Solid electrolyte and preparation method and application thereof, and modified positive electrode material and preparation method and application thereof

Abstract

The invention relates to the technical field of electrolyte preparation, in particular to a solid electrolyte and a preparation method and application thereof, and a modified positive electrode material and a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing a lithium source, a metal halogen compound and a solvent, and uniformly stirring to obtain a mixed material; the solvent comprises water and an organic solvent, and the mass content of the water in the solvent is 5%-10%; (2) heating the mixed material, and drying to obtain a solid electrolyte precursor; and (3) microwave sintering. The solid electrolyte precursor is prepared by adopting a wet process, the batch consistency of the solid electrolyte is remarkably improved and the synthesis efficiency is improved by matching with a microwave sintering technology, the preparation of the solid electrolyte with high compactness and uniform grain size is facilitated, and the ionic conductivity is greater than 5mS / cm and is remarkably higher than that of the solid electrolyte prepared by a traditional ball milling method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrolyte preparation, and particularly relates to a solid-state electrolyte and a preparation method and application thereof, and a modified positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the increasing demand for high energy density and high safety batteries, solid-state batteries have become a research hotspot. As a core component of solid-state batteries, solid-state electrolytes need to have ion conductivity, electrochemical stability and compatibility with electrode materials. Halide electrolytes have gradually become an important direction for the innovation of solid-state battery material systems due to their unique advantages.

[0003] The preparation methods of halide electrolytes mainly include high-energy ball milling, solid-phase sintering and liquid-phase synthesis. The product consistency of high-energy ball milling is poor, and the heat generated during ball milling will form a large amount of amorphous silicon phase or low crystallinity phase, which affects the purity of the product and leads to poor calendar life. The solid-phase sintering method has batch differences in raw material ratio and regional temperature, resulting in different electrolyte performances. The liquid-phase synthesis method has a narrow application range and is only suitable for the synthesis of a small number of electrolytes such as Li3InCl6 and Li3YCl6.

[0004] In order to improve the positive electrode material, a coating layer is usually formed on the surface of the positive electrode. The uniformity and density of the coating layer formed by the traditional ball milling method need to be improved, which poses a challenge to the surface modification technology of the positive electrode. Although the existing physical vapor deposition and atomic layer deposition methods can achieve uniform coating, the equipment cost is high and the process is complex, which makes it difficult to be applied on a large scale. In addition, the conventional coating materials such as LiNbO3 and LiPO4 have low ion conductivity (10 -6 ~ 10 -8 S / cm), which seriously hinders the lithium ion transmission on the positive electrode side and affects the cycle and rate performance of the battery. SUMMARY

[0005] One of the purposes of the present application is to provide a preparation method of a solid-state electrolyte to solve the problems of existing solid-state electrolytes, such as the presence of a large amount of amorphous silicon phase or low crystallinity phase and batch differences leading to different electrolyte performances.

[0006] The second purpose of the present application is to provide a modified positive electrode material to solve the problems of poor lithium ion transmission on the positive electrode side and poor cycle and rate performance of the battery.

[0007] In order to achieve the above purposes, the technical solutions adopted by the present application are as follows:

[0008] The first aspect of the present application provides a preparation method of a solid-state electrolyte, comprising:

[0009] (1) mixing lithium source, metal halogen compound and solvent to obtain a mixture, wherein the solvent comprises water and organic solvent, and the mass content of water in the solvent is 5-10%;

[0010] (2) heating the mixture to obtain a solid-state electrolyte precursor after drying;

[0011] (3) microwave sintering.

[0012] According to the above technical means, the solid-state electrolyte precursor is prepared by using the wet process, and the microwave sintering technology is used, so that the batch consistency of the solid-state electrolyte is significantly improved, the synthesis efficiency is improved, the solid-state electrolyte with high density and uniform grain size is prepared, and the ionic conductivity is > 5 mS / cm, which is significantly higher than that of the solid-state electrolyte prepared by the traditional ball milling method. When the solid-state electrolyte is prepared by the traditional ball milling method, heat is generated during the ball milling process, and part of the amorphous phase or low crystallinity phase is formed. During the annealing process, the solid-state electrolyte obtained has many impurities and relatively low purity. In the present application, the metal halogen compound and lithium source are dissolved in the solvent containing water, the metal halogen compound reacts with water to form an oxide, and the oxide reacts with the lithium source and the metal halogen compound under the action of microwave to form an oxyhalide. This reaction process can fully mix the raw materials, further control the water content in the solvent, react the metal halogen compound with water, use the product to further synthesize the solid-state electrolyte, avoid the excessive water from reacting with the product to generate HCl, inhibit the hydrolysis reaction of the product, and compared with the traditional ball milling and solid-phase sintering method, the present application can reduce the energy consumption, avoid the heat generated by ball milling from affecting the purity and service life of the product, has higher efficiency, better consistency of the product, and better density and size uniformity of the solid-state electrolyte.

[0013] For example, the mass content of water in the solvent is 5%, 6%, 7%, 8%, 9%, 10%, etc.

[0014] Further, the parameters of the microwave sintering are as follows: the frequency is 1-3 GHz;

[0015] and / or, the temperature is 100-300℃;

[0016] and / or, the time is 3-6h;

[0017] and / or, the drying temperature is 75-85℃.

[0018] According to the above technical means, the microwave sintering parameters meet the above range, can realize overall uniform heating, and help the product consistency; suitable heating time and temperature can reduce the generation of impurities, and further ensure the material performance, such as density, size uniformity, etc. As an example, the frequency is 1GHz, 1.5GHz, 2GHz, 2.5GHz, 3GHz, etc.; the temperature is 100℃, 150℃, 200℃, 250℃, 300℃, etc.; the time is 3h, 4h, 5h, 6h, etc.; the drying temperature is 75℃, 77℃, 80℃, 82℃, 85℃, etc. Before drying, the heating temperature can be the same as or different from the drying temperature, for example, the heating temperature can be 40-65℃, etc., and the present application does not make specific requirements thereon.

[0019] Further, the lithium source includes at least one of lithium carbonate, lithium hydroxide, lithium chloride; preferably, the lithium source includes lithium chloride;

[0020] And / or, the metal halide compound includes a metal chloride; preferably, the metal chloride includes at least one of aluminum chloride, zinc chloride, copper chloride, iron trichloride, magnesium chloride, niobium pentachloride; more preferably, the metal chloride includes niobium pentachloride.

[0021] Take niobium chloride as an example to illustrate the reaction principle of the preparation method:

[0022] 2NbCl5+5H2O=Nb2O5+10HCl; this step represents that the metal halide compound and water react to generate an oxide;

[0023] 3NbCl5+Nb2O5+5LiCl=5LiNbOCl4; this step represents that the oxide generated in the above step, the metal halide compound and the lithium source react to generate an oxyhalide.

[0024] According to the above technical means, the above raw materials can be effectively dissolved in the organic solvent to form a uniform solution, and improve the product consistency.

[0025] Further, the molar ratio of the metal halide compound to the lithium salt is 1:(0.5-2);

[0026] And / or, the molar ratio of the metal halide compound to the solvent water is 1:(0.8-1);

[0027] And / or, the organic solvent includes at least one of dimethylformamide, dimethylacetamide, hexamethylphosphoramide, N-methylpyrrolidone, dimethyl sulfoxide.

[0028] According to the above technical means, the above raw materials can be selected to remove ppm-level water in the solvent, and avoid the reaction of the synthetic product with a small amount of water. As an example, the metal in the metal halide compound includes at least one of Al, Zn, Cu, Fe, Mg, and Nb, the molar ratio of the metal halide compound and the lithium salt is 1:0.5, 1:1, 1:1.5, 1:2, etc., and the molar ratio of the metal halide compound and water is 1:0.8, 1:0.9, 1:1, etc.

[0029] Further, the second aspect of the present application provides a solid-state electrolyte prepared by the above method, and the solid-state electrolyte has a structural formula Li a M b Cl 6-2x O c ; M is selected from at least one of Al, Zn, Cu, Fe, Mg, and Nb, 1≤a≤3, 1≤b≤3, and 0≤c≤2.

[0030] Further, the third aspect of the present application provides a preparation method of a modified positive electrode material, including:

[0031] (1) mixing the metal halide compound and the positive electrode material with a solvent, heating, and drying to obtain a positive electrode precursor; the solvent includes water and an organic solvent, and the mass ratio of water in the solvent is 5%-10%;

[0032] (2) microwave sintering.

[0033] The positive electrode material has residual alkali on the surface, which hinders the lithium ion transmission capacity on the positive electrode side, increases the internal resistance of the battery, and reduces the performance of the battery. According to the above technical means, the present application discards the traditional physical vapor deposition and atomic layer deposition and other expensive technologies when preparing the positive electrode material, and first dissolves the positive electrode material and the metal halide compound in the solvent. The residual alkali on the surface of the positive electrode can be used as raw material to modify the surface of the positive electrode material, and the metal halide compound is uniformly coated on the surface of the positive electrode by a liquid phase method. The process includes forming a solid-state electrolyte precursor on the surface of the positive electrode material by using a wet process, and forming a coating layer containing a solid-state electrolyte on the surface of the positive electrode material by using a microwave sintering method. The coating layer has the advantages of high density and uniformity, reduces the production cost, simplifies the process flow, improves the ion conductivity and interface transmission capacity of the positive electrode material, reduces the interface side reaction, and significantly improves the cycle stability and rate performance of the battery.

[0034] Further, the mass ratio of the metal halide compound to the positive electrode material is 1:(53.8-54.9); as an example, the mass ratio is 1:53.8, 1:53.9, 1:54, 1:54.5, 1:54.7, 1:54.9, etc.

[0035] And / or, the organic solvent comprises at least one of dimethylformamide, dimethylacetamide, hexamethylphosphoramide, N-methylpyrrolidone, dimethyl sulfoxide;

[0036] And / or, the molar ratio of the metal halogen compound and water is 1:(0.8-1); for example, the molar ratio of the metal halogen compound and water is 1:0.8, 1:0.9, 1:1, etc.

[0037] And / or, the temperature of the drying is 75-85℃; for example, the temperature of the drying is 75℃, 77℃, 80℃, 82℃, 85℃, etc. The temperature of the heating before the drying can be the same as or different from the temperature of the drying, for example, the temperature of the heating can be 40-65℃, etc. The present application does not make specific requirements thereon.

[0038] And / or, the positive electrode material comprises a compound with a structural formula of LiNi 1-x-y Co x Mn y O2, wherein 0

[0039] And / or, the metal halogen compound comprises a metal chloride; preferably, the metal chloride comprises at least one of aluminum chloride, zinc chloride, copper chloride, iron trichloride, magnesium chloride, and niobium pentachloride; more preferably, the metal chloride comprises niobium pentachloride.

[0040] And / or, the parameters of the microwave sintering are: the frequency is 1-3GHz; and / or, the temperature is 100-300℃; and / or, the time is 3-6h. For example, the frequency is 1GHz, 1.5GHz, 2GHz, 2.5GHz, 3GHz, etc.; the temperature is 100℃, 150℃, 200℃, 250℃, 300℃, etc.; and the time is 3h, 4h, 5h, 6h, etc.

[0041] According to the above technical means, the present application adjusts the parameters of the microwave sintering to meet the above range, which is beneficial to form a stable phase, reduce impurities of the product, and improve the performance. When the temperature or frequency of the microwave sintering is too high, part of the raw materials will be decomposed, which affects the performance of the product; when the temperature or frequency is too low, the generation rate of the target product will be reduced; when the time of the microwave sintering is too short, there are relatively more impurities, which affects the performance of the positive electrode material; and when the time of the microwave sintering is too long, the stability of the phase is not good, and the structure is easy to change.

[0042] Further, the present application provides a positive electrode material prepared by the above method.

[0043] Further, the present application provides a positive electrode material prepared by the above method.

[0044] The solid-state electrolyte prepared by the specific method is combined with the modified positive electrode material to improve the interface performance on the positive electrode side, thereby improving the electrochemical performance of the battery, and providing technical support for the large-scale production of the solid-state battery.

[0045] Further, the application provides a battery comprising the positive electrode sheet.

[0046] The application has the following advantages:

[0047] 1. The preparation method of the solid-state electrolyte provided by the application comprises the following steps: (1) mixing a lithium source, a metal halide compound and a solvent, and stirring uniformly to obtain a mixture; the solvent comprises water and an organic solvent, and the mass content of water in the solvent is 5%-10%; (2) heating the mixture, and obtaining a solid-state electrolyte precursor after drying; and (3) microwave sintering. The solid-state electrolyte precursor is prepared by using a wet process, and the microwave sintering technology is combined to significantly improve the batch consistency of the solid-state electrolyte, improve the synthesis efficiency, and be beneficial to the preparation of the solid-state electrolyte with high density and uniform grain size, and the ionic conductivity is greater than 5 mS / cm, which is significantly higher than that of the solid-state electrolyte prepared by a traditional ball milling method. When the solid-state electrolyte is prepared by the traditional ball milling method, heat is generated in the ball milling process, and part of the amorphous phase or low crystallinity phase is formed, and the solid-state electrolyte obtained in the annealing process has many impurities and relatively low purity. In the application, the metal halide compound and the lithium source are dissolved in the solvent containing water, the metal halide compound reacts with water to generate an oxide, the oxide, the lithium source and the metal halide compound are uniformly heated under the microwave condition to generate an oxyhalide, the reaction process can fully mix the raw materials, the water content in the solvent is further adjusted, the metal halide compound can react with water, the product generated by the reaction can be used to further synthesize the solid-state electrolyte, the generation of HCl can be avoided by avoiding the excessive reaction of water with the product, the hydrolysis reaction of the product is inhibited, compared with the traditional ball milling and solid-phase sintering method, the energy consumption of the application can be further reduced, the purity and service life of the product can be avoided by avoiding the heat generated by the ball milling, the efficiency is higher, the consistency of the product is better, and the density and size uniformity of the solid-state electrolyte are better.

[0048] 2. The preparation method of the solid-state electrolyte provided by the application can realize uniform heating as a whole by adjusting the temperature, frequency and time of microwave sintering, which is helpful to the consistency of the product; and appropriate heating time and temperature can reduce the generation of impurities and further ensure the performance of the material, such as the density and size uniformity.

[0049] 3. The preparation method of the modified positive electrode material provided by the present application comprises the following steps: (1) mixing a metal halogen compound, a positive electrode material and a solvent, heating and drying to obtain a positive electrode precursor; the solvent comprises water and an organic solvent, and the mass ratio of water in the solvent is 5%-10%; (2) microwave sintering. The positive electrode material has residual alkali on the surface, which hinders the lithium ion transmission capacity of the positive electrode side, increases the internal resistance of the battery and reduces the performance of the battery. According to the above technical means, when the positive electrode material is prepared, the traditional physical vapor deposition and atomic layer deposition and other expensive technologies are abandoned, the positive electrode material and the metal halogen compound are dissolved in the solvent, the residual alkali on the surface of the positive electrode can be innovatively used as a raw material to serve as a lithium source, the surface of the positive electrode material is modified, the metal halogen compound is uniformly coated on the surface of the positive electrode through a liquid phase method, the process comprises forming a solid electrolyte precursor on the surface of the positive electrode material by using a wet process, and a microwave sintering method is used to form a coating layer containing a solid electrolyte on the surface of the positive electrode material, the formed coating layer has the advantages of high density and uniformity, the production cost is reduced, the process flow is simplified, the ion conductivity and interface transmission capacity of the positive electrode material are improved, the interface side reaction is reduced, and the cycle stability and rate performance of the battery are significantly improved.

[0050] 4. The preparation method of the modified positive electrode material provided by the present application, the microwave sintering parameters are adjusted, which is beneficial to form a stable phase, reduce impurities of the product and improve performance. When the microwave sintering temperature or frequency is too high, part of the raw materials will be decomposed, which affects the performance of the product; when the temperature or frequency is too low, the generation rate of the target product will be reduced; when the microwave sintering time is too short, there are relatively more impurities, which affects the performance of the positive electrode material; and when the microwave sintering time is too long, the stability of the phase is not good and the structure is easy to change.

[0051] 5. The positive electrode sheet provided by the present application comprises the solid electrolyte and the modified positive electrode material provided by the present application. The solid electrolyte prepared by using the specific method is combined with the modified positive electrode material provided by the present application, so that the interface performance on the positive electrode side can be improved, the electrochemical performance of the battery is improved, technical support is provided for the large-scale production of solid-state batteries, the preparation method of the modified positive electrode material provided by the present application has the advantages of simple process, low cost and easy industrialization, and provides an important technical breakthrough for the research and application of high-energy-density and high-safety solid-state batteries, and has a wide application prospect and market value. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 FIG. 1 is a TEM diagram of the modified positive electrode material of Example 1 of the present application;

[0053] Figure 2 FIG. 1 is a TEM diagram of the modified positive electrode material of Example 1 of the present application; DETAILED DESCRIPTION

[0054] The present application is herein described, by way of example only, with reference to the accompanying drawings. It is to be understood that various modifications can be made to the embodiments described and illustrated herein, without departing from the scope of the present application, which is defined by the appended claims. The preferred embodiments are for purposes of illustration only and the application is not limited to those precise embodiments and various other ways of practicing the application are possible from the disclosure herein without departing from the spirit or scope of the application.

[0055] It is also to be understood that the following description is only illustrative of the aspects and embodiments of the present application and is not intended to be limiting. The description of the preferred embodiments together with the accompanying drawings are intended to explain the principles of the application and the application is limited only by the claims.

[0056] Example 1

[0057] The present embodiment provides a method for preparing a solid-state electrolyte, comprising the following steps:

[0058] 0.9 g of deionized water and 10.01 g of dimethyl sulfoxide were weighed and continuously stirred for 3 h, then 13.508 g of NbCl5 and 2.1196 g of LiCl were dissolved in 10.91 g of the above-mentioned dimethyl sulfoxide mixed solution, and continuously stirred on a 50°C heating platform for 10 h to form a uniform precursor solution. The precursor solution was placed in an oven at 80°C for 24 h, and after the solvent was removed, a powder material, i.e. a solid-state electrolyte precursor, was obtained. Finally, the precursor material was placed in a microwave sintering furnace for microwave synthesis, with a synthesis temperature of 200°C, a microwave frequency of 2.4 GHz, and a holding time of 4 h.

[0059] The present embodiment also provides a modified positive electrode material, comprising the following steps:

[0060] 0.0914 g of NbCl5 was dissolved in 0.0738 g of the above-mentioned dimethyl sulfoxide mixed solution, and 5 g of NCM positive electrode was added and stirred for 2 h, then continuously stirred on a 50°C heating platform for 10 h to obtain a modified positive electrode precursor solution. The precursor solution was placed in an oven at 80°C for 24 h, and after the solvent was removed, a powder material, i.e. a modified positive electrode precursor, was obtained. The modified positive electrode precursor was placed in a microwave sintering furnace for positive electrode localized in-situ deposition, with a deposition temperature of 200°C, a microwave frequency of 2.4 GHz, and a holding time of 4 h.

[0061] The embodiment provides a battery, which comprises the modified positive electrode material, the solid-state electrolyte and conductive carbon black which are uniformly mixed according to a mass ratio of 80:16:4 to obtain a composite positive electrode powder. The composite positive electrode powder, a sulfide electrolyte LPSC and a Li-In alloy negative electrode are sequentially assembled into a mold battery, and the assembly pressure is 300 MPa.

[0062] Embodiment 2

[0063] The embodiment provides a preparation method of a solid-state electrolyte, which comprises the following steps:

[0064] 0.72g of deionized water and 10.208g of dimethyl sulfoxide are weighed, continuously stirred for 3h, then 10.8064g of NbCl5 and 1.6956g of LiCl are dissolved in 10.928g of the mixed dimethyl sulfoxide solution, continuously stirred on a 50 DEG C heating platform for 10h to form a uniform precursor solution. The precursor solution is placed in an oven at 80 DEG C for 24h, and after the solvent is removed, a powder material, i.e., a solid-state electrolyte precursor, is obtained. Finally, the precursor material is placed in a microwave sintering furnace for microwave synthesis, the synthesis temperature is 180 DEG C, the microwave frequency is 2.2GHz, and the holding time is 3h.

[0065] The embodiment also provides a modified positive electrode material, which comprises the following steps:

[0066] 0.0914g of NbCl5 is dissolved in 0.0924g of the mixed dimethyl sulfoxide solution, 5g of an NCM positive electrode is added and stirred for 2h, then continuously stirred on a 50 DEG C heating platform for 10h to obtain a modified positive electrode precursor solution. The precursor solution is placed in an oven at 80 DEG C for 24h, and after the solvent is removed, a powder material, i.e., a modified positive electrode precursor, is obtained. The modified positive electrode precursor is placed in a microwave sintering furnace for positive electrode local in-situ deposition, the deposition temperature is 200 DEG C, the microwave frequency is 2.4GHz, and the holding time is 4h.

[0067] The embodiment also provides a battery, and the preparation method is the same as that in Embodiment 1.

[0068] Embodiment 3

[0069] The embodiment provides a preparation method of a solid-state electrolyte, which comprises the following steps:

[0070] Take 1.08 g of deionized water and 9.812 g of dimethyl sulfoxide, continuously stir for 3 h, then dissolve 16.2096 g of NbCl5, 2.5435 g of LiCl in 10.892 g of the above dimethyl sulfoxide mixed solution, continuously stir for 10 h on a 50°C heating platform, and form a uniform precursor solution. The precursor solution is placed in an oven at 80°C for 24 h, and after the solvent is removed, a powder material, i.e. a solid electrolyte precursor, is obtained. Finally, the precursor material is placed in a microwave sintering furnace for microwave synthesis, with a synthesis temperature of 260°C, a microwave frequency of 2.8 GHz, and a holding time of 6 h.

[0071] The embodiment also provides a modified positive electrode material, including the following steps:

[0072] Dissolve 0.0914 g of NbCl5 in 0.0614 g of the above dimethyl sulfoxide mixed solution, add 5 g of NCM positive electrode and stir for 2 h, then continuously stir for 10 h on a 50°C heating platform to obtain a modified positive electrode precursor solution. The precursor solution is placed in an oven at 80°C for 24 h, and after the solvent is removed, a powder material, i.e. a modified positive electrode precursor, is obtained. The modified positive electrode precursor is placed in a microwave sintering furnace for positive electrode local in-situ deposition, with a deposition temperature of 200°C, a microwave frequency of 2.4 GHz, and a holding time of 4 h.

[0073] The embodiment also provides a battery, and the preparation method is the same as that of Example 1.

[0074] Example 4

[0075] The embodiment provides a preparation method of a solid electrolyte, and the preparation method is the same as that of Example 1.

[0076] The embodiment also provides a modified positive electrode material, including the following steps:

[0077] Dissolve 0.0768 g of NbCl5 in 0.062 of the above dimethyl sulfoxide mixed solution, add 4.2 g of NCM positive electrode and stir for 2 h, then continuously stir for 10 h on a 50°C heating platform to obtain a modified positive electrode precursor solution. The precursor solution is placed in an oven at 80°C for 24 h, and after the solvent is removed, a powder material, i.e. a modified positive electrode precursor, is obtained. The modified positive electrode precursor is placed in a microwave sintering furnace for positive electrode local in-situ deposition, with a deposition temperature of 180°C, a microwave frequency of 2.2 GHz, and a holding time of 3 h.

[0078] The embodiment also provides a battery, and the preparation method is the same as that of Example 1.

[0079] Example 5

[0080] The embodiment provides a preparation method of a solid electrolyte, and the preparation method is the same as that of Example 1.

[0081] The embodiment also provides a modified positive electrode material, comprising the following steps:

[0082] 0.1024 g of NbCl5 is dissolved in 0.0827 g of the above dimethyl sulfoxide mixed solution, 5.6 g of NCM positive electrode is added, stirred for 2 h, and then continuously stirred at a heating platform of 50 DEG C for 10 h to obtain a modified positive electrode precursor solution. The precursor solution is placed in an oven at 80 DEG C for 24 h, and after the solvent is removed, a powder material, i.e., a modified positive electrode precursor, is obtained. The modified positive electrode precursor is placed in a microwave sintering furnace, and positive electrode local in-situ deposition is carried out, the deposition temperature is 260 DEG C, the microwave frequency is 2.8 GHz, and the holding time is 6 h.

[0083] The embodiment also provides a battery, and the preparation method is the same as that in the embodiment 1.

[0084] Embodiment 6

[0085] The embodiment provides a preparation method of a solid-state electrolyte, which is basically the same as that in the embodiment 1, except that the same molar amount of FeCl3 is used instead of NbCl5.

[0086] The embodiment also provides a modified positive electrode material, which is basically the same as that in the embodiment 1, except that FeCl3 is used instead of NbCl5, the molar amount of FeCl3 to water in dimethyl sulfoxide is 1:1, the mass ratio of FeCl3 to NCM is 1:54.7, and the other steps are the same as those in the embodiment 1.

[0087] The embodiment also provides a battery, and the solid-state electrolyte is used, and the other steps are the same as those in the embodiment 1.

[0088] Embodiment 7

[0089] The embodiment provides a preparation method of a solid-state electrolyte, which is basically the same as that in the embodiment 1, except that the same molar amount of MgCl2 is used instead of NbCl5.

[0090] The embodiment also provides a modified positive electrode material, which is basically the same as that in the embodiment 1, except that MgCl2 is used instead of NbCl5, the molar amount of MgCl2 to water in dimethyl sulfoxide is 1:1, the mass ratio of MgCl2 to NCM is 1:54.7, and the other steps are the same as those in the embodiment 1.

[0091] The embodiment also provides a battery, and the solid-state electrolyte is used, and the other steps are the same as those in the embodiment 1.

[0092] Embodiment 8

[0093] The embodiment provides a preparation method of a solid-state electrolyte, which is basically the same as that in the embodiment 1, except that the same molar amount of ZnCl2 is used instead of NbCl5.

[0094] The embodiment also provides a modified positive electrode material, which is basically the same as that in Embodiment 1, except that ZnCl2 is used to replace NbCl5, the molar ratio of ZnCl2 to water in dimethyl sulfoxide is 1:1, the mass ratio of ZnCl2 to NCM is 1:54.7, and the other conditions are the same as in Embodiment 1.

[0095] The embodiment also provides a battery, which uses the solid electrolyte in the embodiment and is basically the same as that in Embodiment 1.

[0096] Embodiment 9

[0097] The embodiment provides a preparation method of a solid electrolyte, which is basically the same as that in Embodiment 1, except that AlCl3 is used to replace NbCl5.

[0098] The embodiment also provides a modified positive electrode material, which is basically the same as that in Embodiment 1, except that AlCl3 is used to replace NbCl5, the molar ratio of AlCl3 to water in dimethyl sulfoxide is 1:1, the mass ratio of AlCl3 to NCM is 1:54.7, and the other conditions are the same as in Embodiment 1.

[0099] The embodiment also provides a battery, which uses the solid electrolyte in the embodiment and is basically the same as that in Embodiment 1.

[0100] Embodiment 10

[0101] The embodiment provides a preparation method of a solid electrolyte, which is basically the same as that in Embodiment 1, except that CuCl2 is used to replace NbCl5.

[0102] The embodiment also provides a modified positive electrode material, which is basically the same as that in Embodiment 1, except that CuCl2 is used to replace NbCl5, the molar ratio of CuCl2 to water in dimethyl sulfoxide is 1:1, the mass ratio of CuCl2 to NCM is 1:54.7, and the other conditions are the same as in Embodiment 1.

[0103] The embodiment also provides a battery, which uses the solid electrolyte in the embodiment and is basically the same as that in Embodiment 1.

[0104] Embodiment 11

[0105] The embodiment provides a preparation method of a solid electrolyte, which is basically the same as that in Embodiment 1, except that NbBr5 is used to replace NbCl5.

[0106] The embodiment also provides a modified positive electrode material, which comprises the following steps:

[0107] 0.0914 g of NbBr5 is dissolved in 0.0412 g of the above-mentioned dimethyl sulfoxide mixed solution, 5 g of LiNi 0.6 Co0.2 Mn 0.2 O2positive electrode After stirring for 2 h, the modified positive electrode precursor solution was obtained after continuous stirring for 10 h on a 50 °C heating platform. The precursor solution was placed in an oven at 80 °C for 24 h, and after removing the solvent, a powder material, i.e., the modified positive electrode precursor, was obtained. The modified positive electrode precursor was placed in a microwave sintering furnace for positive electrode local in-situ deposition, with a deposition temperature of 200 °C, a microwave frequency of 2.4 GHz, and a holding time of 4 h.

[0108] The present embodiment provides a battery, which comprises: the modified positive electrode material, the solid-state electrolyte, and conductive carbon black, which are uniformly mixed in a mass ratio of 80:16:4 to obtain a composite positive electrode powder. The sulfide electrolyte, the composite positive electrode, and the Li-In negative electrode are sequentially assembled into a mold battery, and the assembly pressure is 300 MPa.

[0109] Comparative Example 1

[0110] The present comparative example provides a preparation method of a solid-state electrolyte, which comprises:

[0111] 6.8155 g of ZnCl2, 4.0705 g of ZnO, and 2.1196 g of LiCL were weighed and placed in a ball milling tank, with a ball-to-material ratio of 10:1 and a rotation speed of 300 rpm / min. After ball milling for 12 h, the mixed powder, i.e., the solid-state electrolyte precursor, was taken out. Finally, the precursor material was placed in a microwave sintering furnace for microwave synthesis, with a synthesis temperature of 200 °C, a microwave frequency of 2.4 GHz, and a holding time of 4 h.

[0112] The present comparative example provides a modified positive electrode material, which is prepared by using the modified positive electrode material prepared in Example 8.

[0113] The present comparative example provides a battery, which uses the solid-state electrolyte prepared in the present comparative example, and the other components are the same as in Example 8.

[0114] Comparative Example 2

[0115] The present comparative example provides a preparation method of a solid-state electrolyte, which comprises:

[0116] 0.9 g of deionized water and 10.01 g of dimethyl sulfoxide were weighed and continuously stirred for 3 h, and then 6.8155 g of ZnCl2and 2.1196 g of LiCL were dissolved in 10.91 g of the above-mentioned dimethyl sulfoxide mixed solution. After continuous stirring for 10 h on a 50 °C heating platform, a uniform precursor solution was formed. The precursor solution was placed in an oven at 80 °C for 24 h, and after removing the solvent, a powder material, i.e., the solid-state electrolyte precursor, was obtained. Finally, the precursor material was placed in a high-temperature sintering furnace for sintering synthesis, with a sintering synthesis temperature of 200 °C and a holding time of 4 h.

[0117] The comparative example provides a modified positive electrode material, which is prepared by using the modified positive electrode material prepared in Example 8.

[0118] The comparative example provides a battery, which is prepared by using the solid-state electrolyte prepared in the comparative example, and the others are the same as in Example 8.

[0119] Comparative Example 3

[0120] The comparative example provides a preparation method of a solid-state electrolyte, which is the same as in Comparative Example 1.

[0121] The comparative example provides a modified positive electrode material, which comprises the following steps:

[0122] 0.0231 g of ZnCl2 is dissolved in 0.0369 g of the above dimethyl sulfoxide mixed solution, 5 g of NCM positive electrode is added and stirred for 2 h, and then continuously stirred at a heating platform of 50 °C for 10 h to obtain a modified positive electrode precursor solution. The precursor solution is placed in an oven at 80 °C for 24 h, and after the solvent is removed, a powder material, i.e. a modified positive electrode precursor, is obtained. Finally, the precursor material is placed in a high-temperature sintering furnace for sintering, the sintering temperature is 200 °C, and the holding time is 4 h.

[0123] The comparative example provides a battery, which is prepared by using the modified positive electrode material prepared in the comparative example, and the others are the same as in Comparative Example 1.

[0124] Test Example

[0125] The test example provides the performance of the batteries of each example and comparative example, and the test results are as follows:

[0126] Test method of ionic conductivity: the solid-state electrolyte prepared in each example and comparative example is assembled into a stainless steel symmetrical battery, the assembled battery is placed under the condition of 300 MPa for testing, an electrochemical workstation is used to test the electrochemical impedance of the battery at room temperature, the test frequency range is 1 Hz-1 MHz, the perturbation amplitude is 10 mV, and the alternating current impedance R of the battery is tested. The ionic conductivity σ is calculated by the formula σ=d / RS, wherein d is the thickness of the electrolyte, R is the alternating current impedance, and S is the area of the electrolyte.

[0127] Test method of battery impedance: the battery obtained in each example and comparative example is tested under the condition of 100 MPa, an electrochemical workstation is used to test the electrochemical impedance of the battery at room temperature, the test frequency range is 1 Hz-1 MHz, the perturbation amplitude is 10 mV, and the alternating current impedance R of the battery is tested.

[0128] Test method of charge-discharge cycle performance: the battery obtained in each example and comparative example is subjected to battery charge-discharge at 25 °C and 0.33 C rate, and the capacity retention rate is calculated after 100 cycles. The capacity retention rate is the ratio of the discharge capacity of the 100th cycle to the discharge capacity of the 1st cycle.

[0129] Table 1 test results

[0130]

[0131] From the above test results, it can be seen that in the preparation of the solid-state electrolyte, the wet process is used to obtain the solid-state electrolyte precursor first, and the microwave sintering technology is used, which can improve the density and grain size uniformity of the solid-state electrolyte, and the ion conductivity is high, and when applied to the battery, the battery impedance and cycle performance can be improved. In the preparation of the modified positive electrode material, according to the process of the present application, the cycle performance of the battery can be further improved and the impedance can be reduced. Compared with the traditional ball milling process and the solid phase sintering process, the solid-state electrolyte prepared by the method of the present application has better performance, and when applied to the battery, it has better cycle performance and low impedance. From the examples, the performance of niobium pentachloride as a metal halide compound is the best.

[0132] Figure 1 is the TEM diagram of the modified positive electrode material of Example 1 of the present application, a is the TEM diagram of the positive electrode material NCM, and b is the TEM diagram of the modified positive electrode material after coating. As can be seen from the diagram, the positive electrode material NCM has a uniform coating layer on the surface, and the coating layer is uniform and dense. Figure 2 is the TEM diagram of the modified positive electrode material prepared in Comparative Example 3, and the coating layer formed on the surface of the modified positive electrode material is not uniform and is discontinuous. From Figure 1 and Figure 2 , according to the process of the present application, the modified positive electrode material can form a uniform coating layer containing solid-state electrolyte on the surface of the positive electrode material, and the coating layer has good density. According to the data in Table 1, the modified positive electrode material is applied to the battery, which can improve the ion conductivity, reduce the impedance, and improve the cycle performance of the battery.

[0133] The above examples are only preferred examples for fully illustrating the present application, and the protection scope of the present application is not limited thereto. Any equivalent replacement or transformation made by those skilled in the art on the basis of the present application is within the protection scope of the present application.

Claims

1. A method of preparing a solid state electrolyte, characterized by, Comprising: (1) mixing a lithium source, a metal halide compound and a solvent, stirring uniformly to obtain a mixture; the solvent comprises water and an organic solvent, and the mass content of water in the solvent is 5%-10%; (2) heating the mixture, and obtaining a solid-state electrolyte precursor after drying; (3) microwave sintering.

2. The production method according to claim 1, characterized by, The microwave sintering parameters are: the frequency is 1-3 GHz; and / or, the temperature is 100-300℃; and / or, the time is 3-6h; and / or, the drying temperature is 75-85℃.

3. The preparation method according to claim 1, characterized in that, The lithium source comprises at least one of lithium carbonate, lithium hydroxide and lithium chloride; preferably, the lithium source comprises lithium chloride; and / or, the metal halide compound comprises a metal chloride; preferably, the metal chloride comprises at least one of aluminum chloride, zinc chloride, copper chloride, ferric chloride, magnesium chloride and niobium pentachloride; more preferably, the metal chloride comprises niobium pentachloride.

4. The production method according to any one of claims 1 to 3, characterized by, The molar ratio of the metal halide compound to the lithium salt is 1:(0.5-2); and / or, the molar ratio of the metal halide compound to water is 1:(0.8-1); and / or, the organic solvent comprises at least one of dimethylformamide, dimethylacetamide, hexamethylphosphoramide, N-methylpyrrolidone and dimethyl sulfoxide.

5. The solid-state electrolyte produced by the production method according to any one of claims 1 to 4, characterized in that, The solid-state electrolyte has a structural formula Li a M b Cl 6-2x O c ; M is selected from at least one of Al, Zn, Cu, Fe, Mg, Nb, 1≤a≤3, 1≤b≤3, 0≤c≤2.

6. A method for producing a modified positive electrode material, characterized by, Comprising: (1) mixing a metal halide compound, a positive electrode material and a solvent, heating, and obtaining a positive electrode precursor after drying; the solvent comprises water and an organic solvent, and the mass content of water in the solvent is 5%-10%; (2) microwave sintering.

7. The production method according to claim 6, characterized by, The mass ratio of the metal halide compound to the positive electrode material is 1:(53.8-54.9); and / or, the organic solvent comprises at least one of dimethylformamide, dimethylacetamide, hexamethylphosphoramide, N-methylpyrrolidone and dimethyl sulfoxide; and / or, the molar ratio of the metal halide compound to water is 1:(0.8-1); and / or, the drying temperature is 75-85℃; and / or the cathode material comprises a compound having a structural formula LiNi 1-x-y Co x Mn y O2, wherein 0 < x < 0.5, 0 < y < 0.5; preferably, the cathode material comprises NCM811; and / or, the metal halide compound comprises a metal chloride; preferably, the metal chloride comprises at least one of aluminum chloride, zinc chloride, copper chloride, ferric chloride, magnesium chloride and niobium pentachloride; more preferably, the metal chloride comprises niobium pentachloride; and / or, the microwave sintering parameters are: the frequency is 1-3 GHz; and / or, the temperature is 100-300℃; and / or, the time is 3-6h.

8. The positive electrode material prepared by the preparation method of claim 6 or 7.

9. A positive electrode sheet characterized by comprising: Comprising the solid-state electrolyte prepared by the preparation method of any one of claims 1-4 and the modified positive electrode material prepared by the preparation method of any one of claims 6-7.

10. A battery, characterized by Comprising the positive electrode sheet of claim 9.

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