a mass spectrometer (GC / MS-QP2010, manufactured by Shimadzu Corporation) and employing temperature-programmed desorption-mass spectrometry (TPD-MS) for both qualitative and quantitative analysis of the target solvent. It should be noted that helium was used as the carrier gas, and the temperature was raised to 250°C at a rate of 10°C / min using the heating element.
[0063] In this specification, "volatile components" refers to solvents used in the manufacturing process of solid-state battery films and components that remain in the solid-state battery films. Examples of solvents include alcohols such as methanol, ethanol, propanol, and butanol; aliphatic hydrocarbons such as hexane and heptane; ketones such as acetone, methyl ethyl ketone, and 2-pentanone; and esters such as ethyl acetate and butyl acetate.
[0064] There is no particular limitation on the flexibility of the thin film for solid-state batteries, and it can be appropriately determined according to the required performance of the solid-state battery. For flexibility, for example, in a cylindrical mandrel test, when a stack of layers containing the thin film for solid-state batteries is wound around a cylinder, the diameter of the cylinder at which cracks begin to appear in the electrode active material layer can be less than 45 mm, less than 40 mm, less than 35 mm, less than 30 mm, less than 25 mm, or less than 20 mm, or it can be more than 5 mm, more than 10 mm, or more than 15 mm.
[0065] The shape of the thin film for solid-state batteries is not particularly limited; for example, it can be a sheet with a generally planar surface. The thickness of the thin film for solid-state batteries is not particularly limited; for example, it can be 0.1 μm or more, 1 μm or more, or 10 μm or more, or it can be less than 2 mm, less than 1 mm, or less than 500 μm.
[0066] There are no particular limitations on the film formation method for solid-state batteries. From the viewpoint of reducing the content of volatile components in the film for solid-state batteries, it is preferable to use a dry film formation method that does not require volatile components.
[0067] <Solid Electrolyte Particles>
[0068] The particle size of the solid electrolyte particles can be less than 1.0 μm. By reducing the particle size, the flexibility of the thin film for solid-state batteries can be improved. Although there is no theoretical limitation, it is believed that this is because by reducing the particle size of the solid electrolyte particles, the solid electrolyte particles can efficiently apply shear force to the crystalline fluorinated resin during compounding, thereby increasing the amount of fibrous crystalline fluorinated resin. The particle size of the solid electrolyte particles can be less than 0.9 μm, less than 0.8 μm, less than 0.7 μm, or less than 0.5 μm, or greater than 0.1 μm, greater than 0.2 μm, or greater than 0.3 μm.
[0069] Here, the particle size of the solid electrolyte particles is the particle size (median particle size) that represents the cumulative 50% of the particle size distribution on a volume basis, obtained using laser diffraction and scattering methods.
[0070] There are no particular limitations on the solid electrolyte particles; they can be sulfide solid electrolyte particles. Alternatively, solid electrolyte particles can also be oxide solid electrolyte particles or polymer electrolyte particles, etc.
[0071] Examples of sulfide solid electrolyte particles include amorphous sulfide solid electrolyte particles, crystalline sulfide solid electrolyte particles, and sulfide-silver-germanium ore type solid electrolyte particles, but these are not limited to these examples. A specific example of sulfide solid electrolyte particles is the Li₂S-P₂S₅ system (Li₇P₃S₅). 11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2 (Li 13 GeP3S 16 Li 10 GeP2S 12 etc.), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7－x PS 6－x Cl x etc.; or combinations thereof, but not limited to these.
[0072] Examples of oxide solid electrolyte particles include Li7La3Zr2O. 12 Li 7－x La3Zr 1－x Nb x O 12 Li 7－3x La3Zr2Al x O 12 Li 3x La 2／3－xTiO3, Li 1＋x Al x Ti 2－x (PO4)3, Li 1＋x Al x Ge 2－x (PO4)3, Li3PO4, or Li 3＋x PO 4－x N x (LiPON) etc.; or combinations thereof, but not limited thereto.
[0073] Sulfide solid electrolyte particles and oxide solid electrolyte particles can be glass or crystallized glass (glass ceramic).
[0074] Examples of polymer electrolyte particles include polyethylene oxide (PEO), polypropylene oxide (PPO), and their copolymers, but are not limited to these.
[0075] <Crystall Fluorine Resins>
[0076] At least a portion of the crystalline fluorinated resin is fibrous. By making the crystalline fluorinated resin fibrous, the adhesion between solid electrolyte particles can be improved, resulting in high flexibility.
[0077] There are no particular limitations on crystalline fluoropolymers; for example, they can be polytetrafluoroethylene (PTFE), perfluoroalkyl compounds, or polyfluoroalkyl compounds. A single crystalline fluoropolymer can be used, or a combination of two or more can be used.
[0078] Perfluoroalkyl compounds can be, for example, perfluorooctane sulfonic acid (PFOS), perfluorooctane acid (PFOA), perfluorohexane sulfonic acid (PFHxS), etc.
[0079] Polyfluoroalkyl compounds can be, for example, polyfluoroalkyl vinyl ethers (PFA), polyfluoroalkyl acrylates (PFAA), etc.
[0080] Crystalline fluoropolymers can contain resins in particle shape. The particle size of crystalline fluoropolymers is not particularly limited and can be 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, 0.2 μm or less, or 0.1 μm or less, or 0.01 μm or more, 0.03 μm or more, or 0.05 μm or more. Here, the particle size of the crystalline fluoropolymer is the particle size (median particle size) representing the 50% cumulative value of the particle size distribution on a volume basis determined using laser diffraction and scattering methods.
[0081] There are no particular limitations on the manufacturing method of fibrous crystalline fluorinated resins. For example, a portion of the crystalline fluorinated resin can be fibrous by mixing particle-shaped crystalline fluorinated resins with solid electrolyte particles while applying shear force.
[0082] <Positive Electrode Active Material Layer>
[0083] The thin film for solid-state batteries can be a positive electrode active material layer that further contains a positive electrode active material. In this case, the positive electrode active material layer at least comprises a positive electrode active material, solid electrolyte particles, and a crystalline fluorine resin, and may further optionally contain conductive additives. For the solid electrolyte particles, refer to the description related to solid electrolyte particles described above; for the crystalline fluorine resin, refer to the description related to crystalline fluorine resins described above. The positive electrode active material layer may contain various other additives.
[0084] The individual contents of the positive electrode active material, solid electrolyte particles, and conductive additives in the positive electrode active material layer can be appropriately determined according to the target battery performance. For example, if the total solid component of the positive electrode active material layer is set to 100% by mass, the content of the positive electrode active material can be 40% or more by mass, 50% or more by mass, 60% or more by mass, or less than 100% by mass or less than 90% by mass.
[0085] (Positive electrode active material)
[0086] There are no particular limitations on the material of the positive electrode active material, as long as it can adsorb and release lithium ions. Examples of positive electrode active materials include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), and lithium nickel-cobalt-manganese oxide (NCM:LiCO3). 1／3 Ni 1／3 Mn 1／3 O2), Lithium nickel cobalt aluminate (LiNi) 0.8 (CoAl) 0.2 O2), Li 1＋x Mn 2－x－y M y O4 (where M is one or more metallic elements selected from Al, Mg, Co, Fe, Ni and Zn) represents the composition of Li-Mn spinel with heteroelemental substitution, but is not limited to this.
[0087] The positive electrode active material is not particularly limited and can have a coating layer. The coating layer is a layer containing a substance that exhibits lithium-ion conductivity, low reactivity with the positive electrode active material and solid electrolyte particles, and maintains a non-flowing coating layer morphology even when in contact with the active material and solid electrolyte particles. Specific examples of materials constituting the coating layer include LiNbO3 and Li4Ti5O4. 12 Examples include Li3PO4, but it is not limited to these.
[0088] The shape of the positive electrode active material is not particularly limited as long as it is the shape commonly used as a positive electrode active material in batteries. The positive electrode active material can be, for example, particulate. It can be primary particles or secondary particles formed by the aggregation of multiple primary particles. The particle size of the positive electrode active material can be, for example, 1 nm or more, 5 nm or more, or 10 nm or more; alternatively, it can be 500 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. It should be noted that the particle size of the positive electrode active material is the particle size (median particle size) representing the 50% cumulative value of the particle size distribution on a volume basis determined by laser diffraction and scattering methods.
[0089] (Conductive additive)
[0090] There are no particular limitations on the conductive additives. Examples of conductive additives include vapor-grown carbon fiber (VGCF), acetylene black (AB), Ketjen black (KB), carbon nanotubes (CNT), and carbon nanofibers (CNF), but these are not limited to these. Conductive additives can be in particle or fibrous form, and their size is not particularly limited. There are no particular limitations on the conductive additives; a single additive can be used, or a combination of two or more can be used.
[0091] <Solid Electrolyte Layer>
[0092] The thin film for solid-state batteries can also be a solid electrolyte layer. In this case, the solid electrolyte layer comprises at least solid electrolyte particles and a crystalline fluorinated resin, and may further optionally contain conductive additives. For details regarding solid electrolyte particles and conductive additives, refer to the descriptions related to conductive additives described above. The solid electrolyte layer may contain various other additives.
[0093] <Negative Electrode Active Material Layer>
[0094] The thin film for solid-state batteries can also be a negative electrode active material layer further containing a negative electrode active material. In this case, the negative electrode active material layer at least comprises a negative electrode active material, solid electrolyte particles, and a crystalline fluorine resin, and may further optionally contain conductive additives. For solid electrolyte particles, refer to the descriptions related to solid electrolyte particles described above; for crystalline fluorine resins, refer to the descriptions related to crystalline fluorine resins described above; for conductive additives, refer to the descriptions related to conductive additives described above. The negative electrode active material layer may contain various other additives.
[0095] The individual contents of the negative electrode active material, solid electrolyte particles, and conductive additives in the negative electrode active material layer can be appropriately determined according to the target battery performance. For example, if the total amount of the negative electrode active material layer (the total amount of solid components) is set to 100% by mass, the content of the negative electrode active material can be 40% or more by mass, 50% or more by mass, or 60% or more by mass, or it can be less than 100% by mass or less than 90% by mass.
[0096] (Negative electrode active material)
[0097] As the negative electrode active material, various materials whose lithium ion absorption and release potential (charge / discharge potential) is lower than that of the positive electrode active material disclosed herein can be used. The material of the negative electrode active material is not particularly limited and can be metallic lithium, or a material capable of absorbing and releasing lithium ions or other metal ions. Examples of materials capable of absorbing and releasing lithium ions or other metal ions include, for example, alloy-based negative electrode active materials, carbon materials, or lithium titanate (Li4Ti5O). 12 (etc.), but not limited to this.
[0098] There are no particular limitations on alloy-based anode active materials; for example, Si alloy-based anode active materials or Sn alloy-based anode active materials can be cited. Si alloy-based anode active materials include silicon, silicon oxides, silicon carbides, silicon nitrides, or their solid solutions. Furthermore, Si alloy-based anode active materials can contain metallic elements other than silicon, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Sn, and Ti. Sn alloy-based anode active materials include tin, tin oxides, tin nitrides, or their solid solutions. Furthermore, Sn alloy-based anode active materials can contain metallic elements other than tin, such as Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, In, Ti, and Si.
[0099] As a carbon material, there are no particular limitations; for example, hard carbon, soft carbon, and graphite can be cited.
[0100] There are no particular limitations on the shape of the negative electrode active material; it can be any shape commonly used as a negative electrode active material in batteries. For example, the negative electrode active material can be in particle form or in sheet form.
[0101] Solid-state batteries
[0102] The solid-state battery disclosed herein has, in sequence, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, wherein at least one layer selected from the aforementioned positive electrode active material layer, the aforementioned solid electrolyte layer, and the aforementioned negative electrode active material layer is a thin film for the solid-state battery disclosed herein.
[0103] According to this disclosure, a solid-state battery comprising a thin film for solid-state batteries can be provided, wherein the thin film for solid-state batteries is less likely to adversely affect the performance of the solid-state battery by having a low content of residual solvent, and can be manufactured using a roll-to-roll continuous coating method.
[0104] The solid-state battery disclosed herein has at least a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in sequence, and may further include a positive electrode current collector layer, a negative electrode current collector layer, and a liquid electrolyte.
[0105] Specifically, for example, such as Figure 1 As shown, the solid-state battery 200 sequentially comprises a positive electrode active material layer 210, a solid electrolyte layer 220, and a negative electrode active material layer 230.
[0106] At least one layer selected from the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is the thin film for solid-state batteries disclosed herein. Two or more of these layers can be the thin film for solid-state batteries disclosed herein. The positive electrode active material layer can be referred to the description related to the positive electrode active material layer described above, the solid electrolyte layer can be referred to the description related to the solid electrolyte layer described above, and the negative electrode active material layer can be referred to the description related to the negative electrode active material layer described above.
[0107] Positive current collector layer
[0108] The material used in the positive electrode current collector layer is not particularly limited, and materials commonly used as positive electrode current collectors in solid-state batteries can be appropriately used. Examples of materials that can be used in the positive electrode current collector layer include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, and stainless steel, but are not limited to these. Furthermore, the positive electrode current collector layer may have a coating layer on its surface for purposes such as adjusting resistance. Alternatively, the positive electrode current collector layer may be formed by depositing or vapor-depositing the aforementioned metals onto a metal foil or substrate.
[0109] The shape of the positive current collector layer is not particularly limited; for example, it can be foil-shaped, plate-shaped, or mesh-shaped. Among these, foil-shaped is preferred. The thickness of the positive current collector layer is not particularly limited; it can be 0.1 μm or more, 1 μm or more, less than 1 mm, or less than 100 μm.
[0110] <Negative current collector layer>
[0111] There are no particular limitations on the materials used in the negative electrode current collector layer; materials commonly used as negative electrode current collectors in solid-state batteries can be appropriately adopted. Examples of materials that can be used in the negative electrode current collector layer include Cu, Ni, Cr, Au, Pt, Ag, Al, Fe, Ti, Zn, Co, stainless steel, or carbon plates, but these are not limited to. The negative electrode current collector layer may have a coating layer on its surface for purposes such as adjusting resistance.
[0112] The shape of the negative electrode current collector layer is not particularly limited; for example, it can be foil-shaped, plate-shaped, or mesh-shaped. Among these, foil-shaped is preferred. The thickness of the negative electrode current collector layer is not particularly limited; it can be 0.1 μm or more, 1 μm or more, less than 1 mm, or less than 100 μm.
[0113] <Liquid Electrolytes>
[0114] There are no particular limitations on liquid electrolytes, but it is preferred that they contain auxiliary salts and solvents.
[0115] Lithium salts, which are auxiliary salts for electrolytes with lithium-ion conductivity, are not particularly limited and can include inorganic lithium salts and organic lithium salts. Examples of inorganic lithium salts include LiPF6, LiBF4, LiClO4, and LiAsF6, but are not limited to these. Examples of organic lithium salts include LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiN(FSO2)2, and LiC(CF3SO2)3, but are not limited to these.
[0116] There are no particular limitations on the solvents used in the electrolyte, and examples include cyclic carbonates and chain carbonates. Examples of cyclic carbonates include ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC), but these are not limited to these. Examples of chain carbonates include dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC), but these are not limited to these. There are no particular limitations on the electrolyte; one type can be used alone, or two or more types can be used in combination.
[0117] Example
[0118] The present disclosure will be specifically described with reference to embodiments and comparative examples, but the present disclosure is not limited thereto.
[0119] Fabrication of Thin Films for Solid-State Batteries
[0120] <Examples 1-4>
[0121] As shown in Table 1, Li2S-P2S5 solid electrolyte particles and crystalline fluorinated resin (PTFE) as a binder were mixed under shear force. The resulting mixture was then formed into a sheet shape by dry film deposition and stamping to produce the solid-state battery films of Examples 1-4.
[0122] <Comparative Example 1>
[0123] As shown in Table 1, Li2S-P2S5 solid electrolyte particles and PVDF as a binder were mixed in a solvent to obtain a slurry. The slurry was then coated and dried using a scraper coating machine to produce a thin film for a solid battery, as described in Comparative Example 1.
[0124] <Determination of Volatile Component Content>
[0125] The amounts of volatile components in the solid-state battery films of Examples 1-4 and Comparative Example 1 were determined by installing a heating device in a mass spectrometer (GC / MS-QP2010, manufactured by Shimadzu Corporation) and performing qualitative and quantitative analysis of the target solvents using temperature-programmed desorption-mass spectrometry (TPD-MS). It should be noted that helium was used as the carrier gas, and the temperature was raised to 250°C at a rate of 10°C / min using the heating device. The measurement results are shown in Table 1.
[0126] "evaluate"
[0127] <Whether solid electrolyte particles deteriorate>
[0128] Whether solid electrolyte particles have deteriorated is confirmed by measuring ionic conductivity and elemental analysis. The evaluation criteria are as follows.
[0129] A: No degradation of solid electrolyte particles was observed through ionic conductivity measurements and elemental analysis.
[0130] B: Deterioration of solid electrolyte particles was observed through ionic conductivity measurements and elemental analysis.
[0131] <Flexibility of Thin Films for Solid-State Batteries>
[0132] The flexibility was evaluated by winding a laminate of the solid-state battery films of Examples 1-4 and Comparative Example 1 onto cylinders with diameters of 40 mm and 50 mm using a cylindrical mandrel test. The evaluation criteria are as follows.
[0133] A: When wound into a cylinder with a diameter of 40mm, the film for solid-state batteries is not damaged and has sufficient flexibility.
[0134] B: When wound onto a cylinder with a diameter of 50 mm, the film for solid-state batteries is not damaged and has sufficient flexibility.
[0135] C: When wound into a cylinder with a diameter of 50mm, the film used in solid-state batteries is damaged and does not have sufficient flexibility.
[0136] The evaluation results are shown in Table 1.
[0137] [Table 1]
[0138]
[0139] Based on Examples 1-4 and Comparative Example 1 in Table 1, it can be understood that when the volatile components contained in the film for solid-state batteries are low, the degradation of the solid electrolyte is not observed, and the film for solid-state batteries does not adversely affect the performance of the solid-state battery.
[0140] According to Examples 1-2 in Table 1, it can be seen that by making the particle size of the solid electrolyte smaller, the amount of fibrous crystalline fluorinated resin is increased, resulting in a solid electrolyte layer with high flexibility. Therefore, it can be understood that a smaller particle size of the solid electrolyte is a more preferred condition.
Claims
1. A thin film for a solid-state battery, comprising solid electrolyte particles and a crystalline fluorine resin binding the solid electrolyte particles together. At least a portion of the crystalline fluoropolymer resin is fibrous, and The content of volatile components determined by gas analysis methods is less than 10 ppm by mass.
2. The thin film for solid-state batteries according to claim 1, wherein, The content of the volatile component is less than 1 ppm by mass.
3. The thin film for solid-state batteries according to claim 1, wherein, The particle size of the solid electrolyte particles is less than 1.0 μm.
4. The thin film for solid-state batteries according to claim 1, wherein, The content of the crystalline fluorinated resin is less than 1.0% by mass.
5. The thin film for solid-state batteries according to claim 1, wherein, The content of the crystalline fluorinated resin is 0.6% by mass or more.
6. The thin film for a solid-state battery according to any one of claims 1 to 5, wherein, The solid electrolyte particles are sulfide solid electrolyte particles.
7. The thin film for a solid-state battery according to any one of claims 1 to 5, wherein, The crystalline fluorinated resin is polytetrafluoroethylene, perfluoroalkyl compounds, polyfluoroalkyl compounds, or combinations thereof.
8. The thin film for solid batteries according to any one of claims 1 to 5, wherein it is a positive electrode active material layer further containing a positive electrode active material.
9. The thin film for a solid battery according to any one of claims 1 to 5, wherein it is a solid electrolyte layer.
10. The thin film for a solid battery according to any one of claims 1 to 5, wherein it is a negative electrode active material layer further containing a negative electrode active material.
11. A solid-state battery, comprising, in sequence, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, wherein at least one layer selected from the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is a thin film for a solid-state battery as described in any one of claims 1 to 5.