Tungsten selenide-wn schottky junction loaded carbon material conductive agent, preparation and application thereof

Abstract

The application discloses a kind of tungsten selenide-WN Schottky junction loaded carbon material conductive agent and its preparation method and sulfide full solid battery application.Preparation method includes steps: (1) in the condition that emulsifier and co-emulsifier exist, with dopamine hydrochloride as polymerization monomer, first reaction is carried out in first solvent, and dopamine microspheres are obtained;(2) dopamine microspheres and urea, tungsten precursor are reacted in second solvent to obtain polymer precursor;(3) under inert atmosphere, the third reaction is carried out to polymer precursor and selenium powder, and WSe2-WN Schottky junction loaded carbon material conductive agent is obtained.

Description

Technical Field

[0001] This invention relates to the field of sulfide all-solid-state batteries, specifically to a tungsten selenide (WSe2)-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent, its preparation method, and its application in sulfide all-solid-state batteries. Background Technology

[0002] Over the past decade, the demand for next-generation rechargeable batteries with high energy and power density has increased. Significant efforts have been devoted to developing secondary batteries for electric vehicles in an effort to reduce greenhouse gas emissions. However, electric vehicles still face challenges such as short driving range per charge and long charging times, stemming from the energy and power density limitations of conventional lithium-ion batteries. Currently, one of the most promising solutions is the development of sulfide solid-state batteries.

[0003] However, chemical / electrochemical side reactions (occurring at the interface between the sulfide electrolyte and the conductive material) exist in the composite cathode of sulfide solid-state batteries, thus degrading battery performance. Currently, there are no reported studies on the modification of carbon materials; most research on carbon materials focuses on their morphology, particle size, specific surface area, and the coating of sulfide electrolyte materials. Unfortunately, these methods still cannot effectively suppress the chemical / electrochemical side reactions at the interface to improve interfacial stability.

[0004] Therefore, it is extremely important to develop a conductive agent that can be applied to sulfide all-solid-state batteries.

[0005] The following existing technologies were found through a search: Patent specification CN120497287A discloses a positive electrode sheet, its preparation method, and a sulfide all-solid-state battery. The positive electrode sheet includes a positive current collector and a positive electrode material layer disposed on the surface of the current collector. The positive electrode material layer includes a modified positive electrode active material, an antioxidant, a sulfide electrolyte material, a conductive agent, and a positive electrode binder. The conductive agent includes, but is not limited to, one or more of conductive carbon black, conductive graphite, acetylene black, Ketjen black, vapor-grown carbon fiber (VGCF), carbon nanotubes, and graphene.

[0006] Patent specification CN120749167A discloses a MoS2 / MoN / C conductive agent, its preparation method, and its application in sulfide all-solid-state batteries. This patented technology first prepares formaldehyde-melamine polymer microspheres, then impregnates these microspheres to adsorb molybdenum salt and ammonia, obtaining a polymer precursor. Subsequently, the MoS2 / MoN / C conductive agent is obtained through the pyrolysis reaction of the polymer precursor and thiourea. Compared to traditional conductive agents, the MoS2 / MoN / C conductive agent prepared by this patented technology does not induce chemical / electrochemical side reactions in the sulfide solid-state electrolyte cathode material, exhibits excellent electronic conductivity and ion mobility, and demonstrates excellent stability, which can promote the development of sulfide electrolyte all-solid-state batteries. However, the conductive agent prepared by this patented technology has a particle size of 0.8-6.5 μm, making it difficult to form an excellent particle size distribution with the active material (typically 10 μm particle size) and sulfide electrolyte (typically 5 μm particle size) in the composite cathode. In existing research, effectively reducing the particle size of carbon materials to fill pores and construct an excellent electronic conductivity network in composite cathodes is of great significance for improving the performance of sulfide solid-state batteries. Furthermore, the formation of the MoS2 / MoN heterojunction primarily involves SN exchange at the interface, which is beneficial for creating defects and enhancing electron transport capabilities within the heterostructure. However, this also weakens the high ionic conductivity inherent in MoS2 itself.

[0007] This invention aims to construct nanoscale carbon framework particles and load a van der Waals force-dominated heterostructure on their surface, thereby constructing an excellent ionic / electronic conductive network on their surface. Summary of the Invention

[0008] This invention provides a WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent, its preparation method, and its application in sulfide all-solid-state batteries, which can better solve the problems of interfacial chemistry / side reactions in existing sulfide all-solid-state batteries.

[0009] The specific technical solution is as follows: In a first aspect, the present invention provides a method for preparing a conductive agent of WSe2-WN Schottky junction supported carbon material (WSe2-WN / C), comprising the steps of: (1) In the presence of emulsifier and co-emulsifier, dopamine hydrochloride is used as the polymerization monomer and the first reaction is carried out in the first solvent to obtain dopamine microspheres; (2) The dopamine microspheres are reacted with urea and tungsten precursor in a second solvent to obtain a polymer precursor; (3) Under an inert atmosphere, the polymer precursor and selenium powder are subjected to a third reaction to obtain WSe2-WN Schottky junction supported carbon material conductive agent.

[0010] In step (1), dopamine hydrochloride can undergo a polymerization reaction to generate nanopolymer microspheres (dopamine microspheres) with high specific surface area and uniform particle size distribution. The structure of dopamine microspheres is beneficial for the second reaction of tungsten precursor and also facilitates the introduction of nitrogen element to improve the electronic conductivity of the material.

[0011] Furthermore, in step (1), the dopamine microspheres are nanoscale.

[0012] In some preferred embodiments, step (1) specifically includes: adding an emulsifier, a co-emulsifier, and dopamine hydrochloride sequentially to a first solvent to carry out a first reaction; after the first reaction is completed, the solid is washed and dried to obtain dopamine microspheres. Further, after adding the emulsifier and co-emulsifier, it is preferable to stir at room temperature for a period of time (e.g., 20-60 min) before adding dopamine hydrochloride.

[0013] Furthermore, the first solvent is a water-in-oil (W / O) emulsion, and dopamine hydrochloride will undergo a polymerization reaction at the interface of the water-in-oil emulsion to eventually form nanopolymer microspheres.

[0014] In some preferred embodiments, in step (1), the first solvent comprises continuous phase oil and deionized water. Further, the continuous phase oil comprises at least one of white oil and kerosene.

[0015] In some preferred embodiments, the volume ratio of continuous phase oil to deionized water is 6-12:1, more preferably 6-10:1, such as 8:1, 9:1, etc. If the volume ratio of continuous phase oil to deionized water in the first solvent is too low, for example, if the volume ratio of continuous phase oil to deionized water is 1:1, the oil-water ratio is too low, making it difficult to form a water-in-oil emulsion. However, by limiting the volume ratio of continuous phase oil to deionized water in the first solvent to the above-mentioned range, a water-in-oil emulsion can be formed, with better results.

[0016] In some preferred embodiments, the ratio of dopamine hydrochloride to the first solvent is 0.01-0.1 mol: 100 mL, and more preferably 0.05-0.1 mol: 100 mL.

[0017] In some preferred embodiments, in step (1), the emulsifier includes the Span series, or a blend of the Span series and the Tween series, or a blend of the Span series and the OP series. Further, in the blend of the Span series and the Tween series, the mass ratio of the Span series to the Tween series is preferably (2-6):1, for example, 3:1, 4:1, 5:1, etc. Further, in the blend of the Span series and the OP series, the mass ratio of the Span series to the OP series is preferably (2-6):1, for example, 3:1, 4:1, 5:1, etc.

[0018] In some preferred embodiments, the Span series includes one or more of Span-85, Span-80, Span-65, Span-60, Span-40, and Span-20.

[0019] In some preferred embodiments, the Tween series includes one or more of Tween-20, Tween-40, Tween-60, and Tween-80.

[0020] In some preferred embodiments, the OP series includes one or more of OP-4, OP-7, OP-9, OP-10, OP-13, OP-15, OP-20, OP-30, OP-40, and OP-50.

[0021] Emulsifiers preferably include a combination of Span and Tween series, or a combination of Span and OP series, which helps to improve the stability of the oil-water interface.

[0022] In some preferred embodiments, in step (1), the ratio of emulsifier to first solvent is 5-15g:100mL, and more preferably 8-15g:100mL.

[0023] In some preferred embodiments, in step (1), the co-emulsifier includes one or more of n-butanol, n-hexanol, and isobutanol. In this invention, the introduction of the co-emulsifier is beneficial for reducing the diameter of droplets in the water-in-oil emulsion and for the formation of nanopolymer microspheres.

[0024] In some preferred embodiments, in step (1), the volume ratio of the co-emulsifier to the first solvent is 2-10:100.

[0025] In some preferred embodiments, in step (1), the temperature of the first reaction is 40-60°C, for example 50°C.

[0026] In some preferred embodiments, the time for the first reaction in step (1) is 6-12 hours, more preferably 8-10 hours, such as 9 hours.

[0027] Step (2) The second reaction is the impregnation process of dopamine microspheres.

[0028] In some preferred embodiments, step (2) specifically includes: dispersing dopamine microspheres in a second solvent containing urea and a tungsten precursor, allowing the mixture to stand to undergo a second reaction, and then freeze-drying the mixture after the second reaction is complete to obtain the polymer precursor. Further, the freeze-drying is carried out at -60°C and 12 Pa. Further, the freeze-drying time is 12-24 h, for example, 18 h.

[0029] In some preferred embodiments, in step (2), the second solvent includes deionized water.

[0030] In some preferred embodiments, in step (2), the ratio of dopamine microspheres to the second solvent is 5-20 g: 100 mL, preferably 8-15 g: 100 mL, for example 12 g: 100 mL.

[0031] In step (2), urea is used to further increase the content of nitrogen, which is beneficial to the formation of tungsten nitride.

[0032] In some preferred embodiments, in step (2), the ratio of urea to the second solvent is 5-20 g: 100 mL, such as 6 g: 100 mL, 7 g: 100 mL, 9 g: 100 mL, 16 g: 100 mL, etc.

[0033] In some preferred embodiments, in step (2), the tungsten precursor includes at least one of ammonium tungstate and tungsten oxalate.

[0034] In some preferred embodiments, in step (2), the tungsten precursor is added in solution form. Further: the concentration of tungsten precursor in the tungsten precursor solution is preferably 0.01-0.1 mol / L, more preferably 0.03-0.08 mol / L, for example 0.05 mol / L, etc.; the volume ratio of the tungsten precursor solution and the second solvent is preferably 30-60:100, for example 35:100, 40:100, 45:100, 50:100, 60:100, etc., more preferably 45-60:100.

[0035] In some preferred embodiments, in step (2), the temperature of the second reaction is 25-35°C, for example 30°C.

[0036] In some preferred embodiments, the second reaction time in step (2) is 6-24 hours, such as 12 hours, 14 hours, 20 hours, 22 hours, etc.

[0037] In step (3), the polymer precursor undergoes pyrolysis, primarily resulting in the loss of H and O elements. Tungsten species react to form WN under sufficient nitrogen source conditions. Furthermore, tungsten species react with selenium powder at the interface to form WSe2. Additionally, under the third reaction conditions, a van der Waals force-dominated WSe2-WN heterostructure forms on the carbon material surface, thereby constructing ion / electron migration pathways on the carbon material surface.

[0038] In this invention, an inert atmosphere refers to a gaseous atmosphere that does not participate in the reaction.

[0039] In some preferred embodiments, in step (3), the inert atmosphere is an Ar atmosphere.

[0040] In step (3), selenium powder is used to form a two-dimensional structure of tungsten selenide on the surface of the material to improve the ion mobility of the material.

[0041] In some preferred embodiments, in step (3), the mass ratio of selenium powder to polymer precursor is 5-50:100, such as 20:100, 29:100, 30:100, 40:100, 50:100, etc., and more preferably 30-50:100.

[0042] In some preferred embodiments, in step (3), the temperature of the third reaction is 600-1000°C, more preferably 800-1000°C, such as 900°C.

[0043] In some preferred embodiments, the time for the third reaction in step (3) is 5-10 hours, more preferably 8-10 hours, such as 9 hours.

[0044] In a second aspect, the present invention provides a conductive agent for WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) prepared by the preparation method described in the first aspect.

[0045] Furthermore, the particle size distribution of the conductive agent in the WSe2-WN Schottky junction supported carbon material exhibits a single peak.

[0046] Furthermore, the average particle size of the WSe2-WN Schottky junction supported carbon material conductive agent is 80-260 nm, for example 230 nm, and preferably 80-150 nm.

[0047] Thirdly, the present invention provides the application of the WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent described in the second aspect in sulfide all-solid-state batteries.

[0048] Fourthly, the present invention provides a positive electrode material comprising the WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent, sulfide electrolyte, and active material as described in the second aspect.

[0049] Fifthly, the present invention provides a sulfide all-solid-state battery, comprising a positive electrode, a negative electrode and a sulfide solid electrolyte, wherein the positive electrode comprises the positive electrode material described in the fourth aspect.

[0050] Compared with the prior art, the beneficial effects of this invention are as follows: 1. Compared with traditional conductive agents, the WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent of the present invention will not induce chemical / electrochemical side reactions in the sulfide solid electrolyte cathode material.

[0051] 2. Compared with traditional conductive agents, the WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) of this invention has excellent electronic conductivity and ion mobility.

[0052] 3. Compared with traditional conductive agents, the WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent of this invention has excellent stability, which can promote the commercial development of sulfide electrolyte all-solid-state batteries. Detailed Implementation

[0053] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0054] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0055] Example 1: The preparation method of conductive agent for WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) includes the following steps: (1) In a three-necked round-bottom flask equipped with a stir bar, thermometer, and nitrogen inlet tube, 20 mL of deionized water, 27.5 g of Span-60, 5.5 g of Tween-20, and 10 mL of n-butanol were added sequentially to 200 mL of white oil. The mixture was stirred at room temperature for 60 min, then 0.2 mol of dopamine hydrochloride was added, and the mixture was heated to 60 °C and reacted for 10 h. After the reaction was complete, the solid was centrifuged, washed, and vacuum dried to obtain dopamine microspheres.

[0056] (2) Add 15g of dopamine microspheres, 10g of urea and 60mL of 0.08mol / L ammonium tungstate solution to 100mL of deionized water, let stand at 35℃ for 24h, and then freeze dry (-60℃, 12Pa) for 24h to finally obtain the polymer precursor.

[0057] (3) In a tube furnace filled with Ar atmosphere, 50g of polymer precursor and 25g of selenium powder were mixed evenly, and the temperature was raised to 1000℃ for carbonization for 10h. Finally, WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent was obtained, named conductive agent-1. The particle size distribution was unimodal, and the average particle size (D50, the same below) was 87.5 nm.

[0058] Example 2: The preparation method of conductive agent for WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) includes the following steps: (1) In a three-necked round-bottom flask equipped with a stirrer, thermometer, and nitrogen inlet tube, 20 mL of deionized water, 12.3 g of Span-85, 2.1 g of OP-10, and 5 mL of n-hexanol were added sequentially to 160 mL of kerosene. The mixture was stirred at room temperature for 20 min, and then 0.08 mol of dopamine hydrochloride was added. The mixture was heated to 40 °C and reacted for 8 h. After the reaction was completed, the solid was centrifuged, washed, and vacuum dried to obtain dopamine microspheres.

[0059] (2) 16g of dopamine microspheres, 10g of urea and 90mL of 0.03mol / L tungsten oxalate solution were added to 200mL of deionized water, and the mixture was allowed to stand at 25℃ for 6h. Then it was freeze-dried (-60℃, 12Pa) for 12h to finally obtain the polymer precursor.

[0060] (3) In a tube furnace filled with Ar atmosphere, 50g of polymer precursor and 15g of selenium powder were mixed evenly, and the temperature was raised to 800℃ for carbonization for 8h. Finally, WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent was obtained, named conductive agent-2, with a single peak in particle size distribution and an average particle size of 108.8 nm.

[0061] Example 3: The preparation method of conductive agent for WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) includes the following steps: (1) In a three-necked round-bottom flask equipped with a stirring rod, thermometer, and nitrogen inlet tube, 20 mL of deionized water, 8.0 g of Span-60, 2.0 g of OP-40, and 8 mL of isobutanol were added sequentially to 180 mL of kerosene. The mixture was stirred at room temperature for 40 min, then 0.13 mol of dopamine hydrochloride was added, and the mixture was heated to 50 °C and reacted for 9 h. After the reaction was complete, the solid was centrifuged, washed, and vacuum dried to obtain dopamine microspheres.

[0062] (2) 24g of dopamine microspheres, 12g of urea and 100mL of 0.05mol / L ammonium tungstate solution were added to 200mL of deionized water, and the mixture was allowed to stand at 30℃ for 12h. Then, it was freeze-dried (-60℃, 12Pa) for 18h to finally obtain the polymer precursor.

[0063] (3) In a tube furnace filled with Ar atmosphere, 100g of polymer precursor and 40g of selenium powder were mixed evenly, and the temperature was raised to 900℃ for carbonization for 9h. Finally, WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent was obtained, named conductive agent-3, with a single peak in particle size distribution and an average particle size of 143.1 nm.

[0064] Example 4: The preparation method of conductive agent for WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) includes the following steps: (1) In a three-necked round-bottom flask equipped with a stir bar, thermometer, and nitrogen inlet tube, 10 mL of deionized water, 4.4 g of Span65, 2.2 g of OP-50, and 6 mL of n-butanol were added sequentially to 120 mL of white oil. The mixture was stirred at room temperature for 60 min, and then 0.013 mol of dopamine hydrochloride was added. The mixture was heated to 60 °C and reacted for 6 h. After the reaction was complete, the solid was centrifuged, washed, and vacuum dried to obtain dopamine microspheres.

[0065] (2) Add 5g of dopamine microspheres, 7g of urea and 30mL of 0.01mol / L tungsten oxalate solution to 100mL of deionized water, let stand at 25℃ for 24h, and then freeze dry (-60℃, 12Pa) for 20h to finally obtain the polymer precursor.

[0066] (3) In a tube furnace filled with Ar atmosphere, 50g of polymer precursor and 2.5g of selenium powder were mixed evenly, and the temperature was raised to 600℃ for carbonization for 5h. Finally, WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent was obtained, named conductive agent-4, with a single peak in particle size distribution and an average particle size of 172.4 nm.

[0067] Example 5: The preparation method of conductive agent for WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) includes the following steps: (1) In a three-necked round-bottom flask equipped with a stirring rod, thermometer, and nitrogen inlet tube, 20 mL of deionized water, 7.35 g of Span-20, 2.45 g of OP-10, and 8 mL of isobutanol were added sequentially to 120 mL of kerosene. The mixture was stirred at room temperature for 30 min, and then 0.075 mol of dopamine hydrochloride was added. The mixture was heated to 40 °C and reacted for 12 h. After the reaction was complete, the solid was centrifuged, washed, and vacuum dried to obtain dopamine microspheres.

[0068] (2) Add 20g of dopamine microspheres, 16g of urea and 40mL of 0.1mol / L ammonium tungstate solution to 100mL of deionized water, let stand at 35℃ for 6h, and then freeze dry (-60℃, 12Pa) for 14h to finally obtain the polymer precursor.

[0069] (3) In a tube furnace filled with Ar atmosphere, 50g of polymer precursor and 14.5g of selenium powder were mixed evenly, and the temperature was raised to 700℃ for carbonization for 7h. Finally, WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent was obtained, named conductive agent-5, with a single peak in particle size distribution and an average particle size of 192.3 nm.

[0070] Example 6: The preparation method of conductive agent for WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) includes the following steps: (1) In a three-necked round-bottom flask equipped with a stirring rod, thermometer, and nitrogen inlet tube, 20 mL of deionized water, 6.72 g of Span-20, 1.68 g of Tween-870, and 7 mL of n-hexanol were added sequentially to 120 mL of kerosene. The mixture was stirred at room temperature for 45 min, and then 0.045 mol of dopamine hydrochloride was added. The mixture was heated to 50 °C and reacted for 7 h. After the reaction was completed, the solid was centrifuged, washed, and vacuum dried to obtain dopamine microspheres.

[0071] (2) 7g of dopamine microspheres, 9g of urea and 35mL of 0.02mol / L tungsten oxalate solution were added to 100mL of deionized water. The mixture was allowed to stand at 33℃ for 16h and then freeze-dried (-60℃, 12Pa) for 22h to finally obtain the polymer precursor.

[0072] (3) In a tube furnace filled with Ar atmosphere, 50g of polymer precursor and 10g of selenium powder were mixed evenly, and the temperature was raised to 650℃ for carbonization for 6h. Finally, WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent was obtained, named conductive agent-6, with a single peak in particle size distribution and an average particle size of 228.0 nm.

[0073] Comparative Example 1: The only difference from Example 1 is that 27.5g of Span-60 is not added in step (1), and all other steps are the same. Conductive agent D-1 is obtained with a single-peak particle size distribution and an average particle size of 1.23μm.

[0074] Comparative Example 2: The only difference from Example 1 is that 5.5g of Tween20 is not added in step (1), and all other steps are the same. The conductive agent D-2 is obtained with a single peak in particle size distribution and an average particle size of 3.12μm.

[0075] Comparative Example 3: The only difference from Example 1 is that 10 mL of n-butanol is not added in step (1), and all other steps are the same. Conductive agent D-3 is obtained with a single peak in particle size distribution and an average particle size of 5.21 μm.

[0076] Comparative Example 4: The only difference from Example 1 is that dopamine hydrochloride is not added in step (1), and the rest are the same. The conductive agent D-4 is obtained with a multi-peaked particle size distribution and an average particle size of 4.34 μm.

[0077] Comparative Example 5: The only difference from Example 1 is that the concentration of ammonium tungstate solution in step (2) is changed to 0.001 mol / L. All other steps are the same, and conductive agent D-5 is obtained with a single-peak particle size distribution and an average particle size of 0.32 μm.

[0078] Comparative Example 6: The only difference from Example 1 is that 25g of selenium powder is not added in step (3), and the rest are the same. Conductive agent D-6 is obtained with a single peak in particle size distribution and an average particle size of 0.48μm.

[0079] Comparative Example 7: The only difference from Example 1 is that in step (3), 1000℃ is changed to 100℃. All other conditions are the same. Conductive agent D-7 is obtained with a multi-peaked particle size distribution and an average particle size of 11.23μm.

[0080] Comparative Example 8: The only difference from Example 1 is that in step (3), carbonization at 1000℃ for 10 hours is changed to carbonization at 1000℃ for 1 hour. All other steps are the same, and conductive agent D-8 is obtained with a multi-peaked particle size distribution and an average particle size of 9.52 μm.

[0081] The conductive agent of this invention has a Schottky junction heterostructure, wherein WSe2-WN are connected by van der Waals forces. WSe2 provides excellent ionic conductivity, while WN provides excellent electronic conductivity. Furthermore, this invention uses dopamine microspheres as a polymer precursor, reducing the particle size of the resulting carbon substrate to approximately 100 nm. This facilitates the formation of excellent particle size distribution with other components in the composite cathode, thus constructing a superior electronic / ionic conductivity network within the composite cathode.

[0082] Test example: Assembly method of sulfide all-solid-state batteries: (1) Preparation of positive electrode material: The conductive agent, sulfide electrolyte LPSC (lithium phosphorus sulfide) and active material LCO (lithium cobalt oxide) are placed in an agate mortar in a weight ratio of 8:22:70 and mixed evenly for 50 min to obtain a composite positive electrode.

[0083] (2) Assembly of sulfide all-solid-state battery: 100 mg of sulfide electrolyte LPSC was added to a mold with a diameter of 10 mm and pressed at 50 MPa for 10 min to form a solid electrolyte layer. Then, 10 mg of composite positive electrode was evenly spread on one side of the electrolyte layer and pressed at 200 MPa for 10 min to make it in close contact with the solid electrolyte. Finally, 16 mg of Li / In negative electrode (lithium indium negative electrode) was evenly spread on the other side of the solid electrolyte and pressed at 30 MPa for 1 min to complete the assembly of the solid-state battery.

[0084] The first-cycle coulombic efficiency and first-cycle discharge capacity (0.1C) of solid-state batteries with different conductive agents were tested. The test data are shown in Table 1.

[0085] Table 1 As shown in Table 1, the solid-state battery containing WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent exhibits higher first-cycle coulombic efficiency and discharge capacity, which are much higher than those of commercial carbon nanotube conductive agents and the conductive agents obtained in the comparative example.

[0086] Further tests were conducted on the discharge capacity and capacity retention of solid-state batteries with different conductive agents after 100 cycles at a current density of 0.1C. The results are shown in Table 2.

[0087] Table 2 As shown in Table 2, the solid-state battery containing WSe2-WN Schottky junction supported carbon material (WSe2-WN / C) conductive agent exhibits a high capacity retention rate, which is much higher than that of commercial carbon nanotube conductive agents and the conductive agents obtained in the comparative example.

[0088] Further testing was conducted on the EIS impedance data of solid-state batteries with different conductive agents before and after 100 cycles at a current density of 0.1C. The results are shown in Table 3.

[0089] Table 3 As shown in Table 3, the interfacial impedance of carbon nanotubes and the comparative sample changed significantly after cycling. This is believed to be due to the appearance of sulfites leading to interfacial instability, which in turn inhibits electron migration and thus deteriorates battery performance.

[0090] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for preparing a WSe2-WN Schottky junction loaded with a carbon material conductive agent, characterized in that, Including the following steps: (1) In the presence of emulsifier and co-emulsifier, dopamine hydrochloride is used as the polymerization monomer and the first reaction is carried out in the first solvent to obtain dopamine microspheres; the first solvent is a water-in-oil emulsion. (2) The dopamine microspheres are reacted with urea and tungsten precursor in a second solvent to obtain a polymer precursor; (3) Under an inert atmosphere, the polymer precursor and selenium powder undergo a third reaction, and the polymer precursor undergoes pyrolysis to obtain WSe2-WN Schottky junction supported carbon material conductive agent; the inert atmosphere refers to a gaseous atmosphere that does not participate in the reaction.

2. The production method according to claim 1, characterized by, In step (1): Dopamine microspheres are nanoscale; The ratio of dopamine hydrochloride to the first solvent is 0.01-0.1 mol: 100 mL; The temperature of the first reaction is 40-60℃; The time for the first reaction is 6-12 hours.

3. The preparation method according to claim 1, characterized in that, In step (2): The ratio of dopamine microspheres to the second solvent is 5-20 g: 100 mL; The ratio of urea to the second solvent is 5-20g:100mL; Tungsten precursors include at least one of ammonium tungstate and tungsten oxalate; The tungsten precursor is added in solution form; the concentration of tungsten precursor in the tungsten precursor solution is 0.01-0.1 mol / L; the volume ratio of the tungsten precursor solution to the second solvent is 30-60:

100.

4. The preparation method according to claim 1, characterized in that, In step (3): The inert atmosphere is an Ar atmosphere; The mass ratio of selenium powder to polymer precursor is 5-50:100; The temperature for the third reaction is 600-1000℃; The third reaction takes 5-10 hours.

5. The WSe2-WN Schottky junction supported carbon material conductive agent is prepared by the preparation method according to any one of claims 1-4.

6. The WSe2-WN Schottky junction supported carbon material conductive agent according to claim 5, characterized in that, The conductive agent in the WSe2-WN Schottky junction supported carbon material exhibits a single-peak particle size distribution with an average particle size of 80-260 nm.

7. The application of the WSe2-WN Schottky junction supported carbon material conductive agent according to claim 5 or 6 in sulfide all-solid-state batteries.

8. A positive electrode material, characterized in that, It includes the WSe2-WN Schottky junction supported carbon material conductive agent, sulfide electrolyte, and active material as described in claim 5 or 6.

9. A sulfide all-solid-state battery, comprising a positive electrode, a negative electrode, and a sulfide solid electrolyte, characterized in that, The positive electrode comprises the positive electrode material as described in claim 8.

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