Composite material, its manufacturing method, and lithium battery

Abstract

This application discloses a composite material, a manufacturing method thereof, and a lithium battery for lithium batteries. The composite material includes a halide solid electrolyte and a coating layer coated on the halide solid electrolyte, the coating layer comprising a catecholamine self-polymer. The purpose of this application is to solve the problem of poor environmental stability of conventional halide solid electrolytes.

Description

[Technical Field]

[0001] This application claims priority based on a Chinese patent application bearing application number 202310474299.3, filed with the China Patent Office on April 25, 2023, and entitled "Composite material and manufacturing method thereof, solid electrolyte thin film and lithium battery," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to lithium batteries, and more particularly to a composite material, a method for manufacturing the same, and a lithium battery. [Background technology]

[0003] Solid electrolytes are a key component of solid-state batteries, and together with electrode materials, they determine the battery's energy density, cycle life, and safety performance. Inorganic solid electrolytes, with their inherent single-ion conductivity and high stability, offer advantages such as high thermal stability, flame and explosion resistance, high cycle stability, and strong impact resistance, making them a key direction for future electrolyte development. Inorganic solid electrolytes are primarily classified into three types: oxides, sulfides, and halides. Oxide inorganic solid electrolytes require high sintering temperatures during material synthesis and subsequent battery manufacturing processes to improve interfacial contact, which not only increases the susceptibility to interfacial reactions but also increases battery manufacturing costs. Sulfide solid electrolytes have limitations, such as poor environmental stability, poor compatibility with electrode materials such as oxide-based cathodes and lithium metal, poor interfacial contact at low pressures, and a narrow potential window. On the other hand, halide solid electrolytes are considered promising next-generation solid electrolyte materials due to their high lithium ion mobility, good mechanical flexibility, high electrochemical oxidation voltage, excellent compatibility with high-pressure oxide-based cathode materials, and simple synthesis.

[0004] However, halide solid electrolytes suffer from poor environmental stability, which has hindered further development and application of halide solid electrolytes. Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, the present application provides a composite material that can overcome the poor environmental stability of conventional halide solid electrolytes, a method for producing the same, and a lithium battery.

[0006] In a first aspect, the present application provides a composite material including a halide solid electrolyte and a coating layer coated on the halide solid electrolyte, wherein the material of the coating layer includes a catecholamine self-polymer.

[0007] Optionally, in some embodiments of the present application, the monomer of the catecholamine self-polymer contains catecholamine and its derivatives, and the catecholamine includes one or more of 3,4-dihydroxyphenylethylamine, (R)-4-(2-(methylamino)-1-hydroxyethyl]-1,2-benzenediol, and 1-(3,4-dihydroxyphenyl)-2-aminoethanol.

[0008] Optionally, in some embodiments of the present application, the coating layer has a thickness of 2 to 50 nm.

[0009] Optionally, in some embodiments of the present application, the halide solid electrolyte has the formula Li a MX b where M is at least one of a Group IIIB metal element or a Group IIIA metal element, X is at least one of F, Cl, Br or I, and 10≧a≧0, and 13≧b≧1.

[0010] Optionally, in some embodiments of the present application, the halide solid electrolyte may be at least one of Li3ScCl3Br3, Li3InCl6, or Li3YBr6.

[0011] In a second aspect, the present application provides a method for producing a composite material, the method comprising the steps of: mixing a halide solid electrolyte, a coating monomer, and a solvent; and causing the coating monomer to self-polymerize on a surface of the halide solid electrolyte to form a coating layer; Here, the present invention provides a method for producing a composite material, wherein the coating monomer contains catecholamine and its derivatives.

[0012] Optionally, in some embodiments of the present application, the mass ratio of the halide solid electrolyte to the coating monomer is 70:(1 to 8).

[0013] Optionally, in some embodiments of the present application, the self-polymerization reaction is carried out in an environment with a pH of 8.5 to 8.8.

[0014] Optionally, in some embodiments of the present application, the catecholamines include one or more of 3,4-dihydroxyphenylethylamine, (R)-4-(2-(methylamino)-1-hydroxyethyl]-1,2-benzenediol, 1-(3,4-dihydroxyphenyl)-2-aminoethanol, and / or The halide solid electrolyte has the chemical formula Li a MX b where M is at least one of a Group IIIB metal element or a Group IIIA metal element, X is at least one of F, Cl, Br or I, and 10≧a≧0, and 13≧b≧1.

[0015] Optionally, in some embodiments of the present application, the step of mixing a halide solid electrolyte, a coating monomer, and a solvent, and causing the coating monomer to self-polymerize on the surface of the halide solid electrolyte to form a coating layer to obtain a composite material, may include: dispersing the halide solid electrolyte in the solvent to obtain an electrolyte dispersion; mixing the electrolyte dispersion with a buffer solution having a pH of 7.5 to 8.5 to form a mixed system, and then adding an alkaline substance to adjust the pH of the mixed system to 8.5 to 8.8; The method includes a step of adding the coating monomer to the mixed system, and carrying out a reaction while controlling the pH of the mixed system to maintain it at 8.5 to 8.8, and then centrifuging and drying the reaction product to obtain a composite material.

[0016] Optionally, in some embodiments of the present application, in the step of dispersing a halide solid electrolyte in a solvent to obtain an electrolyte dispersion, the concentration of the halide solid electrolyte in the electrolyte dispersion is 0.2 to 1 g / ml.

[0017] Optionally, in some embodiments of the present application, the solvent comprises at least one of n-heptane, n-hexane, ethanol, methanol, isopropanol, ethylene glycol, or an ether.

[0018] Optionally, in some embodiments of the present application, the step of mixing the electrolyte dispersion with a buffer solution having a pH of 7.5 to 8.5 to form a mixed system, and then adding an alkaline substance to adjust the pH of the mixed system to 8.5 to 8.8, The buffer comprises at least one of Tris-HCl buffer, 4-hydroxyethylpiperazineethanesulfonic acid, N-tris(hydroxymethyl)methylglycine, phosphoric acid, citric acid, carbonic acid, acetic acid, or barbituric acid.

[0019] Optionally, in some embodiments of the present application, the mass ratio of the halide solid electrolyte to the buffer solution is 70:(1-4).

[0020] Optionally, in some embodiments of the present application, the alkaline substance comprises one or more inorganic bases or organic bases, wherein the inorganic base is one or more selected from the group consisting of alkali metal oxides, alkali metal hydroxides, alkali metal bicarbonates, alkali metal carbonates, alkaline earth metal oxides, alkaline earth metal hydroxides, and alkaline earth metal bicarbonates, and the organic base is one or more selected from the group consisting of alkali metal salts of organic acids, alkali metal salts of alcohols, amine compounds, and alkylammonium hydroxides.

[0021] Optionally, in some embodiments of the present application, the inorganic base is one or more selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, sodium oxide, potassium oxide, calcium oxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium bicarbonate, and barium hydroxide; the alkali metal salt of the organic acid includes one or more of sodium acetate and potassium acetate; the alkali metal salt of the alcohol includes one or more of sodium ethoxide and potassium ethoxide; the alkylamine compound includes one or more of ethylenediamine, octylamine, dioctylamine, trioctylamine, and oleylamine; and the alkylammonium hydroxide includes one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide.

[0022] Optionally, in some embodiments of the present application, the step of adding the coating monomer to the mixed system, and then carrying out a reaction while controlling the pH of the mixed system to be 8.5 to 8.8, and then centrifuging and drying the reaction product to obtain a composite material includes: The reaction is carried out at a temperature of 20 to 80°C, and / or The reaction is carried out for 0.5 to 24 hours.

[0023] Optionally, in some embodiments of the present application, the reaction product is centrifuged at a rotation speed of 2000 to 15000 r / min for 2 to 5 minutes.

[0024] Optionally, in some embodiments of the present application, the step of mixing a halide solid electrolyte, a coating monomer, and a solvent, and causing the coating monomer to self-polymerize on the surface of the halide solid electrolyte to form a coating layer to obtain a composite material, is performed in an inert atmosphere containing one or more of nitrogen gas, helium gas, and argon gas.

[0025] In a third aspect, the present application provides a lithium battery comprising a positive electrode, a thin solid electrolyte film, and a negative electrode, wherein a material of the thin solid electrolyte film comprises a composite material, wherein the composite material comprises the composite material described above, or wherein the composite material is manufactured by the manufacturing method described above.

[0026] According to the technical solution described in this application, by coating the surface of a halide electrolyte with a layer of catecholamine self-polymer, not only can the structural properties of the halide solid electrolyte be unaffected, but also the catecholamine self-polymer can function as an air barrier, thereby effectively improving the environmental stability of the material. In addition, because the catecholamine self-polymer has good flexibility, its use as a coating layer improves the surface flexibility of the halide electrolyte, improves the contact between the composite solid electrolyte thin film and the active particles, improves the interfacial contact stability between the solid electrolyte and the metal electrode, and improves the electrochemical stability of the battery. [Brief explanation of the drawings]

[0027] In order to more clearly describe the technical solutions in the embodiments of the present application, the following will briefly describe the drawings that need to be used in the description of the embodiments. The drawings in the following description are only a part of the present application, and it is obvious that those skilled in the art can derive other drawings based on these drawings without any creative work.

[0028] [Figure 1] 1 is a TEM image of a composite material according to an example of the present application. [Figure 2] 1 is a schematic flowchart of a method for manufacturing a solid electrolyte thin film according to an embodiment of the present application. [Figure 3] 1 shows an impedance spectrum of the conductivity of the solid electrolyte thin film produced in Example 1. [Figure 4] 2 shows the second cycle charge-discharge curve of the lithium battery prepared in Example 1. [Figure 5] 2 shows the second cycle charge-discharge curve of the lithium battery prepared in Comparative Example 1. [Figure 6]1 is a schematic flowchart of a method for manufacturing a solid electrolyte thin film according to another embodiment of the present application. [Figure 7] 1 is a schematic diagram illustrating the configuration of a lithium battery according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, the technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the present application, and are not all of the embodiments. All other embodiments that a person skilled in the art can obtain based on the embodiments of the present application without any creative work fall within the scope of protection of the present application. It should also be understood that the specific embodiments described herein are merely for the purpose of explaining and interpreting the present application, and do not limit the present application.

[0030] In this application, unless otherwise specified, directional terms used, such as "upper" and "lower," are specifically referring to the drawing directions in the drawings. Also, in the description of this specification, the term "including" means "including but not limited to."

[0031] Various embodiments of the present application may be presented in range form. The description of a range is merely for convenience and brevity and should not be construed as strictly limiting the scope of the present application. Thus, the description of a range should be considered to specifically disclose all possible subranges and individual numerical values ​​within that range. For example, description of a range of 1 to 6 specifically discloses subranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., and should also be considered to disclose single numbers within that range, such as 1, 2, 3, 4, 5, and 6, which are applicable to any range. Furthermore, when describing a numerical range herein, it includes any recited number (fractional or integer) within the stated range.

[0032] In this application, "and / or" describes a relationship between related objects and indicates that a three-way relationship may exist, for example, A and / or B may indicate that A exists alone, A and B exist simultaneously, or B exists alone, where A and B may be singular or plural.

[0033] As used herein, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these terms, including any combination of single terms or multiple terms. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can refer to a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, where a, b, and c can each be single or multiple.

[0034] The technical solution of the present application is implemented as follows:

[0035] In a first aspect, the present application provides a composite material. Referring to Figure 1, the composite material includes a halide solid electrolyte and a coating layer coated on the halide solid electrolyte, and the coating layer is made of a material including a catecholamine self-polymer.

[0036] According to the technical solution described in this application, by coating the surface of a halide electrolyte with a catecholamine self-polymer layer, it can function as an air barrier and effectively improve the environmental stability of the material. In addition, because the catecholamine self-polymer has excellent flexibility, when used as a coating layer, it can increase the surface flexibility of the halide electrolyte. The solid electrolyte thin film using the composite material has improved contact with the active particles, which improves the interfacial contact stability between the solid electrolyte and the metal electrode and the electrochemical stability of the battery.

[0037] The catecholamine self-polymer refers to a self-polymerization product formed by oxidation of a catecholamine compound. The catecholamine self-polymer has strong adhesion and can adhere well to the surface of a halide solid electrolyte to form a coating layer. The coating layer may partially or completely surround the halide solid electrolyte, but this is not limited thereto. In some preferred embodiments, the coating layer completely encapsulates the halide solid electrolyte, thereby further improving the environmental stability and compatibility with lithium metal of the material.

[0038] The catecholamines are amine compounds with an ortho-dihydroxybenzene (i.e., catechol) structure, which have a dihydroxybenzene nucleus (two hydroxy groups in the ortho position) and an amino group-containing side chain on the benzene nucleus. The catecholamines and their derivatives can undergo oxidation and self-polymerization under mild, weakly basic, wet conditions to produce catecholamine self-polymers with very strong adhesive properties. In some embodiments, the monomer of the catecholamine self-polymerization includes one or more of 3,4-dihydroxyphenylethylamine (CAS: 51-61-6) and its derivatives, (R)-4-(2-(methylamino)-1-hydroxyethyl]-1,2-benzenediol (CAS: 51-43-4) and its derivatives, and 1-(3,4-dihydroxyphenyl)-2-aminoethanol (CAS: 51-41-2) and its derivatives. The self-polymerization reaction of these materials is easy to control, produces few by-products, and the resulting coating layer has excellent adhesion and barrier properties without affecting the properties of the halide solid electrolyte itself.

[0039] The halide solid electrolyte has the chemical formula Li a MX b where M is at least one of a Group IIIB metal element and a Group IIIA metal element, X is at least one of F, Cl, Br and I, and 10≧a≧0, 13≧b≧1. For example, examples of halide solid electrolytes include Li3ScCl3Br3, Li3InCl6, and Li3YBr6.

[0040] In some embodiments, the coating layer has a thickness of 2 to 50 nm.

[0041] In a second aspect, the present application provides a method for producing the composite material, which includes a step S100 of mixing a halide solid electrolyte, a coating monomer, and a solvent, and then self-polymerizing the coating monomer on a surface of the halide solid electrolyte to form the coating layer, thereby obtaining the composite material, with reference to FIG. Here, the coating monomer includes catecholamine and its derivatives.

[0042] In some embodiments of the present application, the mass ratio of the halide solid electrolyte to the coating monomer is 70:(1 to 8), such as 70:1, 70:2, 70:3, 70:4, 70:5, 70:6, 70:7, 70:8, or a value between any two of the above values. Within these ranges, the coating layer formed by polymerization of the coating monomer can sufficiently cover the halide solid electrolyte and have a consistent thickness, which can improve the environmental stability of the material and its compatibility with lithium metal, and ensure the optimized effect of the material.

[0043] In some embodiments, the self-polymerization reaction of the coating monomer is carried out in an environment with a pH of 8.5 to 8.8. This pH environment can promote the reaction of the coating monomer to form a coating layer and improve the barrier effect of the coating layer. The pH of the acid-base environment can be 8.5, 8.6, 8.7, 8.8, or a value between any two of the above values.

[0044] In some embodiments, the coating monomer includes one or more of 3,4-dihydroxyphenylethylamine (CAS: 51-61-6) and its derivatives, (R)-4-(2-(methylamino)-1-hydroxyethyl]-1,2-benzenediol (CAS: 51-43-4) and its derivatives, and 1-(3,4-dihydroxyphenyl)-2-aminoethanol (CAS: 51-41-2) and its derivatives.

[0045] In some embodiments, the halide solid electrolyte has the formula Li a MX b where M is at least one of a Group IIIB metal element and a Group IIIA metal element, X is at least one of F, Cl, Br and I, and 10≧a≧0, 13≧b≧1. Examples of the halide solid electrolyte include Li3ScCl3Br3, Li3InCl6, and Li3YBr6.

[0046] Referring to FIG. 6, in some embodiments, step S100 may be performed as follows. S10: dispersing a halide solid electrolyte in a solvent to obtain an electrolyte dispersion; S20: mixing the electrolyte dispersion with a buffer solution having a pH of 7.5 to 8.5 to form a mixed system, and then adding an alkaline substance to adjust the pH of the mixed system to 8.5 to 8.8; A coating monomer is added to the mixture, and a reaction is carried out while controlling the pH of the mixture to be maintained at 8.5 to 8.8. Then, the reaction product is centrifuged and dried to obtain a composite material (S30).

[0047] In some embodiments, in step S10, the solvent may be an alcohol, alkane, or ether having good solubility, for example, at least one of n-heptane, n-hexane, ethanol, methanol, isopropanol, ethylene glycol, and dimethyl ether, but is not limited thereto.

[0048] In some embodiments, the concentration of the halide solid electrolyte is 0.2 to 1 g / ml, for example, 0.2 mg / ml, 0.3 mg / ml, 0.4 mg / ml, 0.5 mg / ml, 0.6 mg / ml, 0.7 mg / ml, 0.8 mg / ml, 0.9 mg / ml, 1 mg / ml, or a value between any two of the above values. By selecting an electrolyte dispersion with a concentration within this range, it is possible to ensure the uniformity of the dispersion and prevent aggregation, while also ensuring a sufficient concentration distribution when mixed with the coating monomer, ensuring sufficient contact between the two, and allowing the self-polymerization product of the coating monomer to uniformly coat the surface of the halide solid electrolyte.

[0049] In some embodiments, to promote sufficient dispersion of the halide solid electrolyte, after mixing with the solvent, the halide solid electrolyte is dispersed by ultrasonic waves to obtain a uniform dispersion. Here, the ultrasonic conditions may be a frequency of 30 to 50 kHz and a time of 0.05 to 2 hours, and within these condition ranges, the halide solid electrolyte can be uniformly dispersed in the solvent.

[0050] In step S20, a buffer solution is added to create a stable acid-base environment with a pH close to 8.5-8.8. In some embodiments, a buffer solution with a pH of 7.5-8.5 is added. Specifically, the buffer solution may include, but is not limited to, at least one of Tris-HCl buffer, 4-hydroxyethylpiperazineethanesulfonic acid, N-tris(hydroxymethyl)methylglycine, phosphate, citric acid, carbonate, acetate, and barbiturate buffer.

[0051] In some embodiments, to achieve a pH of 8.5 to 8.8 in the reaction system, it is necessary to add a pH adjuster to the mixture to adjust the pH. In this embodiment, the pH adjuster is an alkaline substance. The alkaline substance includes one or more inorganic bases or organic bases, where the inorganic base is one or more selected from the group consisting of alkali metal oxides, alkali metal hydroxides, alkali metal bicarbonates, alkali metal carbonates, alkaline earth metal oxides, alkaline earth metal hydroxides, and alkaline earth metal bicarbonates, and the organic base is one or more selected from the group consisting of alkali metal salts of organic acids, alkali metal salts of alcohols, amine compounds, and alkylammonium hydroxides. The inorganic base is one or more selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, sodium oxide, potassium oxide, calcium oxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium bicarbonate, and barium hydroxide; the alkali metal salt of an organic acid includes one or more of sodium acetate and potassium acetate; the alkali metal salt of an alcohol includes one or more of sodium ethoxide and potassium ethoxide; the alkylamine compound includes one or more of ethylenediamine, octylamine, dioctylamine, trioctylamine, and oleylamine; and the alkylammonium hydroxide includes one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide.

[0052] In a specific implementation, the alkaline substance can be added as a solution. For example, an alkaline solution can be prepared by dissolving the alkaline substance in a solvent. This allows the alkaline substance to be rapidly dispersed throughout the mixed system, preventing localized, rapid pH fluctuations and deviations from the target pH value when the mixed system is adjusted. Specifically, the solvent may be an alcohol with good solubility, such as, but not limited to, at least one of ethanol, methanol, and ethylene glycol. The concentration of the alkaline substance in the alkaline solution may be 0.2 to 1 mol / L. Furthermore, to promote uniform dispersion of the alkaline substance, the alkaline substance may be ultrasonically dispersed. Here, the ultrasonic conditions may be a frequency of 30 to 50 kHz and a duration of 5 to 20 minutes.

[0053] In some embodiments, the mass ratio of the halide solid electrolyte to the buffer solution is 70:(1-4), and may be, for example, 70:1, 70:2, 70:3, 70:4, or a value between any two of the above values.

[0054] In step S30, the reaction temperature is 20°C to 80°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 65°C, 70°C, 80°C, or a value between any two of the above values. Within these ranges, the reaction can be promoted to proceed rapidly. Preferably, the reaction temperature is 60°C.

[0055] In some embodiments of the present application, the reaction time is 0.5 to 24 hours, for example, 0.5, 1, 2, 4, 6, 7, 8, 9, 10, 11, 12, 16, 18, 20, 22, 24 hours, or a value between any two of the above values. Within these ranges, coating uniformity and reaction degree can be well controlled.

[0056] In some embodiments, the coating monomer may be added as a solution. For example, dissolving the coating monomer in a solvent to prepare a monomer solution allows the monomer solution to be rapidly dispersed in the mixed system, thereby preventing local excess of the coating monomer and its effect on the coating. Specifically, the solvent may be an alcohol with good solubility. Examples of the solvent include, but are not limited to, at least one of ethanol, methanol, and ethylene glycol. The concentration of the coating monomer in the monomer solution may be 0.04 to 0.16 mol / L, such as 0.04 mol / L, 0.05 mol / L, 0.07 mol / L, 0.09 mol / L, 0.1 mol / L, 0.11 mol / L, 0.13 mol / L, 0.14 mol / L, 0.16 mol / L, or a value between any two of the above. To promote uniform dispersion of the coating monomer, an ultrasonic dispersion method may be used, in which ultrasonic dispersion is performed at a frequency of 30 kHz to 50 kHz for 5 to 20 minutes.

[0057] In some embodiments, the step of "adding the coating monomer to the mixed system and controlling the pH of the mixed system to maintain 8.5 to 8.8 to carry out the reaction" is performed under stirring. Stirring promotes uniform dispersion of the coating monomer in the mixed system and ensures uniform coating of the exterior of the electrolyte. The rotation speed of the stirrer may be 400 to 1200 r / min.

[0058] In some embodiments, the centrifugation is performed at a rotation speed of 2000 to 15000 r / min for 2 to 5 minutes, thereby enabling the composite material to be separated well and improving the yield.

[0059] In some embodiments, the centrifuged solid is dried by vacuum drying at a temperature between 60 and 100°C, such as 60°C, 70°C, 80°C, 90°C, 100°C, etc. This allows for good control of the drying effect.

[0060] In some embodiments, each step (S100 or S10 to S30) of the present manufacturing method is performed in an inert atmosphere containing nitrogen, helium, argon, etc. Specific implementation may be performed in a glove box to avoid the influence of water, oxygen, etc.

[0061] In a third aspect, the present application provides a solid electrolyte thin film 20, wherein a material of the solid electrolyte thin film 20 includes a composite material, and the composite material includes the composite material described above or is manufactured by the manufacturing method described above.

[0062] The method for producing the solid electrolyte thin film 20 includes placing the composite material on the surface of a substrate and cold-pressing or hot-pressing it to form a sheet to obtain the solid electrolyte thin film 20. Here, the conditions for forming the solid electrolyte thin film 20 by pressing or hot-pressing the composite material are a pressure of 200 to 600 MPa and a time of 2 to 6 minutes.

[0063] The solid electrolyte thin film 20 according to the present invention has a strong and dense coating layer on its surface. The coating layer not only does not affect the halide solid electrolyte but also serves to block air, thereby effectively improving the environmental stability of the thin film. Furthermore, catecholamine self-polymers have good flexibility, and forming a coating layer improves the surface flexibility of the halide electrolyte. This improves the contact between the solid electrolyte thin film 20 and the active particles, improving the interfacial contact stability between the solid electrolyte and the metal electrode, and improving the electrochemical stability of the battery.

[0064] In a fourth aspect, the present application also provides a lithium battery 100. Referring to FIG. 7, the lithium battery 100 includes a positive electrode 10, a thin solid electrolyte film 20 including the above-described thin solid electrolyte film 20, and a negative electrode 30.

[0065] The solid electrolyte thin film 20 according to the present application can be used in the lithium battery 100 by replacing the PP separator in the lithium battery 100, and by simply combining the solid electrolyte thin film 20 with the positive electrode 10 and the negative electrode 30, a lithium battery 100 with stable performance and a long life can be formed.

[0066] The assembly process for the all-solid-state lithium metal battery 100 involves using a mechanical clamp as a carrier for solid-state battery assembly and testing. First, a cut sheet of cathode 10 is placed at the bottom inside the clamp. Then, a composite material is placed on the surface of the cathode 10 sheet and cold-pressed to form a sheet to obtain a cathode-solid electrolyte thin film sheet. Lithium metal is then placed on the surface of the cathode-solid electrolyte thin film sheet and sealed by cold pressing under pressure to obtain the all-solid-state lithium metal battery 100. Here, the conditions for cold-pressing the composite material to form the solid electrolyte thin film 20 are a pressure of 200 to 600 MPa and a time of 2 to 6 minutes. The conditions for sealing by cold pressing are a pressure of 30 to 200 MPa and a time of 0.5 to 2 hours.

[0067] It is understood that the above assembly process is carried out under an inert atmosphere, which may include, but is not limited to, nitrogen, helium, argon, etc. In particular, the process may be carried out in a glove box to avoid the influence of water, oxygen, etc.

[0068] The technical solutions and effects of the present application will be described in detail using specific examples and comparative examples. The following examples are only a part of the present application and are not intended to specifically limit the present application.

[0069] Example 1 (1) Manufacturing of composite materials (1) Lithium hydroxide was dispersed in ethanol and ultrasonicated at 50 kHz for 20 minutes to obtain a lithium hydroxide solution with a concentration of 0.5 mol / L. 3,4-dihydroxyphenylethylamine, a coated monomer, was dispersed in ethanol and ultrasonicated at 50 kHz for 20 minutes to obtain a 3,4-dihydroxyphenylethylamine monomer solution with a concentration of 0.08 mol / L. (2) The halide solid electrolyte Li3InCl6 was dispersed in an ethanol solvent using ultrasonic waves to obtain a uniform electrolyte dispersion with a dispersion concentration of 0.3 g / ml. The ultrasonic conditions for dispersion were a frequency of 40 kHz and a duration of 0.5 hours. (3) The Tris-HCl buffer solution was mixed with the electrolyte dispersion obtained in step (2) and thoroughly stirred until homogeneous. The pH of the mixture was then adjusted to approximately 8.5 using the lithium hydroxide solution from step (1) while continuously stirring at a rotation speed of 1200 r / min, yielding mixed solution a. Next, the monomer solution from step (1) was slowly added to mixed solution a while continuously stirring at a rotation speed of 1200 r / min. After that, the mixture was stirred for an additional 0.5 and 1 h, respectively, and the pH was measured twice to ensure that the pH of the mixture reached approximately 8.5 (if the pH was not between 8.5 and 8.8, additional lithium hydroxide solution was added dropwise). Mixed solution b was obtained. The halide solid electrolyte, coated monomer, and Tris-HCl buffer solution were added in a mass ratio of 70:4:2. (4) Mixture B was heated to 60°C while stirring at 1200 r / min. After reacting at this temperature for 8 hours, it was cooled to room temperature and suction filtered to obtain the crude coated product. The crude coated product was washed 2-3 times with ethanol and centrifuged at 8000 r / min for 5 minutes. The precipitate was removed and vacuum dried at 80°C for 24 hours to obtain a composite material: a polydopamine-modified Li3InCl6 halide solid electrolyte (PDA@Li3InCl6). The above steps (1) to (4) were carried out in a glove box under an argon gas environment. The composite material was scanned with a transmission electron microscope, and the results are shown in Figure 1. It can be seen that the surface of the halide solid electrolyte in the composite material is covered with a coating layer about 3 nm thick.

[0070] (2) Manufacturing of positive electrode sheets The positive electrode active material is lithium nickel cobalt manganese oxide (LiNi) 0.8 Co 0.1 Mn 0.138.6 g of O2 (NCM811), 0.48 g of Super Pll conductive carbon black, 0.24 g of conductive graphite KS-6, 10.4 g of 5% polyvinylidene fluoride adhesive, and n-methylpyrrolidone solvent were weighed and mixed by ball milling to obtain a positive electrode slurry. The positive electrode slurry was applied and initially dried, then transferred to a vacuum oven for further vacuum drying, rolled, and cut to obtain a positive electrode sheet. The mass ratio of the positive electrode active materials NCM811, conductive carbon black Super Pll, conductive graphite KS-6, and polyvinylidene fluoride (PVDF) adhesive was 96.9:1.2:0.6:1.3. The ball milling conditions were a speed of 300 r / min and a time of 3 hours. The vacuum drying conditions were a vacuum of 133 Pa or less, a temperature of 100°C, and a time of 24 hours.

[0071] (3) Assembly of all-solid-state lithium metal batteries The mechanical clamp was used as a carrier for assembling and testing solid-state batteries. First, the nickel-cobalt manganese oxide (NCM811) cathode sheet cut in step (2) was placed on the bottom layer inside the clamp. Then, the composite material (PDA@Li3InCl6) obtained in step (1) was placed on the surface of the cathode sheet and cold-pressed to form a sheet, resulting in a cathode-solid electrolyte thin film sheet (NCM811-PDA@Li3InCl6). Lithium metal was then placed on the surface of the cathode-solid electrolyte thin film sheet (NCM811-PDA@Li3InCl6) and sealed by cold pressing under pressure to form an all-solid-state lithium metal battery with a surface-coated halide solid electrolyte (NCM811 / PDA@Li3InCl6). 6 / Li) was obtained. Here, the inner diameter of the mechanical clamp was Φ 20 mm, the diameter of the positive electrode sheet was Φ 16 mm, and the diameter of the lithium metal was Φ 18 mm. The conditions for cold pressing the halide solid electrolyte into the sheet were a pressure of 300 MPa and a time of 4 minutes, and the conditions for sealing by cold pressing were a pressure of 80 MPa and a time of 1 hour. The battery assembly process (3) above was carried out in a glove box under an argon gas environment.

[0072] Example 2 This embodiment is basically the same as the first embodiment, except that steps (1) to (4) of this embodiment are changed as follows. (1) Lithium hydroxide was dispersed in ethanol and ultrasonicated at a frequency of 50 kHz for 20 minutes to obtain a lithium hydroxide solution with a concentration of 0.5 mol / L. 3,4-Dihydroxyphenylethylamine, a coating monomer, was dispersed in ethanol and ultrasonicated at a frequency of 50 kHz for 20 minutes to obtain a monomer solution with a concentration of 0.08 mol / L of 3,4-Dihydroxyphenylethylamine. (2) A halide solid electrolyte, Li3InCl6, was dispersed in an ethanol solvent using ultrasonic waves to obtain a uniform electrolyte dispersion with a dispersion concentration of 0.2 g / ml. The ultrasonic conditions for dispersion were a frequency of 40 kHz and a duration of 0.5 hours. (3) The Tris-HCl buffer solution was mixed with the electrolyte dispersion obtained in step (2) and thoroughly stirred until homogeneous. The pH of the mixture was then adjusted to approximately 8.7 using the lithium hydroxide solution from step (1) while continuously stirring at a rotation speed of 600 r / min, yielding mixed solution a. Next, the monomer solution from step (1) was slowly added to mixed solution a while continuously stirring at a rotation speed of 600 r / min. After further stirring for 0.5 and 1 h, the pH was measured twice to ensure that the pH of the mixture reached approximately 8.7 (if the pH was not between 8.5 and 8.8, additional lithium hydroxide solution was added dropwise). Mixed solution b was obtained. The halide solid electrolyte, coated monomer, and Tris-HCl buffer solution were added in a mass ratio of 70:4:2. (4) Mixture B was heated to 60°C while stirring at 600 r / min. After reacting at this temperature for 0.5 h, it was cooled to room temperature and suction filtered to obtain the crude coated product. The crude coated product was washed two to three times with ethanol and centrifuged at 3000 r / min for 5 minutes. The precipitate was removed and vacuum dried at 80°C for 24 hours to obtain a composite material: a polydopamine-modified Li3InCl6 halide solid electrolyte (PDA@Li3InCl6). The other steps and parameters remain unchanged.

[0073] Example 3 This embodiment is basically the same as the first embodiment, except that steps (1) to (4) of this embodiment are changed as follows. (1) Lithium hydroxide was dispersed in isopropanol and ultrasonicated at a frequency of 50 kHz for 20 minutes to obtain a lithium hydroxide solution with a concentration of 0.5 mol / L. 3,4-Dihydroxyphenylethylamine, a coating monomer, was dispersed in isopropanol and ultrasonicated at a frequency of 50 kHz for 20 minutes to obtain a monomer solution with a concentration of 0.08 mol / L of 3,4-Dihydroxyphenylethylamine. (1) A halide solid electrolyte, Li3InCl6, was dispersed in isopropanol using ultrasonic waves to obtain a uniform electrolyte dispersion with a dispersion concentration of 1 g / ml. The ultrasonic conditions for dispersion were a frequency of 40 kHz and a duration of 0.5 hours. (1) Tris-HCl buffer solution was mixed with the electrolyte dispersion obtained in step (2) and thoroughly stirred until homogeneous. Then, using the lithium hydroxide solution from step (1), the pH of the mixture was adjusted to approximately 8.5 while continuously stirring at a rotation speed of 1200 r / min to obtain mixed solution a. Next, the monomer solution from step (1) was slowly added to mixed solution a while continuously stirring at a rotation speed of 1200 r / min. After that, the mixture was stirred for an additional 0.5 and 1 h, respectively, and then the pH was measured twice to ensure that the pH of the mixture reached approximately 8.5 (if the pH was not between 8.5 and 8.8, additional lithium hydroxide solution was added dropwise). Mixed solution b was obtained. The halide solid electrolyte, the coated monomer, and the Tris-HCl buffer solution were added in a mass ratio of 70:4:2. (1) Mixture B was heated to 60°C while stirring at 1200 r / min. After reacting at this temperature for 24 hours, it was cooled to room temperature and filtered under suction to obtain the crude coated product. The crude coated product was washed two to three times with ethanol and centrifuged at 2000 r / min for 3 minutes. The precipitate was removed and dried under vacuum at 80°C for 24 hours to obtain a composite material: a polydopamine-modified Li3InCl6 halide solid electrolyte (PDA@Li3InCl6). The other steps and parameters remain unchanged.

[0074] Example 4 This embodiment is basically the same as the first embodiment, except that steps (1) to (4) of this embodiment are changed as follows. (1) Lithium hydroxide was dispersed in ethanol and ultrasonicated at 50 kHz for 20 minutes to obtain a lithium hydroxide solution with a concentration of 0.5 mol / L. The coating monomer, 1-(3,4-dihydroxyphenyl)-2-aminoethanol, was dispersed in ethanol and ultrasonicated at 50 kHz for 20 minutes to obtain a monomer solution with a concentration of 0.08 mol / L of 1-(3,4-dihydroxyphenyl)-2-aminoethanol. (2) A halide solid electrolyte, Li3InCl6, was dispersed in an ethanol solvent using ultrasonic waves to obtain a uniform electrolyte dispersion with a dispersion concentration of 0.3 g / ml. The ultrasonic conditions for dispersion were a frequency of 40 kHz and a duration of 0.5 hours. (3) The Tris-HCl buffer solution was mixed with the electrolyte dispersion obtained in step (2) and thoroughly stirred until homogeneous. Then, using the lithium hydroxide solution from step (1), the pH of the mixture was adjusted to approximately 8.8 while continuously stirring at a rotation speed of 1200 r / min, to obtain mixed solution a. Next, the monomer solution from step (1) was slowly added to mixed solution a while continuously stirring at a rotation speed of 1200 r / min. After that, the mixture was stirred for an additional 0.5 and 1 h, respectively, and then the pH was measured twice to ensure that the pH of the mixture reached approximately 8.8 (if the pH was not 8.5-8.8, additional lithium hydroxide solution was added dropwise). Mixed solution b was obtained. The halide solid electrolyte, the coated monomer, and the Tris-HCl buffer solution were added in a mass ratio of 70:4:2. (4) Mixture B was heated to 60°C while stirring at 1200 r / min. After reacting at this temperature for 8 hours, it was cooled to room temperature and filtered under suction to obtain the crude coated product. The crude coated product was washed two to three times with ethanol and centrifuged at 15000 r / min for 2 minutes. The precipitate was removed and dried in vacuum at 80°C for 24 hours to obtain a composite material: a poly(1-(3,4-dihydroxyphenyl)-2-aminoethanol)-modified Li3InCl6 halide solid electrolyte. The other steps and parameters remain unchanged.

[0075] Example 5 This example is essentially the same as Example 1, except that in step (1) of this example, 3,4-dihydroxyphenylethylamine is replaced with (R)-4-(2-(methylamino)-1-hydroxyethyl]-1,2-benzenediol; the other parameters and steps remain unchanged.

[0076] Example 6 This embodiment is basically the same as Example 1, except that the supply mass ratio is changed from 70:4:2 to 70:2:1 in step (3) of this embodiment; other parameters and steps remain unchanged.

[0077] Example 7 This embodiment is basically the same as Example 1, except that the supply mass ratio is changed from 70:4:2 to 70:8:4 in step (3) of this embodiment; other parameters and steps remain unchanged.

[0078] Example 8 This embodiment is basically the same as Example 1, except that the supply mass ratio is changed from 70:4:2 to 70:10:5 in step (3) of this embodiment; other parameters and steps remain unchanged.

[0079] Example 9 This example is basically the same as Example 1, except that the heating temperature in step (4) of this example is changed from 60° C. to 20° C., and other parameters and steps remain unchanged.

[0080] Example 10 This embodiment is basically the same as embodiment 1, except that the heating temperature in step (4) of this embodiment is changed from 60° C. to 80° C., and other parameters and steps remain unchanged.

[0081] Example 11 This embodiment is basically the same as Example 1, except that in step (4) of this embodiment, the heating temperature is changed from 60°C to 85°C; other parameters and steps remain unchanged.

[0082] Example 12 This example is basically the same as Example 1, except that in step (2) of this example, the halide solid electrolyte is changed from Li3InCl6 to Li3YBr6, and the other parameters and steps are unchanged.

[0083] Comparative Example 1 This comparative example is basically the same as Example 1, except that in step (3) of this comparative example, a solid electrolyte thin film is produced by using a halide solid electrolyte that is not coated with a catecholamine self-polymer, i.e., the composite material is changed to Li3InCl6, and steps (1) to (4) are accordingly omitted.

[0084] Comparative Example 2 This comparative example is basically the same as Example 12, except that in step (3) of this comparative example, a solid electrolyte thin film was produced by using a halide solid electrolyte that was not coated with a catecholamine self-polymer, i.e., the composite material was changed to Li3YBr6, and steps (1) to (4) were accordingly omitted.

[0085] The solid electrolyte thin films and lithium batteries obtained in Examples 1 to 12 and Comparative Examples 1 and 2 were subjected to performance tests using the following detection method. (1) A charge-discharge cycle test was performed on a lithium battery using a charge-discharge cycle device and a constant current cut-off voltage charge-discharge method, and the charge-discharge curve was plotted. (2) The cut Au sheet was placed on the bottom layer inside the clamp, and then the composite material obtained in the example or the halide solid electrolyte not coated with catecholamine self-polymer obtained in the comparative example was placed on the surface of the Au and cold-pressed to obtain a gold-electrolyte sheet. Then, Au was placed on the surface of the gold-electrolyte sheet and sealed by cold pressing under pressure to obtain a gold / solid electrolyte thin film / gold. Here, the inner diameter of the mechanical clamp was 20 mm, the diameter of the cathode sheet was 16 mm, and the diameter of the lithium metal was 18 mm. The conditions for cold-pressing the halide solid electrolyte onto the sheet were 300 MPa and 4 minutes, and the conditions for cold-pressing were 80 MPa and 1 hour. The gold / solid electrolyte thin film / gold electrodes were connected to the working and auxiliary electrodes of an electrochemical workstation, respectively, and electrochemical impedance spectroscopy (EIS) tests were performed. The results are shown in Figures 4 and 5 and Table 1. In Figures 4 and 5, the horizontal axis represents specific capacity in mAh / g, and the vertical axis represents voltage in Vvs, Li + / Li.

[0086] [Table 1]

[0087] 4 and 5, the charge / discharge curves of Example 1 show a lower charge / discharge polarization voltage and a higher charge / discharge capacity than those of the comparative example, indicating that the coated halide electrolyte has a positive effect on ion transport in the porous electrode and on interfacial contact between the electrolyte and the electrode. This indicates that the solid electrolyte thin film according to the present invention, when coated with a catecholamine self-polymer coating layer, significantly improves environmental stability and compatibility with lithium metal, thereby improving the reversible capacity and charge / discharge cycle performance of the battery.

[0088] Table 1 and Figure 3 show that each Example has higher air stability than the Comparative Example. This indicates that the environmental stability of the solid electrolyte thin film according to the present invention is significantly improved by coating it with a catecholamine self-polymer coating layer. Furthermore, as can be seen from a comparison of the initial AC impedance values ​​of lithium / solid electrolyte / lithium at room temperature between each Example and Comparative Example in Table 1, coating the solid electrolyte thin film with a catecholamine self-polymer coating layer significantly reduces the interfacial impedance between the halide electrolyte and lithium metal. This indicates that the coating layer improves compatibility with lithium metal, thereby improving the reversible capacity and charge / discharge cycle performance of the battery.

[0089] The composite material, its manufacturing method, and lithium battery according to the examples of the present application are described in detail above. Although the principles and embodiments of the present application are described using specific examples in this specification, the description of the above examples is merely intended to aid in understanding the method and concept of the present application. Furthermore, those skilled in the art should understand that there may be changes in the specific embodiments and application scope based on the concept of the present application, and as such, the contents of this specification should not be construed as limiting the present application. [Explanation of symbols]

[0090] 100 lithium batteries, 10 cathodes, 20 thin solid electrolyte films, 30 anodes.

Claims

1. a halide solid electrolyte and a coating layer coated on the outside of the halide solid electrolyte, wherein the material of the coating layer includes a catecholamine self-polymer; Composite material.

2. The monomer of the catecholamine self-polymer contains catecholamine and a derivative thereof, and the catecholamine includes one or more of 3,4-dihydroxyphenylethylamine, (R)-4-(2-(methylamino)-1-hydroxyethyl]-1,2-benzenediol, and 1-(3,4-dihydroxyphenyl)-2-aminoethanol; The composite material of claim 1.

3. The thickness of the coating layer is 2 nm to 50 nm.

3. The composite material according to claim 1 or 2.

4. The halide solid electrolyte has the chemical formula Li ａ MX ｂ wherein M is at least one of a Group IIIB metal element or a Group IIIA metal element, X is at least one of F, Cl, Br or I, and 10≧a≧0 and 13≧b≧1; The composite material according to any one of claims 1 to 3.

5. The halide solid electrolyte is Li ３ ScCl ３ Br ３ , Li ３ InCl ６ , or Li ３ YBr ６ At least one of The composite material according to any one of claims 1 to 4.

6. 1. A method for producing a composite material, comprising: a step of mixing a halide solid electrolyte, a coating monomer, and a solvent, and allowing the coating monomer to self-polymerize on the surface of the halide solid electrolyte to form a coating layer, thereby obtaining a composite material; wherein the coating monomer contains catecholamine and its derivatives. Composite material manufacturing methods.

7. a mass ratio of the halide solid electrolyte to the coating monomer of 70:(1 to 8); The method of claim 6.

8. the catecholamine includes one or more of 3,4-dihydroxyphenylethylamine, (R)-4-(2-(methylamino)-1-hydroxyethyl]-1,2-benzenediol, and 1-(3,4-dihydroxyphenyl)-2-aminoethanol; The method according to claim 6 or 7.

9. The step of mixing a halide solid electrolyte, a coating monomer, and a solvent, and causing the coating monomer to self-polymerize on the surface of the halide solid electrolyte to form a coating layer to obtain a composite material, includes: dispersing the halide solid electrolyte in the solvent to obtain an electrolyte dispersion; mixing the electrolyte dispersion with a buffer solution having a pH of 7.5 to 8.5 to form a mixed system, and then adding an alkaline substance to adjust the pH of the mixed system to 8.5 to 8.8; adding the coating monomer to the mixed system, and carrying out a reaction while controlling the pH of the mixed system to be maintained at 8.5 to 8.8, and then centrifuging and drying the reaction product to obtain a composite material. The method according to any one of claims 6 to 8.

10. In the step of dispersing the halide solid electrolyte in the solvent to obtain an electrolyte dispersion, the concentration of the halide solid electrolyte in the electrolyte dispersion is 0.2 to 1 g / ml. The method of claim 9.

11. In the step of dispersing the halide solid electrolyte in the solvent to obtain an electrolyte dispersion, the solvent includes at least one of n-heptane, n-hexane, ethanol, methanol, isopropanol, ethylene glycol, or ether. The method according to claim 9 or 10.

12. In the step of mixing the electrolyte dispersion with a buffer solution having a pH of 7.5 to 8.5 to form a mixed system, and then adding an alkaline substance to adjust the pH of the mixed system to 8.5 to 8.8, The buffer solution includes at least one of Tris-HCl buffer, 4-hydroxyethylpiperazineethanesulfonic acid, N-tris(hydroxymethyl)methylglycine, phosphoric acid, citric acid, carbonic acid, acetic acid, and barbituric acid; The method according to any one of claims 9 to 11.

13. The mass ratio of the halide solid electrolyte to the buffer solution is 70:(1 to 4), The method according to any one of claims 9 to 12.

14. the alkaline substance comprises one or more of an inorganic base or an organic base; the inorganic base is at least one selected from the group consisting of alkali metal oxides, alkali metal hydroxides, alkali metal bicarbonates, alkali metal carbonates, alkaline earth metal oxides, alkaline earth metal hydroxides, and alkaline earth metal bicarbonates; The organic base is at least one selected from the group consisting of an alkali metal salt of an organic acid, an alkali metal salt of an alcohol, an alkylamine compound, and an alkylammonium hydroxide. The method according to any one of claims 9 to 13.

15. In the step of adding the coating monomer to the mixed system, and carrying out a reaction while controlling the pH of the mixed system to be maintained at 8.5 to 8.8, and then centrifuging and drying the reaction product to obtain a composite material, The reaction is carried out at a temperature of 20 to 80°C, The reaction is carried out for 0.5 to 24 hours. The method according to any one of claims 9 to 14.

16. In the step of adding the coating monomer to the mixed system, and carrying out a reaction while controlling the pH of the mixed system to be maintained at 8.5 to 8.8, and then centrifuging and drying the reaction product to obtain a composite material, The reaction product is centrifuged at a rotation speed of 2000 to 15000 r / min for 2 to 5 minutes. The method according to any one of claims 9 to 15.

17. the step of mixing a halide solid electrolyte, a coating monomer, and a solvent, and causing the coating monomer to self-polymerize on the surface of the halide solid electrolyte to form a coating layer to obtain a composite material, is carried out in an inert atmosphere containing one or more of nitrogen gas, helium gas, and argon gas; The method according to any one of claims 9 to 16.

18. A battery comprising a positive electrode, a thin solid electrolyte film, and a negative electrode, wherein the material of the thin solid electrolyte film comprises the composite material according to any one of claims 1 to 5 or a composite material produced by the production method according to any one of claims 6 to 17. Lithium battery.

Images