Micro-nano composite sulfide solid electrolyte and preparation method and application thereof

Abstract

The invention discloses a micro-nano composite sulfide solid electrolyte and a preparation method and application thereof. The micro-nano composite sulfide solid electrolyte comprises the following raw materials: a micron-scale sulfide solid electrolyte, a nano-scale sulfide solid electrolyte and a modified additive, the modified additive comprises modified zirconium oxide and / or modified zirconium oxide aluminum oxide; the micron-sized sulfide solid electrolyte is used as a structural main body of the micro-nano composite sulfide solid electrolyte, and the nano-sized sulfide solid electrolyte and the modified additive are distributed in the micron-sized sulfide solid electrolyte in a penetrating manner; the micron-sized sulfide solid electrolyte is prepared by adopting a ball-milling solid-phase synthesis method, and the nano-sized sulfide solid electrolyte is prepared by adopting a liquid-phase synthesis method. The micro-nano composite sulfide solid electrolyte provided by the invention has excellent high-temperature performance, rate performance, cycle performance and mechanical performance, and can be widely applied to the field of battery manufacturing.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid electrolytes, and in particular relates to a micro-nano composite sulfide solid electrolyte and a preparation method and application thereof. Background Art

[0002] Solid electrolytes have great potential in improving the safety and performance of lithium-ion batteries. Sulfide solid electrolytes have become a research hotspot due to their excellent ionic conductivity and good interface contact performance. However, there are some limitations in the use of sulfide solid electrolytes, such as unstable performance at high temperatures, poor rate performance and cycle performance, and poor mechanical properties. Sulfide solid electrolytes have corresponding defects: (1) They are easy to react with moisture in the air to generate hydrogen sulfide gas, which affects the stability and safety of the electrolyte; (2) The interface contact between the sulfide electrolyte and the electrode is poor, which easily forms a high interface resistance, resulting in a decrease in the overall performance of the battery; (3) The mechanical strength of the sulfide solid electrolyte is low, and it is easy to crack or break during the cycle, affecting the cycle life of the battery; (4) The electrochemical stability window of the sulfide electrolyte is narrow, and it is easy to decompose at high voltage, which limits its application range. Therefore, providing a new sulfide solid electrolyte is an urgent problem to be solved. Summary of the invention

[0003] The main purpose of the present invention is to provide a micro-nano composite sulfide solid electrolyte and a preparation method and application thereof, so as to overcome the deficiencies of the prior art.

[0004] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes: The embodiment of the present invention provides a micro-nano composite sulfide solid electrolyte, wherein the raw materials of the micro-nano composite sulfide solid electrolyte include: a micron-sized sulfide solid electrolyte, a nano-sized sulfide solid electrolyte and a modified additive; the modified additive includes modified zirconia and / or modified zirconia alumina; the micron-sized sulfide solid electrolyte serves as the structural main body of the micro-nano composite sulfide solid electrolyte, and the nano-sized sulfide solid electrolyte and the modified additive are interspersed and distributed in the micron-sized sulfide solid electrolyte; the micron-sized sulfide solid electrolyte is prepared by a ball milling solid phase synthesis method, and the nano-sized sulfide solid electrolyte is prepared by a liquid phase synthesis method.

[0005] The present invention also provides a method for preparing the aforementioned micro-nano composite sulfide solid electrolyte, which comprises: Micron-sized sulfide solid electrolytes were prepared by ball milling solid phase synthesis method; Nano-scale sulfide solid electrolytes were prepared by lithium naphthalene liquid phase synthesis method; Furthermore, the micron-sized sulfide solid electrolyte and the nano-sized sulfide solid electrolyte are mixed with a modified additive and subjected to ball milling and sintering treatment to obtain a micro-nano composite sulfide solid electrolyte.

[0006] The embodiment of the present invention also provides the use of the aforementioned micro-nano composite sulfide solid electrolyte in preparing a solid electrolyte for a battery or a lithium-ion battery.

[0007] The embodiment of the present invention further provides a lithium-ion battery, which includes: a positive electrode, a negative electrode and a solid electrolyte; wherein the solid electrolyte includes the aforementioned micro-nano composite sulfide solid electrolyte.

[0008] Compared with the prior art, the present invention has the following beneficial effects: (1) The micro-nano composite sulfide solid electrolyte provided by the present invention has the advantages of high safety, high energy density and long cycle life, and can be widely used in the field of battery manufacturing; (2) The addition of the modified additives in the present invention to the sulfide solid electrolyte can significantly improve the air stability, interface performance, mechanical strength and ionic conductivity of the material, and effectively extend the cycle life and safety of the battery by improving the behavior of the interface and grain boundary. Compared with the prior art, the micro-nano composite sulfide solid electrolyte in the present invention has higher commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0010] Figure 1 is a SEM image of the micro-nano composite sulfide solid electrolyte in Example 1 of the present invention; Figure 2 This is a graph of the ionic conductivity of the micro-nano composite sulfide solid electrolyte in Example 1 of the present invention. DETAILED DESCRIPTION

[0011] In view of the defects of the prior art, the inventors of this case have proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution is mainly to obtain a micro-nano composite sulfide solid electrolyte by mixing and sintering a micron-scale sulfide solid electrolyte, a nano-scale sulfide solid electrolyte, and a modified additive (modified Al2O3 and / or modified ZrO2). This method can improve the high temperature performance, rate performance, cycle performance and mechanical properties of the battery.

[0012] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] Specifically, as one aspect of the technical solution of the present invention, the raw materials of a micro-nano composite sulfide solid electrolyte involved therein include: a micron-sized sulfide solid electrolyte, a nano-sized sulfide solid electrolyte and a modified additive; the modified additive includes modified zirconia and / or modified zirconia alumina; the micron-sized sulfide solid electrolyte serves as the structural main body of the micro-nano composite sulfide solid electrolyte, and the nano-sized sulfide solid electrolyte and the modified additive are interspersed and distributed in the micron-sized sulfide solid electrolyte; the micron-sized sulfide solid electrolyte is prepared by a ball milling solid phase synthesis method, and the nano-sized sulfide solid electrolyte is prepared by a liquid phase synthesis method.

[0014] In some preferred embodiments, the mass a of the micron-sized sulfide solid electrolyte and the mass b of the nano-sized sulfide solid electrolyte satisfy: b=(20%~50%)a, and a is greater than 0.

[0015] In some preferred embodiments, the mass ratio of the sum of the micron-sized sulfide solid electrolyte and the nano-sized sulfide solid electrolyte to the modifying additive is 100:1-10.

[0016] Furthermore, the mass ratio of the sum of the micron-sized sulfide solid electrolyte and the nano-sized sulfide solid electrolyte to the modified additive is 100:1-5.

[0017] In some preferred embodiments, the particle size of the micron-sized sulfide solid electrolyte is 1-100 μm.

[0018] In some preferred embodiments, the particle size of the nanoscale sulfide solid electrolyte is 0.2-1 μm.

[0019] In some preferred embodiments, the particle size of the modifying additive is 10-100 nm.

[0020] In some preferred embodiments, the micron-sized sulfide solid electrolyte comprises micron-sized Li 5.5 PS 4.5 Cl 1.5 (LPSCl).

[0021] In some preferred embodiments, the nanoscale sulfide solid electrolyte includes nanoscale Li 5.5 PS 4.5 Cl 1.5(LPSCl).

[0022] In some preferred embodiments, the modified additive is prepared by at least one of a solution method and a ball milling method.

[0023] Furthermore, the method for preparing the modified additive by the solution process specifically comprises: (1) Dissolve 10 g of aluminum nitrate or zirconium oxychloride in 100 mL of deionized water and stir until completely dissolved.

[0024] (2) Add 2 g of citric acid as a complexing agent and stir well.

[0025] (3) Slowly add ammonia water to adjust the pH value of the solution to 7-8 to form a precipitate.

[0026] (4) Heat at 80°C for 1 hour to form a gelatinous precipitate.

[0027] (5) Filter the precipitate, wash it, and dry it at 120°C for 12 hours.

[0028] (6) Finally, the mixture was calcined at 500°C for 4 hours to obtain nano-scale modified alumina and zirconia.

[0029] Furthermore, the method for preparing the modified additive by ball milling specifically comprises: (1) Add 10 g of alumina powder or zirconium dioxide powder and 200 g of ZrO2 balls into a ball mill.

[0030] (2) Add 50 mL of ethanol as solvent.

[0031] (3) Set the ball mill speed to 400 rpm and ball mill for 6 hours.

[0032] (4) After ball milling, the mixture was taken out and dried at 80°C for 12 hours.

[0033] (5) If finer particles are required, the ball milling step can be repeated to obtain nano-scale modified alumina or zirconia.

[0034] When modified Al2O3 is used as the modified additive in the solid electrolysis of micro-nano composite sulfide in the present invention, the modified Al2O3 has high mechanical strength and chemical stability, can significantly improve the mechanical properties and chemical stability of the composite material, and can form a protective coating on the surface of sulfide particles, reduce the decomposition of sulfide electrolyte in the air, and improve its air stability; the modified nano alumina can modify the grain boundary area, reduce the defects and pores of the grain boundary, thereby improving the conductivity of ions at the grain boundary, reducing the loss of total ion conductivity, and forming a composite electrolyte with good conductivity and mechanical strength; the sulfur element in the sulfide electrolyte can form a stable interface structure with the modified Al2O3, reduce the interface resistance, and promote ion conduction.

[0035] When modified ZrO2 is used as an additive in the solid-state electrolysis of micro-nano composite sulfide in the present invention, the modified ZrO2 has excellent mechanical strength and thermal stability, can improve the mechanical properties and high-temperature properties of the composite material, and the modified ZrO2 can form an interface interaction with the sulfide particles to improve the density of the material and reduce the porosity of the electrolyte; at the same time, nano-modified ZrO2 can modify the grain boundary area, reduce the defects and pores of the grain boundary, thereby improving the conductivity of ions at the grain boundary and reducing the loss of total ionic conductivity.

[0036] Another aspect of the embodiments of the present invention further provides a method for preparing the aforementioned micro-nano composite sulfide solid electrolyte, which comprises: Micron-sized sulfide solid electrolytes were prepared by ball milling solid phase synthesis method; Nano-scale sulfide solid electrolytes were prepared by lithium naphthalene liquid phase synthesis method; Furthermore, the micron-scale sulfide solid electrolyte and the nano-scale sulfide solid electrolyte are mixed with a modified additive and subjected to ball milling and sintering treatment to obtain a micro-nano composite sulfide solid electrolyte.

[0037] In some preferred embodiments, the preparation method specifically comprises: Mix lithium, naphthalene and water and react them at a pressure of 1-5 MPa and a temperature of 150° C. for 12-24 hours to obtain a lithium naphthalene solution; Furthermore, the lithium naphthalene solution is reacted with sulfur, and then lithium chloride and phosphorus pentasulfide are added to continue the reaction, and then the reaction is carried out through drying and annealing to obtain a nano-scale sulfide solid electrolyte.

[0038] In some preferred embodiments, the preparation method specifically comprises: mixing lithium sulfide, lithium chloride, and phosphorus pentoxide and ball milling them at a ball milling speed of 350-550 rpm for 8-15 hours to obtain a micron-sized sulfide solid electrolyte.

[0039] In some preferred embodiments, the sintering temperature is 300-500°C.

[0040] In some preferred embodiments, the sintering treatment time is 2 to 5 hours.

[0041] In some more specific embodiments, the method for preparing the micro-nano composite sulfide solid electrolyte comprises the following steps: (1) Prepare raw materials and solvents: Select non-toxic or low-toxic raw materials and solvents, for example, select lithium and naphthalene with a purity of 99.9% as raw materials, and select deionized water as solvent; (2) Optimizing the process conditions of the lithium naphthalene liquid phase synthesis method: lithium and naphthalene were mixed in a molar ratio of 1:1, added to deionized water, and stirred evenly to form a solution. The solution was then placed in an autoclave and reacted at a temperature of 150°C and a pressure of 1.5 MPa for 24 hours to obtain a lithium naphthalene solution. (3) The lithium naphthalene solution reacts with sulfur powder to produce a lithium sulfide solution, lithium chloride and phosphorus pentasulfide are added to generate LPSCl, and the nanoscale sulfide solid electrolyte LPSCl sample is obtained by drying and annealing; (4) ball milling lithium sulfide, lithium chloride and phosphorus pentoxide at a ball milling speed of 500 rpm for 10 hours to obtain a micron-sized sulfide solid electrolyte LPSCl; (5) Designing the mass ratio of nanoparticles and micron particles: mixing the obtained nanoscale sulfide solid electrolyte, micron-scale sulfide solid electrolyte and a third substance (modified Al2O3 and / or modified ZrO2) in a certain mass ratio to obtain a micro-nano composite sulfide solid electrolyte; (6) The final micro-nano composite sulfide solid electrolyte is tested for performance, including ionic conductivity, environmental friendliness, cost, etc., to verify whether the technical means adopted have achieved the expected results. This method can reduce costs while ensuring high ionic conductivity, and also reduce environmental pollution during the synthesis process.

[0042] The present invention overcomes the defects of the prior art by the following means: (1) optimizing the process conditions of the lithium naphthalene liquid phase synthesis method and the ball milling solid phase synthesis method: by adjusting the reaction temperature, pressure, time, solvent type, ball milling speed, time and other parameters, the ion conductivity of the two methods is improved, while the energy consumption and time are reduced; (2) adopting green and environmentally friendly raw materials and solvents: selecting non-toxic or low-toxic raw materials and solvents to reduce environmental pollution during the synthesis process. For example, water is used as a solvent to avoid the use of organic solvents; (3) Design a reasonable mass ratio of nanoparticles and micron particles: Through experimental research, determine the optimal ratio of nanoparticles and micron particles that can both ensure high ionic conductivity and reduce costs. This ratio can be a fixed ratio or a range, so that it can be adjusted according to specific circumstances in actual operation; (4) Combine the lithium naphthalene liquid phase synthesis method and the ball milling solid phase synthesis method: Under large-scale production conditions, these two methods are combined. First, a nanosulfide solid electrolyte with a certain ionic conductivity is prepared by the lithium naphthalene liquid phase synthesis method, and then these nanosulfides are mixed with the micron solid electrolyte to further improve the ionic conductivity of the solid electrolyte and also reduce the cost; (5) Add modified additives (modified Al2O3 and / or modified ZrO2) to the micro-nano sulfide solid electrolyte to further improve the battery's air stability, mechanical properties and critical current density of lithium symmetric batteries.

[0043] The present invention achieves the goal of reducing costs as much as possible while ensuring appropriate ionic conductivity by synthesizing low-cost nano-sulfide solid electrolytes through lithium naphthalene liquid phase and synthesizing high-cost micron solid electrolytes through ball milling solid phase. This method not only avoids the problems of high energy consumption and long time required in traditional methods, but also reduces pollution to the environment. In the present invention, through the ratio between nanoparticles and micron particles, modified additives are further added, which can not only further optimize the electrochemical properties of the solid electrolyte, but also improve the mechanical properties and air stability of the battery. This provides the possibility for large-scale production. The solid electrolyte of the present invention has the advantages of high safety, high energy density and long cycle life, and can be widely used in the field of battery manufacturing. Compared with the solid electrolytes in the prior art, the solid electrolyte of the present invention has significantly improved performance and has higher commercial value.

[0044] Another aspect of the embodiments of the present invention further provides the use of the aforementioned micro-nano composite sulfide solid electrolyte in the preparation of a solid electrolyte for a battery or a lithium-ion battery.

[0045] Another aspect of an embodiment of the present invention further provides a lithium-ion battery, which includes: a positive electrode, a negative electrode and a solid electrolyte; wherein the solid electrolyte includes the aforementioned micro-nano composite sulfide solid electrolyte.

[0046] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments. This embodiment is implemented on the premise of the technical solution of the invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0047] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0048] The preparation methods of the nano-scale sulfide solid electrolyte LPSCl samples and micron-scale sulfide solid electrolyte LPSCl samples in the following examples are as follows: (1) Prepare raw materials and solvents: Select non-toxic or low-toxic raw materials and solvents, for example, select lithium and naphthalene with a purity of 99.9% as raw materials, and select deionized water as solvent; (2) Optimizing the process conditions of the lithium naphthalene liquid phase synthesis method: lithium and naphthalene were mixed in a molar ratio of 1:1, added to deionized water, and stirred evenly to form a solution. The solution was then placed in an autoclave and reacted at a temperature of 150°C and a pressure of 1.5 MPa for 24 hours to obtain a lithium naphthalene solution. (3) The lithium naphthalene solution reacts with sulfur powder to produce a nano lithium sulfide solution, and lithium chloride and phosphorus pentasulfide are further added to generate a nano LPSCl solution, and finally dried and annealed to obtain a nano-scale sulfide solid electrolyte LPSCl sample, wherein the size of the nano LPSCl sample is further controlled by controlling the reaction time for preparing lithium sulfide; (4) Ball milling lithium sulfide, lithium chloride and phosphorus pentoxide at a ball milling speed of 400-500 rpm for 10 hours to obtain a micron-sized sulfide solid electrolyte precursor, and finally annealing to obtain a micron-sized sulfide solid electrolyte LPSCl sample, wherein the size of the micron LPSCl is controlled by controlling the ball milling speed.

[0049] Example 1 1 g of micron-sized sulfide solid electrolyte (100 μm), 0.4 g of nano-sized sulfide solid electrolyte (900 nm) and modified alumina (Al2O3, 1 wt% of the sum of micron-sized sulfide solid electrolyte and nano-sized sulfide solid electrolyte) were mixed in a ball mill for 12 h, and then the mixture was pressed into shape and sintered at 400 °C for 2 h to obtain a micro-nano composite sulfide solid electrolyte. The SEM image of the micro-nano composite sulfide solid electrolyte is shown in FIG. Figure 1 As shown in the figure, the ionic conductivity is Figure 2 shown.

[0050] Lithium symmetric cell assembly: 210 mg of solid electrolyte was pressed into a 13 mm diameter mold at a pressure of 300 MPa for 10 minutes, and then 100 μm thick lithium sheets were placed on both sides of the solid electrolyte sheet. A pressure of 7 MPa was maintained during the test.

[0051] Full cell assembly: The positive electrode material was made of NCM, Ketjen black and LPSCl at a mass ratio of 1:1:3 by ball milling at 240 rpm for 6 hours. The solid electrolyte powder was pressed at 75 MPa for 1 min, and then a certain amount of positive electrode powder was spread on one side of the solid electrolyte sheet and pressed at 300 MPa for 10 min. Finally, lithium foil was spread on the other side of the battery and the pressure of 7 MPa was maintained. The preparation process of NCM (LiNiCoMnO2 (Ni:Co:Mn=8:1:1)) full cell is also similar.

[0052] The prepared micro-nano composite sulfide solid electrolyte was tested for its conductivity at 50°C to 100°C, capacity retention at a rate of 1-5C, compressive strength, etc., as well as the performance of the assembled battery.

[0053] Comparative Example 1 The method is the same as Example 1, except that no modified alumina is added. The specific amount and parameters are shown in Table 1.

[0054] Comparative Example 2 The method is the same as Example 1, except that the nano-scale sulfide solid electrolyte is missing. The specific dosage and parameters are shown in Table 1.

[0055] Comparative Example 3 The method is the same as Example 1, except that the micron-sized sulfide solid electrolyte is missing. The specific dosage and parameters are shown in Table 1.

[0056] Comparative Example 4 The method is the same as Example 1, except that: the dosage of the nano-scale sulfide solid electrolyte and the micro-scale sulfide solid electrolyte. The specific dosage and parameters are shown in Table 1.

[0057] Comparative Example 5 The method is the same as Example 1, except that: the dosage of the nano-scale sulfide solid electrolyte and the micro-scale sulfide solid electrolyte. The specific dosage and parameters are shown in Table 1.

[0058] Comparative Example 6 The method is the same as Example 1, except that: 0.2 g of modified alumina is used. The specific amount and parameters are shown in Table 1.

[0059] Example 2 1 g of micron-sized sulfide solid electrolyte (100 μm), 0.4 g of nano-sized sulfide solid electrolyte (900 nm) and modified alumina (modified Al2O3, 5 wt% of the sum of micron-sized sulfide solid electrolyte and nano-sized sulfide solid electrolyte) were mixed in a ball mill for 12 hours. The mixture was then pressed into shape and sintered at 300°C for 2 hours to obtain a micro-nano composite sulfide solid electrolyte.

[0060] The prepared micro-nano composite sulfide solid electrolyte was tested for its conductivity at 50°C to 100°C, capacity retention at a rate of 1-5C, compressive strength, etc., as well as the performance of the assembled battery.

[0061] Example 3 1 g of micron-sized sulfide solid electrolyte (1 μm), 0.4 g of nano-sized sulfide solid electrolyte (200 nm) and modified zirconium oxide (modified ZrO2, 1 wt% of the sum of micron-sized sulfide solid electrolyte and nano-sized sulfide solid electrolyte) were mixed in a ball mill for 12 hours. The mixture was then pressed into shape and sintered at 500°C for 2 hours to obtain a micro-nano composite sulfide solid electrolyte.

[0062] The prepared micro-nano composite sulfide solid electrolyte was tested for its conductivity at 50°C to 100°C, capacity retention at a rate of 1-5C, compressive strength, etc., as well as the performance of the assembled battery.

[0063] Example 4 1 g of micron-sized sulfide solid electrolyte (50 μm), 0.4 g of nano-sized sulfide solid electrolyte (500 nm) and modified zirconium oxide (modified ZrO2, 10 wt% of the sum of micron-sized sulfide solid electrolyte and nano-sized sulfide solid electrolyte) were mixed in a ball mill for 12 hours. The mixture was then pressed into shape and sintered at 350 ° C for 2 hours to obtain a micro-nano composite sulfide solid electrolyte.

[0064] The prepared micro-nano composite sulfide solid electrolyte was tested for its conductivity at 50°C to 100°C, capacity retention at a rate of 1-5C, compressive strength, etc., as well as the performance of the assembled battery.

[0065] The amounts of raw materials used, the micro-nano composite sulfide solid electrolytes and the battery performance in Examples 1-4 and Comparative Examples 1-6 are shown in Table 1.

[0066] Table 1

[0067] The technical solution provided in the present invention can be widely used in application fields such as new energy battery manufacturing, electric vehicles, and energy storage systems. With the growing global demand for new energy, solid electrolytes, as a new type of electrolyte material, are widely used in the field of battery manufacturing due to their advantages such as high safety, high energy density, and long cycle life. The method of mixing low-cost nano-sulfide solid electrolytes synthesized by liquid phase synthesis of lithium naphthalene and high-cost micron solid electrolytes synthesized by solid phase synthesis of ball milling proposed in the present invention can not only improve the ionic conductivity of the solid electrolyte, but also reduce the cost, and has a great market demand. At the same time, the present invention also studies the ratio between nanoparticles and micron particles, which will help to further optimize the performance of the solid electrolyte and meet higher application requirements.

[0068] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0069] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical deformation made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the protection scope of the present invention.

Claims

1. A micro-nano composite sulfide solid electrolyte, characterized in that: The raw materials of the micro-nano composite sulfide solid electrolyte include: micron-sized sulfide solid electrolyte, nano-sized sulfide solid electrolyte and modified additives; the modified additives include modified zirconia and / or modified zirconia alumina; the micron-sized sulfide solid electrolyte serves as the structural main body of the micro-nano composite sulfide solid electrolyte, and the nano-sized sulfide solid electrolyte and modified additives are interspersed and distributed in the micron-sized sulfide solid electrolyte; the micron-sized sulfide solid electrolyte is prepared by a ball milling solid phase synthesis method, and the nano-sized sulfide solid electrolyte is prepared by a liquid phase synthesis method.

2. The micro-nano composite sulfide solid electrolyte according to claim 1, characterized in that: The mass a of the micron-sized sulfide solid electrolyte and the mass b of the nano-sized sulfide solid electrolyte satisfy: b=(20%-50%)a, and a is greater than 0; And / or, the mass ratio of the sum of the micron-sized sulfide solid electrolyte and the nano-sized sulfide solid electrolyte to the modifying additive is 100:1-10.

3. The micro-nano composite sulfide solid electrolyte according to claim 1, characterized in that: The particle size of the micron-sized sulfide solid electrolyte is 1-100 μm; And / or, the particle size of the nano-scale sulfide solid electrolyte is 0.2-0.9 μm; And / or, the particle size of the modifying additive is 1-100 nm.

4. The micro-nano composite sulfide solid electrolyte according to claim 1, characterized in that: The modified additive is prepared by at least one of a solution method and a ball milling method.

5. The micro-nano composite sulfide solid electrolyte according to claim 1, characterized in that: The micron-sized sulfide solid electrolyte includes micron-sized Li 5.5 PS 4.5 Cl 1.5 ; And / or, the nanoscale sulfide solid electrolyte includes nanoscale Li 5.5 PS 4.5 Cl 1.5 .

6. The method for preparing the micro-nano composite sulfide solid electrolyte according to any one of claims 1 to 5, characterized in that: include: Micron-sized sulfide solid electrolytes were prepared by ball milling solid phase synthesis method; Nano-scale sulfide solid electrolytes were prepared by lithium naphthalene liquid phase synthesis method; Furthermore, the micron-scale sulfide solid electrolyte and the nano-scale sulfide solid electrolyte are mixed with a modified additive and subjected to ball milling and sintering treatment to obtain a micro-nano composite sulfide solid electrolyte.

7. The preparation method according to claim 6, characterized in that: Specifically include: Mix lithium, naphthalene and water and react them at a pressure of 1-5 MPa and a temperature of 150° C. for 12-24 hours to obtain a lithium naphthalene solution; and reacting the lithium naphthalene solution with sulfur, then adding lithium chloride and phosphorus pentasulfide to continue the reaction, and then drying and annealing to obtain a nano-scale sulfide solid electrolyte; And / or, the preparation method specifically comprises: mixing lithium sulfide, lithium chloride and phosphorus pentoxide and ball milling them at a ball milling speed of 350-550 rpm for 8-15 hours to obtain a micron-sized sulfide solid electrolyte.

8. The preparation method according to claim 6, characterized in that: The sintering temperature is 300-500° C. and / or the sintering time is 2-5 hours.

9. Use of the micro-nano composite sulfide solid electrolyte according to any one of claims 1 to 5 in preparing a solid electrolyte for a battery or a lithium ion battery.

10. A lithium ion battery, characterized in that: include: A positive electrode, a negative electrode and a solid electrolyte; wherein the solid electrolyte comprises the micro-nano composite sulfide solid electrolyte according to any one of claims 1 to 5.

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