Electrolyte coatings, solid-state batteries, and power consumption devices

Abstract

The present invention provides electrolyte coatings, solid-state batteries, and power consumption devices. [Solution] The electrolyte coating is applied to the surface of a solid electrolyte, which comprises one or both of a sulfide electrolyte and a halide electrolyte. The electrolyte coating is a copolymer of perfluorohexylethyl methacrylate and butyl methacrylate. The present invention significantly improves the stability in air (even at high humidity) without significantly affecting conductivity by applying the electrolyte coating to the surface of sulfide electrolytes and halide electrolytes.

Description

[Technical Field]

[0001] Embodiments of the present invention relate to the field of batteries, and more particularly to electrolyte coatings, solid-state batteries, and power consumption devices. [Background technology]

[0002] With the development of new energy fields, the widespread application of lithium batteries in daily life, and the proliferation of new energy vehicles, improving the safety and energy density of lithium batteries is a pressing need. Conventional organic electrolytes are flammable, explosive, and prone to leakage, posing significant hidden safety risks to lithium batteries. Replacing liquid electrolytes with solid electrolytes is expected to fundamentally solve these hidden safety risks of batteries. Among the various solid electrolytes, sulfide electrolytes and halide electrolytes are considered the two most promising solid electrolyte materials due to their excellent malleability and high ionic conductivity. However, sulfide electrolytes generate toxic gas H2S (hydrogen sulfide) when exposed to air, which can completely destroy the electrolyte structure and degrade its electrochemical performance. Halide electrolytes do not generate toxic gases when in contact with moisture, but the rate of degradation in conductivity and electrical performance is higher than that of sulfide electrolytes. Due to the above problems, the synthesis, storage, transportation, and post-processing of sulfide and halide electrolytes all become heavily dependent on an inert atmosphere or an ultra-low dew point dry room, resulting in a significant increase in production costs, a substantial decrease in work efficiency, and consequently severe limitations on mass production processes.

[0003] In summary, the prior art has the following drawbacks: When sulfide electrolytes are exposed to air, they release the toxic gas H2S, completely destroying their electrolyte structure and degrading their electrochemical performance. When halide electrolytes come into contact with moisture, they undergo hydrolysis, drastically reducing their electrochemical performance. Due to these problems, the synthesis, storage, transportation, and post-processing of sulfide and halide electrolytes all heavily rely on inert atmospheres or ultra-low dew point dry rooms, significantly increasing production costs, drastically reducing work efficiency, and thus severely limiting mass production processes. [Overview of the project] [Problems that the invention aims to solve]

[0004] Surface modification technology solves the problem of sulfide and halide electrolytes being unstable in air, and also solves the problem of their electrochemical performance being reduced by moisture in the air. [Means for solving the problem]

[0005] Some embodiments of the present invention provide an electrolyte coating, which is used as a hydrophobic coating for a solid electrolyte. Specifically, the electrolyte coating is applied to the surface of a solid electrolyte, which comprises one or both of a sulfide electrolyte and a halide electrolyte. In this case, the electrolyte coating is a copolymer of perfluorohexylethyl methacrylate and butyl methacrylate. Normally, sulfide electrolytes and halide electrolytes are unstable in air, and the present invention significantly improves their stability in air (even at high humidity) without significantly affecting conductivity by surface modification technology, i.e., by modifying (coating) the surface of the sulfide electrolyte and halide electrolyte.

[0006] In some embodiments, the molar ratio of perfluorohexylethyl methacrylate to butyl methacrylate is 1 to 8:1, optionally 2 to 6:1, and further optionally 4:1. When the molar ratio of perfluorohexylethyl methacrylate to butyl methacrylate is within the range of 1 to 8:1, it gives the solid electrolyte preferable water resistance, and both the conductivity retention rate and the capacity of the solid battery are high, and the performance at 4:1 is optimal. If the amount of perfluorohexylethyl methacrylate is excessively small (for example, less than 1), the water resistance of the corresponding electrolyte coating is very poor and the conductivity retention rate is poor. Conversely, if the amount of perfluorohexylethyl methacrylate is excessively large (for example, greater than 8), the influence on the absolute value of the conductivity is excessively large and the capacity is low.

[0007] In some embodiments, the thickness of the electrolyte coating is 20 nm to 100 nm, and optionally may be 50 nm. This is because when the thickness of the electrolyte coating is within the range of 20 nm to 100 nm, it does not affect the conductivity of the solid battery, and the conductivity retention rate and the capacity of the solid battery are high, and the performance is optimal when the thickness of the electrolyte coating is 50 nm. If the coating is excessively thin (for example, less than 20 nm), the hydrophobicity of the electrolyte coating is poor and the conductivity retention rate of the solid battery is deteriorated. Conversely, if the coating is excessively thick (for example, thicker than 100 nm), the influence on the absolute value of the conductivity of the all-solid battery is excessively large and the capacity may be low.

[0008] In some specific embodiments, the sulfide electrolyte may be a commercially available conventional sulfide electrolyte, such as Li 7-x PS 6-x Cl x (0 < x < 2), Li 7-x PS 6-x Br x (0 < x < 2), etc., and includes one or more of them but is not limited thereto. Also, the halide electrolyte may be a commercially available conventional halide electrolyte and includes one or more of Li3InCl6, Li3YCl6, Li2ZrCl6, etc., but is not limited thereto.

[0009] Some further embodiments of the present invention provide a solid-state battery comprising a positive electrode sheet, a negative electrode sheet, and a solid electrolyte, wherein the surface of the solid electrolyte is coated with the electrolyte coating described above.

[0010] Some other embodiments of the present invention provide a power consumption device that includes the above-mentioned solid-state battery. [Effects of the Invention]

[0011] By using the electrolyte coating provided by the present invention, the stability of sulfide electrolytes and halide electrolytes in air (even at high humidity) is significantly improved without greatly affecting their conductivity, and the conductivity retention rate and capacity of solid-state batteries are further increased. [Modes for carrying out the invention]

[0012] This invention significantly improves the stability of sulfide electrolytes and halide electrolytes in air (even at high humidity) without significantly affecting their conductivity, by modifying the surfaces of sulfide electrolytes and halide electrolytes with an electrolyte coating. In this invention, the structure of the electrolyte coating is a copolymer of perfluorohexylethyl methacrylate and butyl methacrylate.

[0013] Specifically, the present invention provides an electrolyte coating. The electrolyte coating is used for the hydrophobic coating of a solid electrolyte. Specifically, the electrolyte coating is applied to the surface of the solid electrolyte, and the solid electrolyte contains one or both of a sulfide electrolyte and a halide electrolyte. In the present invention, the electrolyte coating is a copolymer of perfluorohexylethyl methacrylate (A) and butyl methacrylate (B). In the present invention, by means of a surface modification technique, that is, modifying the surfaces of the sulfide electrolyte and the halide electrolyte with the electrolyte coating, the stability in air (even at high humidity) can be significantly improved without significantly affecting the conductivity. In some specific embodiments, the sulfide electrolyte may be a commercially available conventional sulfide electrolyte, such as Li 7-x PS 6-x Cl x (0 < x < 2), Li 7-x PS 6-x Br x (0 < x < 2), etc., including but not limited to one or more of these. Also, the halide electrolyte may be a commercially available conventional halide electrolyte, including but not limited to one or more of Li3InCl6, Li3YCl6, Li2ZrCl6, etc.

[0014] In some embodiments, the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) is 1 to 8:1, optionally 2 to 6:1, and further optionally 4:1. When the molar ratio of perfluorohexylethyl methacrylate to butyl methacrylate is within the range of 1 to 8:1, favorable water resistance is imparted to the solid electrolyte, and both the conductivity retention rate and the capacity of the solid battery are increased, and the performance at 4:1 is optimal. If perfluorohexylethyl methacrylate is excessively low (for example, less than 1), the water resistance of the corresponding electrolyte coating is very poor, and the conductivity retention rate may be poor. Conversely, if perfluorohexylethyl methacrylate is excessively high (for example, greater than 8), the influence on the absolute value of the conductivity is excessively large, and the capacity is reduced.

[0015] In some embodiments, the thickness of the electrolyte coating is 20 nm to 100 nm, and optionally may be 50 nm. This is because when the thickness of the electrolyte coating is within the range of 20 nm to 100 nm, it does not affect the conductivity of the solid-state battery, and both the conductivity retention rate and the capacity of the solid-state battery are high. Moreover, when the thickness of the electrolyte coating is 50 nm, the performance is optimal. If the coating is overly thin (e.g., less than 20 nm), the hydrophobicity of the electrolyte coating is poor, deteriorating the conductivity retention rate of the solid-state battery. Conversely, if the coating is overly thick (e.g., thicker than 100 nm), the influence on the absolute value of the conductivity of the all-solid-state battery is overly large, and the capacity may decrease.

[0016] In addition, some embodiments of the present invention further provide a method for preparing the above-described electrolyte coating, which includes the following steps.

[0017] (1) Method for preparing the electrolyte coating: The electrolyte coating is a copolymer of perfluorohexylethyl methacrylate (A) and butyl methacrylate (B). The raw materials of the copolymer include a polymerizable monomer of perfluorohexylethyl methacrylate (A) and butyl methacrylate (B), an initiator, and a solvent. Among them, the dosage of the initiator may be an amount conventional in the art, preferably 0.1% to 10% of the mass of the polymerizable monomer, more preferably 0.5% to 1.5%, for example, 1% of the mass of the polymerizable monomer. The solvent uses a conventional organic solvent in the art that can dissolve the above polymerizable monomer, such as N,N-dimethylformamide, N,N-dimethylacetamide, etc., and the initiator uses azobisisobutyronitrile (AIBN). Preparation of copolymer: Perfluorohexylethyl methacrylate (A) and butyl methacrylate (B) are mixed in a solvent, an initiator is added, and they are thoroughly stirred and dissolved to form a solution. The solution is frozen with liquid nitrogen and nitrogen is blown in. These two steps are each continued for 30 minutes and repeated alternately three times to remove moisture and air in the system. Then, the reaction solution is stirred and reacted at 80°C in a nitrogen atmosphere for 24 hours to complete the polymerization. Thereafter, the copolymer solution is poured into a large amount of diethyl ether to precipitate the copolymer and at the same time remove unreacted monomer impurities and the like. Then, the product is dried in a vacuum oven at 80°C for 24 hours. Among them, the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) is (1 to 8):1, optionally (2 to 6):1, and further optionally 4:1.

[0018] (2) Surface modification of solid electrolyte Since the electrolyte coating of the copolymer prepared above has a relatively low melting point (60°C), the copolymer may be heated (about 80°C) and sprayed onto the surface of a sulfide electrolyte or a halide electrolyte. Among them, the sulfide electrolyte or the halide electrolyte may be applied by adopting a conventional wet coating or dry coating, and the thickness of the electrolyte coating is 20 to 100 nm, and 50 nm is preferred.

[0019] Some embodiments of the present invention further provide a solid battery including a positive electrode sheet, a negative electrode sheet, and a solid electrolyte modified with the above-described electrolyte coating.

[0020] Positive electrode sheet The positive electrode sheet comprises a positive electrode active material layer coated on a positive electrode current collector, a positive electrode conductive agent, and a positive electrode binder, etc. The manufacturing method of the positive electrode sheet and the ratios between each component may be set according to conventional ratios, and the present invention is not limited thereto. The positive electrode conductive agent is a mixture of one selected from carbon black, acetylene black, graphene, carbon nanotubes, carbon nanofibers, etc., or two or more of these in any proportion. The positive electrode binder is selected from PVDF and its derivatives. The positive electrode active material is a positive electrode active material coated on a positive electrode current collector as is commonly understood in the art. In some embodiments, the type of positive electrode active material may be one or more of lithium iron phosphate (LFP), lithium iron-manganese phosphate (LMFP), lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium manganese oxide (LMO), lithium nickel-manganese oxide (LNMO), lithium nickel-cobalt-manganese oxide (NCM), or lithium nickel-cobalt-aluminum oxide (NCA). Optionally, the positive electrode material is lithium nickel-cobalt-manganese oxide (NCM). In some embodiments, the positive electrode current collector may be aluminum foil.

[0021] Negative electrode sheet The negative electrode sheet comprises a negative electrode active material layer coated on a negative electrode current collector, a negative electrode conductive agent, and a negative electrode binder. The manufacturing method of the negative electrode sheet and the ratio of each component may be set according to conventional ratios and are not limited herein. The negative electrode active material is a negative electrode active material coated on a negative electrode current collector as is commonly understood in the art. In some embodiments, the type of negative electrode active material may be one or more of graphite, silicon carbide material, silicone material, and pure silicon, and may also be lithium metal and lithium metal alloys. Optionally, the negative electrode material may be nanoscale pure silicon, and the negative electrode current collector may be a copper foil current collector. The negative electrode conductive agent comprises one or more of graphite, graphene, carbon black, carbon fiber, and carbon nanotubes. The negative electrode binder comprises at least one of polytetrafluoroethylene or polyimide.

[0022] solid electrolyte The surface of the solid electrolyte has the electrolyte coating described above. In the present invention, the sulfide electrolyte may be a conventional sulfide electrolyte available on the market, and includes, but is not limited to, lithium phosphorus sulfur chloride, or lithium-rich lithium phosphorus sulfur chloride systems, chlorine-rich lithium phosphorus sulfur chloride systems, lithium phosphorus sulfur bromide, etc. The halide electrolyte may be a commercially available conventional halide electrolyte, and includes, but is not limited to, lithium indium chloride, lithium yttrium chloride, lithium zirconium chloride, etc.

[0023] solid state battery The positive electrode sheet, solid electrolyte, and negative electrode sheet are placed in the jig in order and assembled. After assembly, the solid battery is obtained by applying pressure and tightening the nut at the top of the column to a constant pressure. *The assembly process is completed in a glove box under an argon atmosphere, and the particle sizes of the powders corresponding to the positive electrode sheet, solid electrolyte, and negative electrode sheet are kept constant.

[0024] It should be noted that the solid-state battery manufactured by the above method is a lithium-ion secondary battery. However, the solid-state battery manufactured in this invention may be a sodium-ion secondary battery or a potassium-ion secondary battery.

[0025] Those skilled in the art will understand that the battery manufacturing method described above is merely an example, and that other methods commonly used in the art may be employed without departing from the disclosures of this invention.

[0026] All of the reagents and raw materials used in this invention are commercially available.

[0027] The present invention does not require any special assembly method for the battery described above, and any assembly method well known to those skilled in the art may be used. Furthermore, the above technical solution can be applied not only to commonly used all-solid-state lithium-ion batteries, but also to various power batteries such as all-solid-state sodium-ion batteries and all-solid-state potassium-ion batteries. The above-described solid-state battery can be applied to suitable power-consuming devices, including but not limited to electric vehicles.

[0028] The present invention will be further described below with reference to several examples and comparative examples. [Examples]

[0029] Example 1 (1) Production of solid electrolytes modified by electrolyte coating on the surface: Taking a Li6PS5Cl dry solid electrolyte membrane as an example, an electrolyte coating is prepared on its surface. Method for preparing electrolyte coatings: The electrolyte coating is a copolymer of perfluorohexylethyl methacrylate (A) and butyl methacrylate (B). The raw materials for the copolymer include polymerizable monomers of perfluorohexylethyl methacrylate (A) and butyl methacrylate (B), an initiator, and a solvent. Of these, the amount of the initiator is 1% of the mass of the polymerizable monomer. The solvent is an organic solvent that is common in the art and capable of dissolving the above-mentioned polymerizable monomer, and in this embodiment, N,N-dimethylformamide is used. Preparation of copolymer: Perfluorohexylethyl methacrylate (A) and butyl methacrylate (B) are mixed in a solvent, an initiator is added, and the mixture is stirred thoroughly to dissolve and form a solution. The solution is frozen with liquid nitrogen and nitrogen is blown in. These two steps are repeated alternately for 30 minutes each, three times in total, to remove moisture and air from the system. The reaction mixture is then stirred at 80°C in a nitrogen atmosphere for 24 hours to complete the polymerization. Subsequently, the copolymer solution is poured into a large amount of diethyl ether to precipitate the copolymer and remove unreacted monomer impurities. The product is then dried in a vacuum oven at 80°C for 24 hours. The molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) is 4:1.

[0030] (2) Surface modification of solid electrolytes The electrolyte coating of the copolymer described above is sprayed onto the surface of a Li6PS5Cl dry-type solid electrolyte film by heating. The thickness of this electrolyte coating is 50 nm.

[0031] Positive electrode sheet Manufacturing of positive electrode sheets: LiNi 0.8 Co 0.1 Mn 0.1 O2, Super P (a positive electrode conductive agent), and polyvinylidene fluoride (a positive electrode binder) are mixed in a mass ratio of 98:1:1. N-methylpyrrolidone (a solvent) is added, and the mixture is stirred in a vacuum mixer until it becomes uniformly transparent to obtain a positive electrode slurry. The positive electrode slurry is evenly applied to aluminum foil, the aluminum foil is dried at room temperature, then transferred to an oven for drying, and then cold-pressed and cut to obtain a positive electrode sheet.

[0032] Negative electrode sheet Manufacture of the negative electrode sheet: The negative electrode active material (97% artificial graphite and 3% silicon compound SiOx (0 < x < 2)), Super P as the negative electrode conductive agent, sodium carboxymethyl cellulose (CMC-Na) as the negative electrode thickener, and styrene-butadiene rubber (SBR) as the negative electrode binder are mixed according to a mass ratio of 96:1:1:2. After adding deionized water, it is sufficiently stirred with a vacuum mixer until it becomes uniform to obtain a negative electrode slurry. The negative electrode slurry is evenly coated on a copper foil, which is the negative electrode current collector, dried at room temperature, then transferred to an oven for drying, and then cold-pressed and cut to obtain a negative electrode sheet.

[0033] Solid battery The positive electrode sheet, solid electrolyte, and negative electrode sheet are sequentially placed in a jig for assembly. After assembly, it is pressurized to 100 MPa, and the nut at the top of the column is tightened with a certain pressure to obtain a solid battery. ※ The assembly process is completed in a glove box under an argon atmosphere, and the particle sizes of the powders corresponding to the positive electrode sheet, solid electrolyte, and negative electrode sheet are kept constant.

[0034] Example 2 It is consistent with the manufacturing method of Example 1, and the difference lies in that the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) in Example 2 is 1:1.

[0035] Example 3 It is consistent with the manufacturing method of Example 1, and the difference lies in that the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) in Example 3 is 2:1.

[0036] Example 4 It is consistent with the manufacturing method of Example 1, and the difference lies in that the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) in Example 4 is 3:1.

[0037] Example 5 The manufacturing method is consistent with that of Example 1, the only difference being that the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) in Example 5 is 5:1.

[0038] Example 6 The manufacturing method is consistent with that of Example 1, the only difference being that the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) in Example 6 is 6:1.

[0039] Example 7 The manufacturing method is consistent with that of Example 1, the only difference being that the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) in Example 7 is 7:1.

[0040] Example 8 The manufacturing method is consistent with that of Example 1, the only difference being that the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) in Example 8 is 8:1.

[0041] Example 9 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Example 9 is 20 nm.

[0042] Example 10 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Example 10 is 30 nm.

[0043] Example 11 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Example 11 is 40 nm.

[0044] Example 12 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Example 12 is 60 nm.

[0045] Example 13 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Example 13 is 70 nm.

[0046] Example 14 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Example 14 is 80 nm.

[0047] Example 15 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Example 15 is 90 nm.

[0048] Example 16 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Example 16 is 100 nm.

[0049] Example 17 The manufacturing method is consistent with that of Example 1, the only difference being that the solid electrolyte in Example 17 is Li 5.5 PS 4.5 The key feature is the use of Cl and Li6PS5Br (mass ratio 1:1).

[0050] Example 18 The manufacturing method is consistent with that of Example 1, the only difference being that Li6PS5Br is used as the solid electrolyte in Example 18.

[0051] Example 19 The manufacturing method is consistent with that of Example 1, the only difference being that Li3InCl6 is used as the solid electrolyte in Example 19.

[0052] Example 20 The manufacturing method is consistent with that of Example 1, the only difference being that Li3YCl6 is used as the solid electrolyte in Example 20.

[0053] Example 21 The manufacturing method is consistent with that of Example 1, the only difference being that Li2ZrCl6 is used as the solid electrolyte in Example 21.

[0054] Example 22 The manufacturing method is consistent with that of Example 1, the only difference being that Example 22 uses Li6PS5Cl and Li3InCl6 (mass ratio 1:1) as the solid electrolyte.

[0055] Comparative Example 1 The manufacturing method is consistent with that of Example 1, the only difference being that the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) in Comparative Example 1 is 0.5:1.

[0056] Comparative Example 2 The manufacturing method is consistent with that of Example 1, the only difference being that the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) in Comparative Example 2 is 10:1.

[0057] Comparative Example 3 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Comparative Example 3 is 10 nm.

[0058] Comparative Example 4 The manufacturing method is consistent with that of Example 1, the only difference being that the electrolyte coating thickness in Comparative Example 4 is 200 nm.

[0059] Comparative Example 5 The manufacturing method is consistent with that of Example 1, the only difference being that Comparative Example 5 lacks the electrolyte coating.

[0060] Performance measurement method

[0061] Coating thickness: The coating thickness was measured using a scanning electron microscope (SEM / JEOL JSM7610Fplus).

[0062] Water contact angle measurement: A 10 μL water droplet was placed on the surface of an electrolyte membrane composed of a solid electrolyte, and the contact angle was measured using a DSA-30 droplet shape analysis system (Kruess).

[0063] Ion conductivity retention measurement: The initial conductivity 1 was measured by placing a solid electrolyte membrane in a glove box. After leaving the electrolyte in a dew point environment at -40°C for 24 hours, the conductivity 2 of the electrolyte membrane was measured. The conductivity retention rate is obtained by dividing conductivity 2 by conductivity 1. Ion conductivity was measured by EIS using an electrochemical workstation. An ion-blocking cell was fabricated by placing stainless steel sheets as ion-blocking electrodes on both sides of the electrolyte membrane. The measurement frequency range was 10 6 The ionic conductivity of the electrolyte membrane was calculated using the formula σ = L / (R*A) at a frequency of ~1 Hz and an amplitude of 5 mV. Here, L is the thickness of the electrolyte membrane, A is the effective area of ​​the electrolyte membrane, and R is the bulk resistance of the electrolyte membrane. The resistance value was obtained at the intersection of the EIS curve and the real axis.

[0064] Cycle capacity maintenance measurement: The battery was cycled in a 25°C environment using a charge / discharge method of 2.5 to 4.3V. After 1000 cycles, the discharge capacity of the battery at this point was divided by the discharge capacity of the first cycle to determine the battery capacity maintenance rate at a charge / discharge rate of 1C / 1C. Please refer to Table 1 below for the measurement results.

[0065] [Table 1] Solid-state battery performance measurement results for Examples 1-22 and Comparative Examples 1-5

[0066] [Table 1] JPEG2026062488000002.jpg247160

[0067] From Examples 1 to 22 and Comparative Example 5 above, it can be seen that the present invention is a surface modification technology, that is, by modifying the surface of sulfide electrolytes and halide electrolytes with an electrolyte coating, the stability in air (even at high humidity) is significantly improved without greatly affecting conductivity. From Examples 1 to 22, it can be seen that by using the electrolyte coating provided by the present invention, the conductivity of sulfide electrolytes and halide electrolytes remains almost unchanged even after being placed at a dew point of -40°C for 24 hours, and the decrease in conductivity of sulfide electrolytes and halide electrolytes after being placed in an environment with 50% humidity (an environment with 50% humidity means adjusting the humidity conditions to 50% and the hygrometer showing 50%) for 24 hours is less than 20%. From Comparative Example 5, it can be seen that when no electrolyte coating is formed, the electrolyte film has poor water resistance and particularly poor conductivity retention.

[0068] Specifically, comparing Examples 1-8 with Comparative Examples 1-2, it can be seen that when the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) is within the range of 1-8:1, the electrolyte membrane can provide desirable water resistance, and both the conductivity retention rate and capacity of the solid-state battery are relatively high. That is, at a dew point of -40°C, the conductivity retention rate of the solid-state battery after 24 hours is greater than 50%, and the initial 1C capacity is greater than 180 mAh / g. Furthermore, when the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) is within the range of 2-6:1, both the water resistance of the electrolyte membrane and the conductivity retention rate and capacity of the solid-state battery are excellent, and the best performance is achieved when the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) is 4:1, the water contact angle can reach 137°, the conductivity retention rate can reach 90%, and the initial 1C capacity is 220 mAh / g. Comparative Example 1 shows that when the amount of perfluorohexylethyl methacrylate is excessively low (e.g., less than 1), the water resistance and conductivity retention of the corresponding electrolyte coating are very poor. Conversely, when the amount of perfluorohexylethyl methacrylate is excessively high (e.g., more than 8), the effect of the absolute value of conductivity becomes excessively large, resulting in a lower capacity.

[0069] Furthermore, from Example 2, it can be seen that when the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) is 1:1, the capacity of the solid-state battery is relatively high, with an initial capacity of 225 mAh / g at 1C. This is because, at this time, the amount of perfluorohexylethyl methacrylate (A) is relatively small and the amount of butyl methacrylate (B) is relatively large, resulting in a high capacity of the solid-state battery. Furthermore, from Example 8, it can be seen that when the molar ratio of perfluorohexylethyl methacrylate (A) to butyl methacrylate (B) is 8:1, the water resistance of the electrolyte coating is preferable, the water contact angle can reach 145°, and the conductivity retention rate is high, reaching 93%. This is because, at this time, the amount of perfluorohexylethyl methacrylate (A) is relatively large and the amount of butyl methacrylate (B) is relatively small, resulting in preferable water resistance and conductivity retention rate of the solid-state battery. In this invention, perfluorohexylethyl methacrylate (A) provides water resistance, and butyl methacrylate (B) has a low melting point, which is beneficial for processability. Therefore, the ratio of the two must be balanced, and it can be seen that the greater the amount of perfluorohexylethyl methacrylate (A), the greater the effect on conductivity.

[0070] Comparing Examples 9-16 with Comparative Examples 3-4, it can be seen that the electrolyte coating thickness is 20nm-100nm, and can be arbitrarily 50nm. This is because when the electrolyte coating thickness is within the range of 20nm-100nm, it does not affect the conductivity of the solid-state battery, and the conductivity retention rate and capacity of the solid-state battery are relatively high. Furthermore, when the electrolyte coating thickness is 50nm, the best performance can be achieved. Comparative Example 3 shows that if the electrolyte coating is excessively thin (e.g., less than 20nm), the hydrophobicity of the electrolyte coating is poor, which can reduce the conductivity retention rate of the solid-state battery. Conversely, Comparative Example 4 shows that if the electrolyte coating is excessively thick (e.g., thicker than 100nm), it has an excessively large impact on the absolute value of the conductivity of the solid-state battery, and the capacity decreases.

[0071] Also, from Example 9, it can be seen that when the electrolyte coating is thin (20 nm), the capacity of the solid battery is high (the initial capacity at 1C is 224 mAh / g). Also, from Example 16, it can be seen that when the electrolyte coating is thick (100 nm), the water resistance of the solid battery is favorable and the conductivity retention rate is also high. Therefore, it is necessary to achieve a favorable balance of the corresponding performance by selecting the thickness of the electrolyte coating. In the present invention, when the thickness of the electrolyte coating is 50 nm, each performance of the solid battery is relatively excellent.

[0072] From Examples 17 to 22, in the present invention, the sulfide electrolyte is Li 7-x PS 6-x Cl x (0 < x < 2), Li 7-x PS 6-x [[ID=X]]Br x (0 < x < 2) contains one or more of them, and it can be seen that the halide electrolyte contains one or more of Li3InCl6, Li3YCl6, and Li2ZrCl6. The present invention solves the problem that the above-mentioned sulfide electrolyte and halide electrolyte are unstable in air by means of a surface modification technique, and reduces the influence of moisture in the air on their electrochemical performance.

Industrial Applicability

[0073] In summary, by using the electrolyte coating provided by the present invention, the stability of the sulfide electrolyte and the halide electrolyte in air (even at high humidity) is significantly improved without significantly affecting their conductivities, and the conductivity retention rate and capacity of the solid battery are further increased.

[0074] The features of several embodiments have been outlined above so that those skilled in the art may better understand aspects of the present invention. Those skilled in the art will understand that, based on the present invention, other processes and structures can be easily designed or modified to achieve the same purposes and / or advantages as the embodiments described herein. Those skilled in the art will also understand that such equivalent structures will not depart from the spirit and scope of the present invention, and that many changes, substitutions, and modifications can be made herein without departing from the spirit and scope of the present invention.

Claims

1. Electrolyte coating, The electrolyte coating is applied to the surface of a solid electrolyte, and the solid electrolyte comprises one or both of a sulfide electrolyte and a halide electrolyte. The electrolyte coating is a copolymer of perfluorohexylethyl methacrylate and butyl methacrylate. Characterized by, Electrolyte coating.

2. The molar ratio of perfluorohexylethyl methacrylate to butyl methacrylate is 1 to 8:

1. Characterized by, The electrolyte coating according to claim 1.

3. The molar ratio of perfluorohexylethyl methacrylate to butyl methacrylate is 2 to 6:

1. Characterized by, The electrolyte coating according to claim 2.

4. The molar ratio of perfluorohexylethyl methacrylate to butyl methacrylate is 4:

1. Characterized by, The electrolyte coating according to claim 2.

5. The thickness of the electrolyte coating is 20 nm to 100 nm. Characterized by, The electrolyte coating according to claim 1.

6. The thickness of the electrolyte coating is 50 nm. Characterized by, The electrolyte coating according to claim 5.

7. The sulfide electrolyte is Li ７－ｘ PS ６－ｘ Cl ｘ (0<x<2), Li ７－ｘ PS ６－ｘ Br ｘ (Includes one or more of the following: 0 < x < 2) Characterized by, The electrolyte coating according to claim 1.

8. The halide electrolyte contains Li ３ InCl ６ , Li ３ YCl ６ , Li ２ ZrCl ６ and contains one or more of them. Characterized by, The electrolyte coating according to claim 1.

9. It comprises a positive electrode sheet, a negative electrode sheet, and a solid electrolyte. The surface of the solid electrolyte is coated with the electrolyte coating according to any one of claims 1 to 8. Characterized by, solid state battery.

10. Includes the solid battery described in claim 9 Characterized by, Power consuming equipment.

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