Preparation method and application of lithium-sulfur battery positive electrode catalytic material

Abstract

The application discloses a preparation method and application of a lithium-sulfur battery positive electrode catalytic material, a three-dimensional porous graphene carrier three-dimensional connected hierarchical pore structure is used to form strong physical confinement, and migration and diffusion of LiPSs are inhibited from a spatial dimension; In2O3 and LiNbO3 are jointly loaded in a graphene conductive network, a piezoelectric effect is generated in-situ by stress induction in a charge and discharge cycle, a dynamic local microelectric field is constructed, migration behavior of LiPSs is directionally controlled, interaction between LiPSs and In2O3 active sites is strengthened, a LiPSs conversion reaction energy barrier to an insoluble discharge product Li2S is reduced, efficient adsorption and rapid complete conversion of LiPSs are realized, and the positive electrode catalytic system constructed by the physical confinement, selective catalysis and piezoelectric microelectric field regulation can inhibit LiPSs shuttling, accelerate reaction kinetics and relieve volume expansion from the root, and the cycle stability and rate performance of the lithium-sulfur battery are significantly improved.

Description

Technical Field

[0002] This invention belongs to the field of lithium-sulfur battery cathode material technology, specifically relating to a method for preparing and applying a lithium-sulfur battery cathode catalytic material. Background Technology

[0004] With a theoretical specific capacity of 1675 mAh / g and a theoretical energy density of 2600 Wh / kg, lithium-sulfur batteries have become a core candidate for the next generation of high-energy-density energy storage technology. However, their commercialization process is hampered by three major technical challenges: the extremely poor intrinsic conductivity of elemental sulfur (S) and the discharge end product lithium sulfide (Li2S); the sulfur cathode volume expansion rate exceeding 80% during charge-discharge cycles; and the shuttle effect caused by the intermediate products of charge-discharge lithium polysulfides (LiPSs). Among these, the shuttle effect of LiPSs is the core cause of the rapid capacity decay and poor cycle stability of lithium-sulfur batteries.

[0005] Currently, mainstream solutions to the LiPS shuttle effect focus on the physical confinement and chemisorption mechanisms of sulfur-based supports. Carbon-based supports, with their well-developed porous structure, can mitigate the loss of active materials through physical confinement; however, the interaction between the nonpolar interface of carbon-based supports and polar LiPSs is weak, making it difficult to effectively immobilize LiPSs. While polar compounds (such as metal oxides and sulfides) can strongly anchor LiPSs through chemical bonding, their poor structural stability during charge-discharge cycles makes them prone to phase transitions or dissolution, leading to decreased battery cycle stability. Although these methods can delay the diffusion and loss of LiPSs to some extent, they do not address the root cause of the problem.

[0006] The essence of the LiPS shuttle effect lies not only in its dissolution and diffusion in the electrolyte, but also in the sluggish redox conversion kinetics between LiPS and Li₂S₂ / Li₂S. This kinetic inertia prevents LiPS from being converted into insulating products in a timely manner, leading to their continued migration and diffusion in the electrolyte, creating a vicious cycle. Therefore, constructing a dynamic equilibrium system of "adsorption-catalytic conversion" and introducing functional materials with both appropriate LiPS adsorption capacity and high-efficiency catalytic conversion activity is the core path to fundamentally overcome the shuttle effect. The core value of the catalyst lies not only in its ability to anchor LiPS through chemical adsorption, but also in its ability to lower the energy barrier of the redox reaction, accelerate the reduction reaction of LiPS to Li₂S₂ / Li₂S, and achieve the oxidation reaction of Li₂S to LiPS, enabling LiPS to be converted into insoluble products in a timely manner, fundamentally curbing the shuttle effect, and simultaneously improving the electrode reaction rate and the utilization rate of active materials.

[0007] Existing technology, patent document CN202310577015.3 discloses a highly active cathode material catalyst for lithium-sulfur batteries and its preparation method. The catalyst comprises a sheet-like nitrogen-doped carbon-based support and uniformly embedded molybdenum metal nanoclusters on the support surface. The molybdenum metal nanoclusters are 1-10 nm in size and have a mass ratio of 10-20 wt% on the support. After melting sulfur, they serve as the cathode material for lithium-sulfur batteries. The catalyst uses cyanamide compounds and organometallic molybdenum salts as raw materials, or further adds defective carbon materials. Through thorough physical mixing, it is directly carbonized in a tube furnace under an inert atmosphere. The high specific surface area sheet-like nitrogen-doped carbon conductive material with uniformly distributed molybdenum metal nanoclusters physically adsorbs and chemically catalyzes polysulfides formed during the charge-discharge process of the lithium-sulfur battery cathode, capturing polysulfides, solving the shuttle effect during charge-discharge, and ultimately improving the electrochemical performance of the electrode material. Patent document CN202210296008.1 discloses a lithium-sulfur battery cathode catalytic material and its preparation method and application. The lithium-sulfur battery cathode catalytic material is a composite material formed by in-situ growth of phosphorus-doped transition metal selenide on conductive carbon material. The specific preparation process is to use an in-situ growth method to pre-treat the carbon material and then immerse it in a solution containing transition metal salt. After reacting with the solution, the solid product is separated. Then, the solid product is selenized and doped at high temperature to finally obtain a carbon composite material embedded with phosphorus-doped transition metal selenide. Patent document CN202311467501.6 discloses an indium-based oxide catalyst, a modified coating, a modified separator, and a lithium-sulfur battery. The preparation process of the indium-based oxide catalyst involves adding indium nitrate, isophthalic acid, DMF, acetonitrile, imidazole, and nitric acid to a reaction vessel, reacting at 80°C for 12 h, then heating to 100°C for 24 h, washing with DMF and anhydrous ethanol respectively, and vacuum drying for 12 h to obtain an In-MOF precursor. The In-MOF precursor is then maintained under a nitrogen atmosphere at 200-600°C for 4 h, and naturally cooled to room temperature to obtain the indium-based oxide catalyst. The prepared indium-based oxide catalyst largely retains the corresponding three-dimensional hierarchical porous framework structure of the original MOF. The indium-based oxide catalyst contains highly dispersed metal active sites, effectively reducing the aggregation of metal oxides or elemental metals, thus exhibiting superior catalytic activity. The organic ligand isophthalic acid undergoes pyrolysis under an inert atmosphere to generate a large amount of carbon material, greatly improving the conductivity of the indium-based oxide catalyst. However, the technical solutions in the aforementioned patent documents did not fundamentally solve the shuttle effect of LiPSs.

[0008] This invention introduces a catalytic material that combines high catalytic activity with low cost, thereby significantly reducing the redox reaction energy barrier and accelerating conversion kinetics while appropriately anchoring LiPSs. This fundamentally curbs the shuttle effect, providing core technological support for the commercialization breakthrough of lithium-sulfur batteries. Currently, there are no related reports in this area. Summary of the Invention

[0010] The technical problem solved by this invention is to overcome the shortcomings of the prior art and to provide a method for preparing and applying a lithium-sulfur battery cathode catalytic material. Starting from material structure design and multifunctional coupling mechanisms, this invention constructs a lithium-sulfur battery composite catalytic system integrating "physical confinement - local micro-electric field regulation - catalytic accelerated conversion". First, a three-dimensional porous graphene support is prepared using the sacrificial template method. Its three-dimensional interconnected hierarchical pore structure forms a strong physical confinement, which inhibits the migration and diffusion of LiPSs from a spatial dimension. Then, the catalyst (In2O3) and the ferroelectric piezoelectric material lithium niobate (LiNbO3) are co-loaded in the graphene conductive network. By utilizing the piezoelectric effect induced by stress in LiNbO3 during charge-discharge cycles, a dynamic local micro-electric field is constructed in situ. The migration behavior of LiPSs is directionally regulated by the electric field force, and the interaction between LiPSs and the catalytic active sites of In2O3 is strengthened. This significantly reduces the reaction energy barrier for the conversion of LiPSs into the insoluble discharge product Li2S, achieving efficient adsorption and rapid complete conversion of LiPSs. This fundamentally solves the shuttle effect and significantly improves the rate performance and long-cycle stability of lithium-sulfur batteries.

[0011] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for preparing a positive electrode catalyst material for lithium-sulfur batteries, the specific preparation steps of which are as follows:

[0012] Step S1: Preparation of three-dimensional porous graphene

[0013] Three-dimensional porous graphene was prepared using a sacrificial aminated silica hard template method. The aminated silica hard template was ultrasonically dispersed uniformly in deionized water, and then a graphene oxide solution was added and stirred until uniformly mixed. After standing, the mixture was washed with water and then freeze-dried and microwave-heated to reduce the carbonyl and carboxyl groups in the graphene oxide to generate graphene. The silica hard template was then removed by treatment with hydrofluoric acid solution. After the reaction was completed, the three-dimensional porous graphene was obtained by washing with water and drying.

[0014] Step S2: Preparation of In2O3@LiNbO3 catalyst

[0015] The nanocatalyst In2O3 and the ferroelectric piezoelectric material LiNbO3 were ball-milled and mixed uniformly in a ball mill to obtain the In2O3@LiNbO3 catalyst.

[0016] Step S3: Preparation of three-dimensional porous graphene@In2O3@LiNbO3 catalyst

[0017] The In2O3@LiNbO3 catalyst obtained in step S2 was added to anhydrous ethanol and mixed evenly. Then, the three-dimensional porous graphene obtained in step S1 was added and mixed evenly. The mixture was then heated until the anhydrous ethanol evaporated and dried to obtain the three-dimensional porous graphene@In2O3@LiNbO3 catalyst.

[0018] Step S4: Preparation of three-dimensional porous graphene@In2O3@LiNbO3@S cathode catalyst material

[0019] The three-dimensional porous graphene@In2O3@LiNbO3 catalyst obtained in step S3 is mixed evenly with elemental sulfur, and then the mixture is transferred to a tube furnace and calcined at 150~160℃ for 4~8h in an oxygen-free atmosphere to finally obtain the three-dimensional porous graphene@In2O3@LiNbO3@S cathode catalyst material, which is the cathode catalyst material for lithium-sulfur batteries.

[0020] Further specifying, the specific preparation process of the aminated silica hard template in step S1 is as follows: 0.3~0.5g of surfactant hexadecyltrimethylammonium bromide is ultrasonically and uniformly dispersed in deionized water; 1.2~1.6 mL of 1~3 M NaOH solution is added under water bath conditions; the water bath is heated to 70~90℃ and stirred for 20~40 min; then 2.3~2.5 mL of tetraethyl silicate is added and stirring is continued for 4~6 min; then 0.1~0.3 mL of coupling agent 3-aminopropyltrimethoxysilane is added, and stirring is continued for 1~3 h before cooling to room temperature; then the aminated silica hard template is obtained by washing with water and drying.

[0021] Further specifying, the mass ratio of the aminated silica hard template to graphene oxide in step S1 is 8~12:1, and the concentration of the graphene oxide solution is 0.1~1 mg / mL.

[0022] Further specifying, the freeze-drying temperature in step S1 is -80~-50℃, and the freeze-drying time is 8~48 h; the microwave heating power is 350~600 W, and the microwave heating time is 2~7 min.

[0023] Further specifying, the mass ratio of the nanocatalyst In2O3 to the ferroelectric piezoelectric material LiNbO3 in step S2 is 1:0.01~0.07.

[0024] Further specifying, the mass ratio of the In2O3@LiNbO3 catalyst to the three-dimensional porous graphene in step S3 is 0.2~4:1.

[0025] Further specifying, the mass ratio of the three-dimensional porous graphene@In2O3@LiNbO3 to elemental sulfur in step S4 is 3:5~10.

[0026] Further specifying, in step S4, the catalyst In2O3 and the ferroelectric piezoelectric material LiNbO3 in the three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material are co-loaded in the graphene conductive network. By utilizing the piezoelectric effect induced by stress in LiNbO3 during charge-discharge cycles, a dynamic local micro-electric field is constructed in situ. The migration behavior of LiPSs is directionally regulated by the electric field force and the interaction between LiPSs and the catalytic active sites of In2O3 is strengthened. This significantly reduces the reaction energy barrier for the conversion of LiPSs into the insoluble discharge product Li2S, achieving efficient adsorption and rapid complete conversion of LiPSs. This fundamentally breaks the shuttle effect, thereby significantly improving the rate performance and long-cycle stability of lithium-sulfur batteries.

[0027] Application of the lithium-sulfur battery cathode catalyst material prepared by the above method in the preparation of lithium-sulfur battery cathode materials.

[0028] Application of lithium-sulfur battery cathode materials prepared by the above method in the assembly of lithium-sulfur batteries.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] 1. This invention prepares a three-dimensional porous graphene support using a sacrificial template method. Its three-dimensional interconnected hierarchical pore structure forms a strong physical confinement, directly inhibiting the migration and diffusion of LiPSs from a spatial perspective. Traditional nano-SiO2 surface silanol groups exhibit extremely low reactivity, requiring multiple activation steps for grafting modification, resulting in a complex and inefficient process. This invention innovatively employs a one-step strategy: simultaneously introducing an amino-modified silane coupling agent into a tetraethyl orthosilicate alkaline hydrolysis system. Utilizing the in-situ bonding at the inorganic-organic interface during hydrolysis, amino groups are directly covalently grafted onto the SiO2 surface, achieving highly efficient amino modification. This method eliminates the need for pre-activation treatment, significantly simplifying the preparation process, and provides uniform and controllable amino grafting density, laying a crucial foundation for subsequent assembly with graphene oxide.

[0031] 2. Graphene oxide, due to the negative charge of its ionized carboxyl groups, can be stably dispersed in aqueous solutions through electrostatic repulsion. This invention utilizes a one-step prepared aminated SiO2 hard template with a positively charged surface to form an electrostatic interaction with the negatively charged carboxyl groups of graphene oxide, achieving directional self-assembly. After removing the SiO2 template by acid etching, porous graphene with a three-dimensional interconnected pore structure is obtained. This preparation process eliminates the need for complex template removal techniques, and by precisely controlling the SiO2 template particle size to approximately 120 nm, precise control of the graphene pore size can be achieved, providing an ideal carrier for the loading of active materials and the uniform distribution of catalytic sites.

[0032] 3. Based on a three-dimensional porous graphene support, this invention co-loads the nanocatalyst In2O3 and the ferroelectric piezoelectric material LiNbO3 into a graphene conductive network. By utilizing the piezoelectric effect induced by stress in LiNbO3 during charge-discharge cycles, a dynamic local micro-electric field is constructed in situ. The migration behavior of LiPSs is directionally regulated by the electric field force, and the interaction between LiPSs and the catalytic active sites of In2O3 is strengthened. This significantly reduces the reaction energy barrier for the conversion of LiPSs into the insoluble discharge product Li2S, achieving efficient adsorption and rapid complete conversion of LiPSs. This fundamentally solves the shuttle effect, thereby significantly improving the rate performance and long-cycle stability of lithium-sulfur batteries.

[0033] 4. The three-dimensional porous graphene in this invention has a large specific surface area, high porosity and continuous conductive network, which can improve the performance of lithium-sulfur batteries from multiple dimensions: (1) It inhibits the shuttle diffusion of LiPSs through physical confinement, and at the same time alleviates the volume expansion of sulfur cathode by more than 80% during charging and discharging; (2) It provides a fast channel for electron and ion transport, significantly improving the rate performance of the electrode; (3) The rich pore structure and surface sites provide support for the uniform loading of In2O3 and LiNbO3 catalysts, avoiding catalyst agglomeration. In order to ensure the synergistic effect of each component, this invention precisely matches the size of the catalyst and the template: commercial In2O3 and LiNbO3 with particle sizes of 50 nm are selected, and the particle size of SiO2 hard template is set to 120 nm. This size design allows the catalyst to be uniformly filled in the three-dimensional graphene channels, which not only ensures the full exposure of the catalytic sites, but also avoids the catalyst from falling off during the cycle through spatial confinement, thus maintaining the catalytic activity for a long time.

[0034] 5. The composite catalytic system constructed in this invention achieves efficient conversion and shuttle inhibition of LiPSs through the synergistic effect of three mechanisms: (1) Selective catalytic regulation of In2O3: The In2O3 catalyst can precisely regulate the sulfur conversion path through a two-step catalytic mechanism: during discharge, it reduces the conversion rate of elemental sulfur to soluble LiPSs, and at the same time, by generating LiInS2 intermediate, it accelerates the reduction reaction of soluble LiPSs to insoluble Li2S, thereby reducing the accumulation of LiPSs in the electrolyte from the source and inhibiting the shuttle effect. (2) Enhancement of piezoelectric micro-field of LiNbO3: During the charging and discharging process, the LiNbO3 ferroelectric piezoelectric material is subjected to lithiation stress and volume expansion, which can generate a local micro-field in situ. The electric field force can not only drive LiPSs to migrate to the catalytic site in a directional manner, but also enhance the interaction between the catalyst and LiPSs through the polarization effect, accelerating its conversion into insoluble products; at the same time, the piezoelectric effect caused by volume expansion can dynamically enhance the electric field strength, thereby achieving an adaptive improvement in catalytic efficiency. (3) Spatial confinement and conductivity enhancement of three-dimensional graphene: The physical confinement effect of three-dimensional porous graphene can further limit the diffusion range of LiPSs. At the same time, its high conductivity provides sufficient electrons for catalytic reaction, promotes the continuous performance of the piezoelectric effect of LiNbO3, and forms a closed-loop synergy of "catalysis-electric field-confinement" to achieve rapid and continuous conversion of LiPSs.

[0035] 6. This invention, through precise design of material structure and synergistic effect of multiple mechanisms, fundamentally solves the core problems of LiPSs shuttle effect, slow reaction kinetics and volume expansion in lithium-sulfur batteries, significantly improves the long-cycle stability and rate performance of lithium-sulfur batteries, and provides key technical support for the commercial application of lithium-sulfur batteries. Attached Figure Description

[0037] Figure 1 This is a TEM image of the three-dimensional porous graphene@In2O3@LiNbO3 catalyst obtained in Example 1.

[0038] Figure 2 This is an infrared image of the three-dimensional porous graphene obtained in Example 1.

[0039] Figure 3 This is a comparison chart of the rate charge-discharge performance of the catalytic materials prepared in each embodiment and comparative example. Detailed Implementation

[0041] This invention suppresses the shuttle effect of LiPSs by constructing three-dimensional porous graphene @In2O3@LiNbO3@S, solves the problems of S expansion and poor conductivity, and thus improves its electrochemical performance.

[0042] This invention specifically prepares lithium-sulfur battery cathode catalyst materials through the following method, including the following steps:

[0043] (1) Preparation of aminated silica hard template

[0044] 0.3–0.5 g of surfactant hexadecyltrimethylammonium bromide was ultrasonically and uniformly dispersed in deionized water; 1.2–1.6 mL of 1–3 M NaOH solution was added under water bath conditions; the mixture was heated to 70–90 °C and stirred for 20–40 min; then 2.3–2.5 mL of tetraethyl silicate was added and stirring was continued for 4–6 min; then 0.1–0.3 mL of coupling agent 3-aminopropyltrimethoxysilane was added, and stirring was continued for 1–3 h before cooling to room temperature; finally, the mixture was washed with water and dried to obtain an aminated silica hard template.

[0045] (2) Preparation of graphene oxide solution

[0046] Graphene oxide solution was prepared using the classic "Hummers method" for graphene oxide preparation. For example, expanded graphite was treated with concentrated sulfuric acid and potassium permanganate, and the reaction temperature was controlled in stages during the reaction. The reaction product was washed and then dialyzed to obtain a graphene oxide solution of a certain concentration (optionally 0.1~1 mg / mL).

[0047] As an example, the present invention is prepared by the following method:

[0048] Under ice bath conditions, expanded graphite was added to concentrated sulfuric acid at 0°C and stirred until homogeneous. Potassium permanganate was then added at temperatures below 10°C. The reaction was then carried out sequentially under stirring at low temperatures of 10–15°C, medium temperatures of 35°C, and high temperatures of 85–95°C. After the reaction, distilled water was added to dilute the solution, and an appropriate amount of hydrogen peroxide was added until the solution turned bright yellow. The solution was allowed to stand, centrifuged to obtain the precipitate, and then subjected to acid washing and distilled water washing. For SO4-free... 2- A neutral graphene oxide solution was dialyzed, diluted, stirred, and sonicated to obtain a graphene oxide solution.

[0049] (3) Preparation of three-dimensional porous graphene

[0050] Three-dimensional porous graphene was prepared using a sacrificial aminated silica hard template method. The aminated silica hard template was dispersed in an appropriate amount of deionized water and ultrasonically dispersed until uniform. A certain amount of graphene oxide solution (optionally, the mass ratio of aminated silica hard template to graphene oxide is 8~12:1) was slowly added, and the mixture was magnetically stirred for 2 h, then allowed to stand for 2 h. After washing with water, the graphene oxide was freeze-dried (optionally at -80~-50℃ for 8~48 h) and microwave-treated (optionally at 350~600 W for 2~7 min) to reduce the carbonyl and carboxyl groups in the graphene oxide to form graphene. After treatment with hydrofluoric acid solution to remove silica, and after a reaction of 2 h, the graphene oxide was washed with water and dried to obtain three-dimensional porous graphene.

[0051] (4) Preparation of In2O3@LiNbO3 catalyst

[0052] The nano-catalyst In2O3 and the ferroelectric piezoelectric material LiNbO3 were weighed in a certain proportion (the mass ratio of nano-catalyst In2O3 and ferroelectric piezoelectric material LiNbO3 can be 1:0.01~0.07), and ball-milled in a ball mill at 400 rad / min for 8 h to make them uniformly mixed to obtain the In2O3@LiNbO3 catalyst.

[0053] (5) Preparation of three-dimensional porous graphene@In2O3@LiNbO3 catalyst

[0054] In2O3@LiNbO3 catalyst and three-dimensional porous graphene were weighed at a certain mass ratio (the mass ratio of In2O3@LiNbO3 catalyst to three-dimensional porous graphene could be 0.2~4:1). The three-dimensional porous graphene was immersed in a uniformly mixed anhydrous ethanol solution of In2O3@LiNbO3 catalyst, sonicated for 1 h, heated until the anhydrous ethanol evaporated, and dried to obtain the three-dimensional porous graphene@In2O3@LiNbO3 catalyst.

[0055] (6) Preparation of three-dimensional porous graphene @In2O3@LiNbO3@S

[0056] Three-dimensional porous graphene@In2O3@LiNbO3 and elemental sulfur are mixed uniformly at a certain mass ratio (the mass ratio of three-dimensional porous graphene@In2O3@LiNbO3 to elemental sulfur can be 3:5~10). Then, the mixture is transferred to a tube furnace and calcined under an oxygen-free atmosphere (optionally nitrogen protection) (optionally calcination temperature is 150~160℃, calcination time is 4~8 h) to obtain three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material.

[0057] The cathode catalytic material prepared by the above method can be further applied in lithium-sulfur batteries, specifically as a cathode material for assembling lithium-sulfur batteries.

[0058] To better illustrate the above technical solutions, detailed descriptions of specific embodiments will be provided below. However, this should not be construed as limiting the scope of the invention to the following embodiments; all technologies implemented based on the above content of this invention fall within the scope of this invention.

[0059] Example 1

[0060] Step S1: Preparation of aminated silica hard template: 0.4 g of surfactant hexadecyltrimethylammonium bromide was dispersed in an appropriate amount of deionized water and ultrasonically dispersed; 1.4 mL of 2 M NaOH solution was added under water bath conditions; the water bath was heated to 80℃ and stirred for 30 min; then 2.4 mL of tetraethyl silicate was added and stirred for another 5 min; then 0.2 mL of coupling agent 3-aminopropyltrimethoxysilane was added and stirred for 2 h; the mixture was cooled to room temperature; and then the aminated silica hard template was obtained by washing with water and drying.

[0061] Step S2: Preparation of graphene oxide solution: Add 46 mL of concentrated sulfuric acid to a 250 mL dry beaker and stir magnetically under ice bath conditions. When the temperature reaches 0℃, slowly add 2 g of expanded graphite. After stirring evenly, continue to slowly add 6 g of potassium permanganate (keeping the temperature below 10℃). Remove some ice and maintain the temperature at 10~15℃, stirring continuously for 2 h (low-temperature reaction). Then, place the beaker in a 35℃ constant temperature water bath and continue stirring for 30 min (medium-temperature reaction). Finally, transfer the beaker to a 90℃ water bath and keep stirring, adding distilled water (about 50 mL) dropwise, strictly controlling the temperature at 90~95℃ (high-temperature reaction). After the reaction is complete, transfer the solution to a 1000 mL beaker and dilute with distilled water to 800 mL. Add an appropriate amount of 5wt% hydrogen peroxide until the solution turns bright yellow. Let stand until precipitation is complete, then discard the supernatant. The precipitate was separated by centrifugation, and the supernatant was washed with 5 wt% hydrochloric acid until no SO4 was found in the supernatant. 2- (Tested with 5wt% BaCl2) Then wash with distilled water until the supernatant is neutral (tested with pH paper) to obtain a graphite oxide solution. The above graphite oxide solution is placed in a dialysis bag and dialyzed for one week. Dilute with distilled water to a certain volume, stir for 1 h, and sonicate for 1 h. The concentration is measured to be 0.5 mg / mL using the constant weight method.

[0062] Step S3: Preparation of three-dimensional porous graphene: Three-dimensional porous graphene was prepared using the sacrificial aminated silica hard template method. 750 mg of the aminated silica hard template from step S1 was dispersed in an appropriate amount of deionized water and ultrasonically dispersed until uniform. 150 mL of a 0.5 mg / mL graphene oxide solution from step S2 was slowly added, and the mixture was magnetically stirred for 2 h and then allowed to stand for 2 h. After washing with water, it was freeze-dried at -70℃ for 24 h. Subsequently, it was microwave-heated at 450 W for 4 min to reduce the carbonyl and carboxyl groups in the graphene oxide to form graphene. After treatment with hydrofluoric acid solution to remove silica, and after reacting for 2 h, it was washed with water and dried to obtain three-dimensional porous graphene.

[0063] Step S4: Preparation of In2O3@LiNbO3 catalyst: Accurately weigh the In2O3:LiNbO3 according to the mass ratio of 1:0.03, and ball mill it in a ball mill at a speed of 400 r / min for 8 h to make it uniformly mixed to obtain the In2O3@LiNbO3 catalyst.

[0064] Step S5: Preparation of three-dimensional porous graphene@In2O3@LiNbO3 catalyst: 0.1 g of In2O3@LiNbO3 catalyst was mixed evenly with anhydrous ethanol. 0.084 g of three-dimensional porous graphene was immersed in the evenly mixed anhydrous ethanol solution of In2O3@LiNbO3. After sonication for 1 h, the mixture was heated until the anhydrous ethanol evaporated and dried to obtain the three-dimensional porous graphene@In2O3@LiNbO3 catalyst.

[0065] Step S6: Preparation of three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material: The three-dimensional porous graphene@In2O3@LiNbO3 catalyst from step S5 and elemental sulfur were mixed evenly at a mass ratio of 3:7, and then transferred to a tube furnace for sintering under nitrogen protection, calcination temperature of 155℃, and holding time of 6 h to obtain the three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material.

[0066] Example 2

[0067] Step S1: Preparation of aminated silica hard template: 0.4 g of surfactant hexadecyltrimethylammonium bromide was dispersed in an appropriate amount of deionized water and ultrasonically dispersed; 1.4 mL of 2 M NaOH solution was added under water bath conditions; the water bath was heated to 80℃ and stirred for 30 min; then 2.4 mL of tetraethyl silicate was added and stirred for another 5 min; then 0.2 mL of coupling agent 3-aminopropyltrimethoxysilane was added and stirred for 2 h; the mixture was cooled to room temperature; and then the aminated silica hard template was obtained by washing with water and drying.

[0068] Step S2: Preparation of graphene oxide solution: Add 46 mL of concentrated sulfuric acid to a 250 mL dry beaker and stir magnetically under ice bath conditions. When the temperature reaches 0℃, slowly add 2 g of expanded graphite. After stirring evenly, continue to slowly add 6 g of potassium permanganate (keeping the temperature below 10℃). Remove some ice and maintain the temperature at 10~15℃, stirring continuously for 2 hours (low-temperature reaction). Then, place the beaker in a 35℃ constant temperature water bath and continue stirring for 30 minutes (medium-temperature reaction). Finally, transfer the beaker to a 90℃ water bath, stirring constantly, and add distilled water (about 50 mL) dropwise, strictly controlling the temperature at 90~95℃ (high-temperature reaction). After the reaction is complete, transfer the solution to a 1000 mL beaker and dilute with distilled water to 800 mL. Add an appropriate amount of 5wt% hydrogen peroxide until the solution turns bright yellow. Let stand until precipitation is complete, then discard the supernatant. The precipitate was separated by centrifugation, and the supernatant was washed with 5 wt% hydrochloric acid until no SO4 was found in the supernatant. 2- (Tested with 5wt% BaCl2) Then wash with distilled water until the supernatant is neutral (tested with pH paper) to obtain a graphite oxide solution. The above graphite oxide solution is placed in a dialysis bag and dialyzed for one week. Dilute with distilled water to a certain volume, stir for 1 h, and sonicate for 1 h. The concentration is measured to be 0.1 mg / mL using the constant weight method.

[0069] Step S3: Preparation of three-dimensional porous graphene: Three-dimensional porous graphene was prepared using the sacrificial aminated silica hard template method. 120 mg of the aminated silica hard template from step S1 was dispersed in an appropriate amount of deionized water and ultrasonically dispersed until uniform. 150 mL of a 0.1 mg / mL graphene oxide solution from step S2 was slowly added, and the mixture was magnetically stirred for 2 h and then allowed to stand for 2 h. After washing with water, it was freeze-dried at -80℃ for 8 h. Then, it was microwave-heated at 350 W for 2 min to reduce the carbonyl and carboxyl groups in the graphene oxide to form graphene. After treatment with hydrofluoric acid solution to remove silica, and after reacting for 2 h, it was washed with water and dried to obtain three-dimensional porous graphene.

[0070] Step S4: Preparation of In2O3@LiNbO3 catalyst: Accurately weigh In2O3:LiNbO3 according to a mass ratio of 1:0.01, and ball mill it in a ball mill at a speed of 400 r / min for 8 h to make it uniformly mixed to obtain In2O3@LiNbO3 catalyst.

[0071] Step S5: Preparation of three-dimensional porous graphene@In2O3@LiNbO3 catalyst: 0.1 g of In2O3@LiNbO3 catalyst was mixed evenly with anhydrous ethanol. 0.5 g of three-dimensional porous graphene was immersed in the evenly mixed anhydrous ethanol solution of In2O3@LiNbO3. After sonication for 1 h, the mixture was heated until the anhydrous ethanol evaporated and dried to obtain the three-dimensional porous graphene@In2O3@LiNbO3 catalyst.

[0072] Step S6: Preparation of three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material: The three-dimensional porous graphene@In2O3@LiNbO3 catalyst from step S5 and elemental sulfur were mixed evenly at a mass ratio of 3:5, and then transferred to a tube furnace for sintering under nitrogen protection, calcination temperature of 150℃, and holding time of 4 h to obtain the three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material.

[0073] Example 3

[0074] Step S1: Preparation of aminated silica hard template: 0.4 g of surfactant hexadecyltrimethylammonium bromide was dispersed in an appropriate amount of deionized water and ultrasonically dispersed; 1.4 mL of 2 M NaOH solution was added under water bath conditions; the water bath was heated to 80℃ and stirred for 30 min; then 2.4 mL of tetraethyl silicate was added and stirred for another 5 min; then 0.2 mL of coupling agent 3-aminopropyltrimethoxysilane was added and stirred for 2 h; the mixture was cooled to room temperature; and then the aminated silica hard template was obtained by washing with water and drying.

[0075] Step S2: Preparation of graphene oxide solution: Add 46 mL of concentrated sulfuric acid to a 250 mL dry beaker and stir magnetically under ice bath conditions. When the temperature reaches 0℃, slowly add 2 g of expanded graphite. After stirring evenly, continue to slowly add 6 g of potassium permanganate (keeping the temperature below 10℃). Remove some ice and maintain the temperature at 10~15℃, stirring continuously for 2 hours (low-temperature reaction). Then, place the beaker in a 35℃ constant temperature water bath and continue stirring for 30 min (medium-temperature reaction). Finally, transfer the beaker to a 90℃ water bath, stirring continuously, and add distilled water (about 50 mL) dropwise, strictly controlling the temperature at 90~95℃ (high-temperature reaction). After the reaction is complete, transfer the solution to a 1000 mL beaker and dilute with distilled water to 800 mL. Add an appropriate amount of 5wt% hydrogen peroxide until the solution turns bright yellow. Let stand until precipitation is complete, then discard the supernatant. The precipitate was separated by centrifugation, and the supernatant was washed with 5 wt% hydrochloric acid until no SO4 was found in the supernatant. 2-(Tested with 5wt% BaCl2) Then wash with distilled water until the supernatant is neutral (tested with pH paper) to obtain a graphite oxide solution. Place the above graphite oxide solution into a dialysis bag and dialyze for one week. Dilute with distilled water to a certain volume, stir for 1 h, and sonicate for 1 h. Measure its concentration (1 mg / mL) using the constant weight method.

[0076] Step S3: Preparation of three-dimensional porous graphene: Three-dimensional porous graphene was prepared using the sacrificial aminated silica hard template method. 1800 mg of the aminated silica hard template from step S1 was dispersed in an appropriate amount of deionized water and ultrasonically dispersed until uniform. 150 mL of a 1 mg / mL graphene oxide solution from step S2 was slowly added, and the mixture was magnetically stirred for 2 h and then allowed to stand for 2 h. After washing with water, it was freeze-dried at -50℃ for 48 h. Subsequently, it was microwave-heated at 600 W for 7 min to reduce the carbonyl and carboxyl groups in the graphene oxide to form graphene. After treatment with hydrofluoric acid solution to remove silica, and after reacting for 2 h, it was washed with water and dried to obtain three-dimensional porous graphene.

[0077] Step S4: Preparation of In2O3@LiNbO3 catalyst: Accurately weigh the In2O3:LiNbO3 according to the mass ratio of 1:0.07, and ball mill it in a ball mill at a speed of 400 r / min for 8 h to make it uniformly mixed to obtain the In2O3@LiNbO3 catalyst.

[0078] Step S5: Preparation of three-dimensional porous graphene@In2O3@LiNbO3 catalyst: 0.1 g of In2O3@LiNbO3 catalyst was mixed evenly with anhydrous ethanol. 0.025 g of three-dimensional porous graphene was immersed in the evenly mixed In2O3@LiNbO3 anhydrous ethanol solution, sonicated for 1 h, heated until the anhydrous ethanol evaporated, and dried to obtain the three-dimensional porous graphene@In2O3@LiNbO3 catalyst.

[0079] Step S6: Preparation of three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material: The three-dimensional porous graphene@In2O3@LiNbO3 catalyst from step S5 and elemental sulfur were mixed evenly at a mass ratio of 3:10, and then transferred to a tube furnace for sintering under nitrogen protection, calcination temperature of 160℃, and holding time of 8 h to obtain the three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material.

[0080] Comparative Example 1 (using only ordinary graphene)

[0081] Step S1: Preparation of graphene oxide solution: Add 46 mL of concentrated sulfuric acid to a 250 mL dry beaker and stir magnetically under ice bath conditions. When the temperature reaches 0℃, slowly add 2 g of expanded graphite. After stirring evenly, continue to slowly add 6 g of potassium permanganate (keeping the temperature below 10℃). Remove some ice and maintain the temperature at 10~15℃, stirring continuously for 2 h (low-temperature reaction). Then, place the beaker in a 35℃ constant temperature water bath and continue stirring for 30 min (medium-temperature reaction). Finally, transfer the beaker to a 90℃ water bath and keep stirring, adding distilled water (about 50 mL) dropwise, strictly controlling the temperature at 90~95℃ (high-temperature reaction). After the reaction is complete, transfer the solution to a 1000 mL beaker and dilute with distilled water to 800 mL. Add an appropriate amount of 5wt% hydrogen peroxide until the solution turns bright yellow. Let stand until precipitation is complete, then discard the supernatant. The precipitate was separated by centrifugation, and the supernatant was washed with 5 wt% hydrochloric acid until no SO4 was found in the supernatant. 2- (Tested with 5wt% BaCl2) Then wash with distilled water until the supernatant is neutral (tested with pH paper) to obtain a graphite oxide solution. The above graphite oxide solution is placed in a dialysis bag and dialyzed for one week. Dilute with distilled water to a certain volume, stir for 1 h, and sonicate for 1 h. The concentration is measured to be 0.5 mg / mL using the constant weight method.

[0082] Step S2: Weigh 150 mL of the graphene oxide solution with a concentration of 0.5 mg / mL obtained in step S1, stir magnetically for 2 h, and let stand for 2 h; wash with water, freeze dry at -70℃ for 24 h; then microwave heat treatment at 450 W for 4 min to reduce the carbonyl and carboxyl groups in the graphene oxide to generate graphene.

[0083] Step S3: Preparation of In2O3@LiNbO3 catalyst: Accurately weigh In2O3:LiNbO3 according to the mass ratio of 1:0.03, and ball mill it in a ball mill at a speed of 400 r / min for 8 h to make it uniformly mixed to obtain In2O3@LiNbO3 catalyst.

[0084] Step S4: Preparation of graphene@In2O3@LiNbO3 catalyst: 0.1 g of the In2O3@LiNbO3 catalyst obtained in step S3 was mixed evenly with anhydrous ethanol. 0.084 g of the graphene obtained in step S2 was immersed in the evenly mixed anhydrous ethanol solution of In2O3@LiNbO3. After sonication for 1 h, the mixture was heated until the anhydrous ethanol evaporated and dried to obtain the graphene@In2O3@LiNbO3 catalyst.

[0085] Step S5: Preparation of graphene@In2O3@LiNbO3@S catalytic material: The graphene@In2O3@LiNbO3 catalyst obtained in step S4 and elemental sulfur were mixed evenly at a mass ratio of 3:7, and then transferred to a tube furnace for sintering under nitrogen protection, calcination temperature of 155℃ and holding time of 6 h to obtain graphene@In2O3@LiNbO3@S catalytic material.

[0086] Comparative Example 2 (without LiNbO3)

[0087] Step S1: Preparation of aminated silica hard template: 0.4 g of surfactant hexadecyltrimethylammonium bromide was dispersed in an appropriate amount of deionized water and ultrasonically dispersed; 1.4 mL of 2 M NaOH solution was added under water bath conditions; the water bath was heated to 80℃ and stirred for 30 min; then 2.4 mL of tetraethyl silicate was added and stirred for another 5 min; then 0.2 mL of coupling agent 3-aminopropyltrimethoxysilane was added and stirred for 2 h; the mixture was cooled to room temperature; and then the aminated silica hard template was obtained by washing with water and drying.

[0088] Step S2: Preparation of graphene oxide solution: Add 46 mL of concentrated sulfuric acid to a 250 mL dry beaker and stir magnetically under ice bath conditions. When the temperature reaches 0℃, slowly add 2 g of expanded graphite. After stirring evenly, continue to slowly add 6 g of potassium permanganate (keeping the temperature below 10℃). Remove some ice and maintain the temperature at 10~15℃, stirring continuously for 2 h (low-temperature reaction). Then, place the beaker in a 35℃ constant temperature water bath and continue stirring for 30 min (medium-temperature reaction). Finally, transfer the beaker to a 90℃ water bath and keep stirring, adding distilled water (about 50 mL) dropwise, strictly controlling the temperature at 90~95℃ (high-temperature reaction). After the reaction is complete, transfer the solution to a 1000 mL beaker and dilute with distilled water to 800 mL. Add an appropriate amount of 5wt% hydrogen peroxide until the solution turns bright yellow. Let stand until precipitation is complete, then discard the supernatant. The precipitate was separated by centrifugation, and the supernatant was washed with 5 wt% hydrochloric acid until no SO4 was found in the supernatant. 2- (Tested with 5wt% BaCl2) Then wash with distilled water until the supernatant is neutral (tested with pH paper) to obtain a graphite oxide solution. The above graphite oxide solution is placed in a dialysis bag and dialyzed for one week. Dilute with distilled water to a certain volume, stir for 1 h, and sonicate for 1 h. The concentration is measured to be 0.5 mg / mL using the constant weight method.

[0089] Step S3: Preparation of three-dimensional porous graphene: Three-dimensional porous graphene was prepared using the sacrificial aminated silica hard template method. 750 mg of the aminated silica hard template from step S1 was dispersed in an appropriate amount of deionized water and ultrasonically dispersed until uniform. 150 mL of a 0.5 mg / mL graphene oxide solution from step S2 was slowly added, and the mixture was magnetically stirred for 2 h and then allowed to stand for 2 h. After washing with water, it was freeze-dried at -70℃ for 24 h. Subsequently, it was microwave-heated at 450 W for 4 min to reduce the carbonyl and carboxyl groups in the graphene oxide to form graphene. After treatment with hydrofluoric acid solution to remove silica, and after reacting for 2 h, it was washed with water and dried to obtain three-dimensional porous graphene.

[0090] Step S4: Preparation of three-dimensional porous graphene@In2O3 catalyst: 0.1 g of nano-catalyst In2O3 was mixed evenly with anhydrous ethanol. 0.084 g of three-dimensional porous graphene was immersed in the evenly mixed anhydrous ethanol solution of In2O3. After sonication for 1 h, the mixture was heated until the anhydrous ethanol evaporated and dried to obtain the three-dimensional porous graphene@In2O3 catalyst.

[0091] Step S5: Preparation of three-dimensional porous graphene@In2O3@S catalytic material: The three-dimensional porous graphene@In2O3 catalyst and elemental sulfur from step S4 were mixed evenly at a mass ratio of 3:7, and then transferred to a tube furnace for sintering under nitrogen protection, calcination temperature of 155℃ and holding time of 6 h to obtain the three-dimensional porous graphene@In2O3@S catalytic material.

[0092] Comparative Example 3 (without the addition of three-dimensional porous graphene)

[0093] Step S1: Preparation of In2O3@LiNbO3 catalyst: Accurately weigh In2O3:LiNbO3 according to the mass ratio of 1:0.03, and ball mill it in a ball mill at a speed of 400 r / min for 8 h to make it uniformly mixed to obtain In2O3@LiNbO3 catalyst.

[0094] Step S2: Preparation of In2O3@LiNbO3@S catalytic material: The In2O3@LiNbO3 catalyst obtained in step S1 and elemental sulfur were mixed evenly at a mass ratio of 3:7, and then transferred to a tube furnace for sintering under nitrogen protection, calcination temperature of 155℃ and holding time of 6 h to obtain the In2O3@LiNbO3@S catalytic material.

[0095] Product performance testing:

[0096] Electrode preparation and coin cell assembly are carried out before electrochemical testing, and then the battery's electrical performance is tested using a charge-discharge test cabinet.

[0097] from Figure 1 The TEM results show that the In2O3@LiNbO3 catalyst prepared according to the method of Example 1 is uniformly supported in three-dimensional porous graphene.

[0098] from Figure 2 The infrared results show that the three-dimensional porous graphene synthesized according to the method of Example 1, although at 1170 cm⁻¹, -1 A stretching vibration peak of COC appeared nearby, but its intensity was much weaker than that of graphene oxide. Furthermore, the absorption peaks of other oxygen-containing functional groups (-OH, -C=O, -COOH, etc.) significantly weakened or even disappeared. Simultaneously, a C=C peak (1570 cm⁻¹) appeared. -1 The stretching vibration peak indicates that most of the oxygen-containing functional groups in graphene oxide have been removed, and the six-membered ring structure of carbon atoms has been restored to a certain extent. Graphene oxide has been reduced to graphene, demonstrating that the microwave method for reducing graphene oxide is quite thorough.

[0099] from Figure 3 The electrical performance test results show that the three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material prepared in Example 1 of this invention has better rate performance and capacity recovery performance.

[0100] Based on the above experimental results, it can be seen that this invention, through the construction of three-dimensional porous graphene and the simultaneous incorporation of key factors such as catalysts In2O3 and LiNbO3, can achieve the control of the microstructure properties of lithium-sulfur battery cathode materials, constructing a unique "confined-local micro-electric field assisted-accelerated catalytic conversion" lithium-sulfur battery catalytic material, effectively suppressing the shuttle effect of LiPSs. The design of the three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material constructed in Example 1 of this invention achieves multifunctional coupling: this structure not only solves the problem of poor conductivity of sulfur, but also effectively suppresses the shuttle effect of LiPSs, achieving a comprehensive improvement in high-rate charge-discharge performance and stability. Comparative studies show that using a single material structure or lacking key components (Comparative Examples 1-3) and improper control of key parameters during preparation (Examples 2-3) cannot simultaneously and effectively solve the problem of LiPSs shuttle effect and battery electrochemical performance improvement, further highlighting the necessity and superiority of the multi-component synergistic design and precise control of this invention.

[0101] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A method for preparing a positive electrode catalyst material for lithium-sulfur batteries, characterized in that... The specific preparation steps are as follows: Step S1: Preparation of three-dimensional porous graphene Three-dimensional porous graphene was prepared using a sacrificial aminated silica hard template method. The aminated silica hard template was ultrasonically dispersed uniformly in deionized water, and then a graphene oxide solution was added and stirred until uniformly mixed. After standing, the mixture was washed with water and then freeze-dried and microwave-heated to reduce the carbonyl and carboxyl groups in the graphene oxide to generate graphene. The silica hard template was then removed by treatment with hydrofluoric acid solution. After the reaction was completed, the three-dimensional porous graphene was obtained by washing with water and drying. Step S2: Preparation of In2O3@LiNbO3 catalyst The nanocatalyst In2O3 and the ferroelectric piezoelectric material LiNbO3 were ball-milled and mixed uniformly in a ball mill to obtain the In2O3@LiNbO3 catalyst. Step S3: Preparation of three-dimensional porous graphene@In2O3@LiNbO3 catalyst The In2O3@LiNbO3 catalyst obtained in step S2 was added to anhydrous ethanol and mixed evenly. Then, the three-dimensional porous graphene obtained in step S1 was added and mixed evenly. The mixture was then heated until the anhydrous ethanol evaporated and dried to obtain the three-dimensional porous graphene@In2O3@LiNbO3 catalyst. Step S4: Preparation of three-dimensional porous graphene@In2O3@LiNbO3@S cathode catalyst material The three-dimensional porous graphene@In2O3@LiNbO3 catalyst obtained in step S3 is mixed evenly with elemental sulfur, and then the mixture is transferred to a tube furnace and calcined at 150~160℃ for 4~8h in an oxygen-free atmosphere to finally obtain the three-dimensional porous graphene@In2O3@LiNbO3@S cathode catalyst material, which is the cathode catalyst material for lithium-sulfur batteries.

2. The method for preparing the lithium-sulfur battery cathode catalyst material according to claim 1, characterized in that... The specific preparation process of the aminated silica hard template in step S1 is as follows: 0.3~0.5 g of surfactant cetyltrimethylammonium bromide is ultrasonically and uniformly dispersed in deionized water; 1.2~1.6 mL of 1~3 M NaOH solution is added under water bath conditions; the water bath is heated to 70~90℃ and stirred for 20~40 min; then 2.3~2.5 mL of tetraethyl silicate is added and stirred for 4~6 min; then 0.1~0.3 mL of coupling agent 3-aminopropyltrimethoxysilane is added and stirred for 1~3 h, and then cooled to room temperature; then the aminated silica hard template is obtained by washing with water and drying.

3. The method for preparing the lithium-sulfur battery cathode catalyst material according to claim 1, characterized in that: In step S1, the mass ratio of aminated silica hard template to graphene oxide is 8~12:1, and the concentration of graphene oxide solution is 0.1~1 mg / mL.

4. The method for preparing the lithium-sulfur battery cathode catalyst material according to claim 1, characterized in that: The freeze-drying temperature in step S1 is -80~-50℃, and the freeze-drying time is 8~48 h; the microwave heating power is 350~600 W, and the microwave heating time is 2~7 min.

5. The method for preparing the lithium-sulfur battery cathode catalyst material according to claim 1, characterized in that: In step S2, the mass ratio of the nanocatalyst In2O3 to the ferroelectric piezoelectric material LiNbO3 is 1:0.01~0.

07.

6. The method for preparing the lithium-sulfur battery cathode catalyst material according to claim 1, characterized in that: In step S3, the mass ratio of the In2O3@LiNbO3 catalyst to the three-dimensional porous graphene is 0.2~4:

1.

7. The method for preparing the lithium-sulfur battery cathode catalyst material according to claim 1, characterized in that: In step S4, the mass ratio of the three-dimensional porous graphene @In2O3@LiNbO3 to elemental sulfur is 3:5~10.

8. The method for preparing the lithium-sulfur battery cathode catalyst material according to claim 1, characterized in that: In step S4, the catalyst In2O3 and the ferroelectric piezoelectric material LiNbO3 in the three-dimensional porous graphene@In2O3@LiNbO3@S catalytic material are co-loaded in the graphene conductive network. By utilizing the piezoelectric effect induced by stress in LiNbO3 during charge-discharge cycles, a dynamic local micro-electric field is constructed in situ. The migration behavior of LiPSs is directionally regulated by the electric field force and the interaction between LiPSs and the catalytic active sites of In2O3 is strengthened. This significantly reduces the reaction energy barrier for the conversion of LiPSs into the insoluble discharge product Li2S, achieving efficient adsorption and rapid complete conversion of LiPSs. This fundamentally solves the shuttle effect and thus significantly improves the rate performance and long-cycle stability of lithium-sulfur batteries.

9. The application of the lithium-sulfur battery cathode catalyst material prepared according to the method of claims 1 to 8 in the preparation of lithium-sulfur battery cathode materials.

10. The application according to claim 9, characterized in that: The lithium-sulfur battery cathode material is used to assemble lithium-sulfur batteries.

Images