Preparation method of composite sulfur positive electrode and application thereof in all-solid-state battery

Abstract

The application discloses a preparation method of a composite sulfur positive electrode and application of the composite sulfur positive electrode in a full solid-state battery, and relates to the technical field of full solid-state battery materials. The composite sulfur positive electrode is prepared by using an in-situ liquid phase process, hollow mesoporous carbon spheres are selected as carbon carriers, and the particle size and pore size of the carbon spheres are regulated to realize uniform loading of sulfide solid electrolyte particles and elemental sulfur particles in the pores of the carbon spheres, form a compact carbon carrier-sulfide solid electrolyte-sulfur three-phase interface, build a continuous and rich charge transfer path, and finally improve the utilization rate of sulfur. The full solid-state lithium-sulfur battery with the composite sulfur positive electrode prepared by the application has the advantages of superior battery performance, high safety and the like, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of all-solid-state battery material technology, specifically relating to a method for preparing a composite sulfur cathode and its application in all-solid-state batteries. Background Technology

[0002] The growing societal demand is driving the rapid development of electric vehicles and large-scale energy storage systems, presenting new requirements and challenges for high-energy-density, high-safety rechargeable batteries. Lithium-sulfur batteries possess a relatively high theoretical capacity (1675 mAh g⁻¹). −1 ) and energy density (2600Whkg) −1 Lithium-sulfur (Li-S) batteries are considered strong contenders for next-generation battery systems. Compared to traditional liquid battery systems, which suffer from issues such as polysulfide shuttling, flammability, and environmental unfriendliness, all-solid-state lithium-sulfur battery systems using sulfide solid electrolytes do not have polysulfide shuttling and employ non-flammable solid electrolytes. They are expected to be widely used as a new generation of battery systems that combine high energy density, high safety performance, and long cycle life.

[0003] Using solid-state electrolytes avoids the capacity loss and lithium metal anode corrosion caused by the dissolution of polysulfides generated from elemental sulfur in the cathode during the cycling process of liquid lithium-sulfur batteries. This is the basic idea behind the development of all-solid-state lithium-sulfur batteries. However, simply replacing the electrolyte cannot directly convert to an all-solid-state lithium-sulfur battery. In practical applications, the sulfur cathode side of all-solid-state lithium-sulfur batteries faces challenges similar to those of liquid lithium-sulfur batteries, such as sulfur insulation and volume expansion, and also has its own inherent limitations. Ion / electron transport in all-solid-state battery systems relies on solid-solid contact; however, interparticle contact is inherently incomplete. The solid electrolyte, acting as a cathode filler, constitutes the ion transport path. Unlike liquid electrolytes, solid electrolytes have limited penetration into the cathode, exacerbating the impact of solid electrolytes on the irregularities within the cathode, resulting in defects such as voids and cracks. The uniformity of the solid electrolyte distribution in the composite sulfur cathode and the tightness of its interface with the active material and conductive agent significantly affect the battery reaction kinetics. A uniform distribution of the solid electrolyte, constructing a continuous ion network, can meet the rapid ion transport requirements of all-solid-state batteries. Inhomogeneous and loose three-phase contact will increase overpotential, leading to premature battery failure. Therefore, finding a suitable composite sulfur cathode preparation method, ensuring effective ion / electron conduction, maintaining a stable internal interface, and carefully considering the composition and structure of the composite sulfur cathode are of great significance for the development of all-solid-state lithium-sulfur batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a composite sulfur cathode and its application in all-solid-state batteries, so as to solve at least one of the problems of low capacity caused by the uneven three-phase interface of the composite sulfur cathode in existing all-solid-state lithium sulfur batteries, while limiting the particle size of each component, improving sulfur utilization, and achieving higher energy density.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for preparing a composite sulfur cathode, comprising:

[0007] S1, Preparation of sulfide solid electrolyte precursors in a liquid phase system;

[0008] S2, add hollow mesoporous carbon spheres to the precursor liquid phase system, mechanically stir, remove solvent, and obtain a mixture powder;

[0009] S3, the mixture powder is sintered, and elemental sulfur is loaded onto the sintered product to obtain a composite sulfur cathode.

[0010] A further improvement of the present invention is that:

[0011] Preferably, in S1, the solvent used in the liquid phase system includes at least one of anhydrous ethanol, ethylenediamine, acetonitrile, ethylene glycol dimethyl ether, N-methylpyrrolidone, diethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl formate, methyl acetate, ethyl acetate, ethylene carbonate, methyl ethyl carbonate, n-hexane, cyclohexane, and n-heptane.

[0012] Preferably, in S1, the sulfide solid electrolyte is an Argyrodite type electrolyte with the chemical formula Li. 7-a PS 6- a X a Where a ranges from 0.5 to 1.5; X is one or more of Cl, Br, and I elements, and its room temperature ionic conductivity is not less than 1 × 10⁻⁶. -4 S / cm.

[0013] Preferably, in S2, the hollow mesoporous carbon spheres have a particle size of 200 nm to 700 nm and a specific surface area of ​​800 m². 2 g -1 ~1100m 2 g -1 The average pore size is 5nm to 15nm, and the total pore volume is 2cm³. 3 g -1 ~3.5cm 3 g -1 .

[0014] Further, in step S2, the method for preparing the hollow mesoporous carbon spheres includes the following steps:

[0015] (1) Resorcinol, formaldehyde and tetrapropoxysilane are added to a mixed solvent composed of water, anhydrous ethanol and ammonia. The mixture is mechanically stirred at a rate of 300 rpm to 1500 rpm for 6 h to 24 h at 30 °C to 50 °C in an air atmosphere. Then the mixture is centrifuged and dried to obtain a resin silica composite ball precursor. The mass ratio of resorcinol to formaldehyde is 0.5:1 to 5:1, and the mass ratio of tetrapropoxysilane to resorcinol is 5:1 to 10:1.

[0016] (2) The resin silica composite balls obtained in step (1) are heated to 400℃~900℃ at a heating rate of 0.5℃ / min~5℃ / min under an inert atmosphere and kept at the temperature for 1h~5h to obtain carbon / silica composite.

[0017] (3) The carbon / silica composite obtained in step (2) is placed in hydrofluoric acid or sodium hydroxide solution and stirred and etched at 30℃~80℃ for 6h~48h. Then, it is centrifuged, washed and dried to obtain the hollow mesoporous carbon spheres.

[0018] Furthermore, in step S3, the sintering is carried out under an inert atmosphere, the sintering temperature is 300℃~550℃, the sintering time is 5h~20h, and the heating and cooling rate is 0.5℃ / min~5℃ / min.

[0019] Furthermore, in step S3, the loaded elemental sulfur is subjected to heat treatment at a temperature of 100℃ to 200℃ for a duration of 6h to 48h.

[0020] Furthermore, the solvent removal method described in step S2 is at least one of centrifugation and evaporation;

[0021] The centrifugation process involved a speed of 7000 rpm to 11000 rpm and a time of 2 min to 4 min.

[0022] The solvent evaporation process is carried out at a temperature of 130℃ to 180℃ for a time of 6 hours to 48 hours.

[0023] Preferably, in S3, the mass ratio of the sulfide solid electrolyte, hollow mesoporous carbon spheres, and elemental sulfur in the composite sulfur cathode is one of 10:6:9, 10:3:7, and 20:3:27.

[0024] An all-solid-state battery comprising a composite sulfur cathode prepared by the above-described preparation method.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] This invention discloses a method for preparing a composite sulfur cathode and its application in all-solid-state batteries. The method employs an in-situ liquid-phase process to prepare the composite sulfur cathode. A carbon support is added during the nucleation stage of the sulfide solid electrolyte precursor synthesis, allowing the sulfide solid electrolyte precursor to directly nucleate using the carbon support as a site. Simultaneously, hollow mesoporous carbon spheres with high specific surface area, large pore volume, and controllable particle and pore size are selected as the carbon support. The capillary effect of the mesopores draws in the reaction liquid, achieving uniform dispersion and deposition of the sulfide solid electrolyte precursor particles within the pores of the hollow mesoporous carbon spheres. During the subsequent sintering process, the amorphous sulfide solid electrolyte precursor transforms into a crystalline state within the pores of the hollow mesoporous carbon spheres. This promotes a tight interface between the sulfide solid electrolyte particles and the hollow mesoporous carbon spheres, reducing void formation. Furthermore, by controlling the particle size and pore size of the hollow mesoporous carbon spheres, the particle size of the sulfide solid electrolyte particles can be limited, preventing their agglomeration and growth. Subsequently, the sublimated sulfur is thermally melted, allowing liquid elemental sulfur to flow into the hollow mesoporous carbon sphere channels. This achieves uniform loading of sulfide solid electrolyte particles and elemental sulfur particles within the hollow mesoporous carbon sphere channels, forming a tight three-phase interface of hollow mesoporous carbon spheres-sulfide solid electrolyte-sulfur. This constructs continuous and abundant charge transfer pathways, ultimately improving sulfur utilization. The all-solid-state lithium-sulfur battery using the composite sulfur cathode prepared according to this invention possesses advantages such as superior battery performance and high safety, and has broad application prospects. Attached Figure Description

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] Figure 1 SEM image of the hollow mesoporous carbon spheres prepared in Example 1;

[0029] Figure 2 SEM image of the hollow mesoporous carbon spheres prepared in Example 4;

[0030] Figure 3 SEM image of the hollow mesoporous carbon spheres prepared in Example 7;

[0031] Figure 4 SEM image of the hollow mesoporous carbon spheres prepared in Example 10;

[0032] Figure 5 SEM image of the hollow mesoporous carbon spheres prepared in Example 13;

[0033] Figure 6 SEM image of the hollow mesoporous carbon spheres prepared in Example 16;

[0034] Figure 7 The graph shows the isothermal nitrogen adsorption-desorption test results of the hollow mesoporous carbon spheres prepared in Example 1.

[0035] Figure 8 The graph shows the charge-discharge measurement results of the all-solid-state lithium-sulfur battery made from the composite sulfur cathode prepared in Example 1.

[0036] Figure 9 The graph shows the charge-discharge test results of the all-solid-state lithium-sulfur battery made from the composite sulfur cathode prepared in Example 4.

[0037] Figure 10 The graph shows the charge-discharge measurement results of the all-solid-state lithium-sulfur battery made from the composite sulfur cathode prepared in Example 7.

[0038] Figure 11 The graph shows the charge-discharge measurement results of the all-solid-state lithium-sulfur battery made from the composite sulfur cathode prepared in Comparative Example 1. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The present invention adopts the following technical solution:

[0041] Preparation of hollow mesoporous carbon spheres: Resorcinol, formaldehyde, and tetrapropoxysilane were added to a solvent and mixed, heated and stirred, centrifuged, the precipitate was collected and dried to obtain resin-silica composite spheres. The resin-silica composite spheres were calcined under an inert atmosphere, and the product was etched to obtain hollow mesoporous carbon spheres.

[0042] The mass ratio of resorcinol to formaldehyde is 0.5:1 to 5:1, and the mass ratio of tetrapropoxysilane to resorcinol is 5:1 to 10:1. The solvent includes at least one of water, anhydrous ethanol, and ammonia. The mechanical stirring is carried out at 30°C to 50°C in an air atmosphere, the stirring speed is 300 rpm to 1500 rpm, and the stirring time is 6 h to 24 h. The inert atmosphere includes at least one of argon and nitrogen. The calcination temperature is 400°C to 900°C, the calcination time is 1 h to 5 h, and the calcination heating rate is set at 0.5°C / min. -1 ~5℃min -1 The etching process uses at least one of hydrofluoric acid and sodium hydroxide. The etching method involves adding the calcined product to the reagent, stirring at 30℃~80℃ for 6h~48h, collecting the precipitate by centrifugation, washing the precipitate, and drying it to obtain hollow mesoporous carbon spheres. The hollow mesoporous carbon spheres have a particle size of 200nm~700nm and a specific surface area of ​​800m².2 g -1 ~1100m 2 g -1 The average pore size is 5nm to 15nm, and the total pore volume is 2cm³. 3 g -1 ~3.5cm 3 g -1 .

[0043] Preparation of the composite sulfur cathode: Raw materials are obtained according to the target sulfide solid electrolyte, including Li₂S, P₂S₅, and LiX, where X is one or more of Cl, Br, and I. The raw materials are placed in one or more containers according to stoichiometric ratios, mixed with a solvent, and mechanically stirred to obtain a sulfide solid electrolyte precursor mixture. Hollow mesoporous carbon spheres are added to the precursor liquid system, mechanically stirred, and the solvent is removed to obtain a mixture powder. The mixture powder is sintered, and elemental sulfur is loaded onto the sintered product to obtain the composite sulfur cathode.

[0044] The sulfide solid electrolyte is an Argyrodite type electrolyte with the chemical formula Li. 7-a PS 6-a X a Where a ranges from 0.5 to 1.5; X is one or more of Cl, Br, and I elements, and its room temperature ionic conductivity is not less than 1 × 10⁻⁶. -4 S / cm. The solvent used in the liquid phase system includes at least one selected from anhydrous ethanol, ethylenediamine, acetonitrile, ethylene glycol dimethyl ether, N-methylpyrrolidone, diethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl formate, methyl acetate, ethyl acetate, ethylene carbonate, methyl ethyl carbonate, n-hexane, cyclohexane, and n-heptane. The mechanical stirring is carried out at room temperature, the stirring speed is 200 rpm to 600 rpm, and the stirring time is 6 h to 24 h. The solvent removal method includes at least one of centrifugation and evaporation. The centrifugation speed is 7000 rpm to 11000 rpm, the centrifugation time is 2 min to 4 min, the solvent evaporation temperature is 130℃ to 180℃, and the solvent evaporation time is 6 h to 48 h. The sintering temperature is 300℃ to 550℃, the sintering time is 5 h to 20 h, and the heating / cooling rate is 0.5℃ / min to 5℃ / min. The method for loading elemental sulfur is heat treatment, wherein the heat treatment temperature is 100℃~200℃ and the heat treatment time is 6h~48h. All operations are carried out in an inert atmosphere.

[0045] Assembly of the all-solid-state battery: First, 100 mg of Li6PS5Cl was placed in a 10 mm inner diameter polyetheretherketone (PEEK) cylindrical cavity and cold-pressed at 42 MPa for 1 min using a hydraulic press. Then, composite sulfur cathode powder was evenly spread on one side of the solid electrolyte layer and cold-pressed at 420 MPa for 3 min. Finally, lithium-indium alloy and copper sheets were sequentially placed on the other side of the solid electrolyte layer and cold-pressed at 168 MPa for 3 min. All battery assembly operations were performed in an argon-filled glove box.

[0046] The following detailed description is provided through examples.

[0047] Example 1:

[0048] Preparation of hollow mesoporous carbon spheres: 60 mL of anhydrous ethanol, 20 mL of ultrapure water, and 3 mL of ammonia (25 wt% NH3) were sequentially added to a beaker and stirred continuously. 0.6 g of resorcinol was weighed and added to the mixture, and stirred thoroughly until the resorcinol was completely dissolved. 0.8 mL of 37 wt% formaldehyde aqueous solution was added, and the mixture was stirred for 15 min. Then, 5 mL of tetrapropoxysilane was added, and the mixture was stirred at 30 °C for 24 h. After stirring, the precipitate was collected by centrifugation, and the dried product was a dark brown powder precursor resin silica composite sphere. The collected product was placed in a porcelain boat and incubated in a tube furnace under a nitrogen atmosphere at 5 °C for [time missing]. -1 The temperature was increased to 600℃ at a certain rate, and the mixture was treated at 600℃ for 3 hours, then naturally cooled to room temperature. The pyrolysis products were collected, ground evenly in a mortar, and the powder was transferred to a beaker. A 4M sodium hydroxide aqueous solution was added to submerge the powder, and the mixture was stirred at 80℃ for 48 hours. The precipitate was collected by centrifugation, washed, and dried to obtain hollow mesoporous carbon spheres.

[0049] Preparation of the composite sulfur cathode: 0.2715 g of lithium sulfide, 0.4446 g of phosphorus pentasulfide, and 8 ml of tetrahydrofuran were weighed and added to container A, and stirred for 24 h at room temperature and under an inert atmosphere. 0.1837 g of lithium sulfide, 0.1699 g of lithium chloride, and 10 ml of anhydrous ethanol were weighed and added to container B, and stirred for 24 h at room temperature and under an inert atmosphere. The solution in container B was transferred to container A, and stirring continued for 24 h. 0.6418 g of hollow mesoporous carbon spheres were weighed and added to container A, and stirring continued for 24 h. The resulting mixture was centrifuged at 10000 rpm for 2 min, and the precipitate was collected and dried in a vacuum drying oven at 140 °C for 20 h. The dried product was collected and dried at 5 °C for 2 min under an argon atmosphere. -1The temperature was increased to 550℃ and sintered for 6 hours. 0.8 g of the sintered product was weighed and transferred to a mortar, and 0.45 g of sublimed sulfur was added to it. The mixture was ground for 0.5 hours to obtain a mixture. The mixture was kept at 155℃ under an inert atmosphere for 12 hours to obtain a composite sulfur cathode.

[0050] Example 2:

[0051] The preparation of hollow mesoporous carbon spheres is the same as in Example 1.

[0052] Preparation of the composite sulfur cathode: 0.2715 g of lithium sulfide, 0.4446 g of phosphorus pentasulfide, and 8 ml of tetrahydrofuran were weighed and added to container A, and stirred for 24 h at room temperature and under an inert atmosphere. 0.1837 g of lithium sulfide, 0.1699 g of lithium chloride, and 10 ml of anhydrous ethanol were weighed and added to container B, and stirred for 24 h at room temperature and under an inert atmosphere. The solution in container B was transferred to container A, and stirring continued for 24 h. 0.3209 g of hollow mesoporous carbon spheres were weighed and added to container A, and stirring continued for 24 h. The resulting mixture was centrifuged at 10000 rpm for 2 min, and the precipitate was collected and dried in a vacuum drying oven at 140 °C for 20 h. The dried product was collected and dried at 5 °C for 2 min under an argon atmosphere. -1 The temperature was increased to 550℃ and sintered for 6 hours. 1.3g of the sintered product was weighed and transferred to a mortar, and 0.7g of sublimed sulfur was added to it. The mixture was ground for 0.5 hours to obtain a mixture. The mixture was kept at 155℃ under an inert atmosphere for 12 hours to obtain a composite sulfur cathode.

[0053] Example 3:

[0054] The preparation of hollow mesoporous carbon spheres is the same as in Example 1.

[0055] Preparation of the composite sulfur cathode: 0.2715 g of lithium sulfide, 0.4446 g of phosphorus pentasulfide, and 8 ml of tetrahydrofuran were weighed and added to container A, and stirred for 24 h at room temperature and under an inert atmosphere. 0.1837 g of lithium sulfide, 0.1699 g of lithium chloride, and 10 ml of anhydrous ethanol were weighed and added to container B, and stirred for 24 h at room temperature and under an inert atmosphere. The solution in container B was transferred to container A, and stirring continued for 24 h. 0.1605 g of hollow mesoporous carbon spheres were weighed and added to container A, and stirring continued for 24 h. The resulting mixture was centrifuged at 10000 rpm for 2 min, and the precipitate was collected and dried in a vacuum drying oven at 140 °C for 20 h. The dried product was collected and dried at 5 °C for 2 min under an argon atmosphere. -1The temperature was increased to 550℃ and sintered for 6 hours. 0.46g of the sintered product was weighed and transferred to a mortar, and 0.54g of sublimed sulfur was added to it. The mixture was ground for 0.5 hours to obtain a mixture. The mixture was kept at 155℃ under an inert atmosphere for 12 hours to obtain a composite sulfur cathode.

[0056] Example 4:

[0057] Preparation of hollow mesoporous carbon spheres: 60 mL of anhydrous ethanol, 20 mL of ultrapure water, and 2 mL of ammonia (25 wt% NH3) were sequentially added to a beaker and stirred continuously. 0.6 g of resorcinol was weighed and added to the mixture, and stirred thoroughly until the resorcinol was completely dissolved. 0.8 mL of a 37 wt% formaldehyde aqueous solution was added, and stirring was continued for 15 min. Subsequently, 5 mL of tetrapropoxysilane was added, and the mixture was stirred at 30 °C for 24 h. After stirring, the precipitate was collected by centrifugation, and the dried product was a dark brown powder precursor resin silica composite sphere. The collected product was calcined at 600 °C for 2 h under a nitrogen atmosphere, with a heating rate set at 5 °C / min. -1 The pyrolysis products were collected, ground evenly in a mortar, and the powder was transferred to a beaker. 4M sodium hydroxide aqueous solution was added to submerge the powder, and the mixture was stirred at 80°C for 48 hours. The precipitate was collected by centrifugation, washed, and dried to obtain hollow mesoporous carbon spheres.

[0058] Preparation of the composite sulfur cathode: 0.4552 g of lithium sulfide, 0.4446 g of phosphorus pentasulfide, 0.3481 g of lithium bromide, and 20 ml of ethylenediamine were weighed and added to a container. The mixture was stirred for 24 h at room temperature and under an inert atmosphere. 0.6418 g of hollow mesoporous carbon spheres were weighed and added to the container, and stirring was continued for another 24 h. The resulting mixture was dried in a vacuum drying oven at 150 °C for 20 h to remove the organic solvent. The dried product was collected and dried under an argon atmosphere at 5 °C for 1 minute. -1 The temperature was increased to 550℃ and sintered for 6 hours. 0.8 g of the sintered product was weighed and transferred to a mortar, and 0.45 g of sublimed sulfur was added to it. The mixture was ground for 0.5 hours to obtain a mixture. The mixture was kept at 155℃ under an inert atmosphere for 12 hours to obtain a composite sulfur cathode.

[0059] Example 5:

[0060] The preparation of hollow mesoporous carbon spheres is the same as in Example 4.

[0061] Preparation of the composite sulfur cathode: 0.4552 g of lithium sulfide, 0.4446 g of phosphorus pentasulfide, 0.3481 g of lithium bromide, and 20 ml of ethylenediamine were weighed and added to a container. The mixture was stirred for 24 h at room temperature and under an inert atmosphere. 0.3209 g of hollow mesoporous carbon spheres were weighed and added to the container, and stirring was continued for another 24 h. The resulting mixture was dried in a vacuum drying oven at 150 °C for 20 h to remove the organic solvent. The dried product was collected and dried under an argon atmosphere at 5 °C for 1 minute. -1 The temperature was increased to 550℃ and sintered for 6 hours. 1.3g of the sintered product was weighed and transferred to a mortar, and 0.7g of sublimed sulfur was added to it. The mixture was ground for 0.5 hours to obtain a mixture. The mixture was kept at 155℃ under an inert atmosphere for 12 hours to obtain a composite sulfur cathode.

[0062] Example 6:

[0063] The preparation of hollow mesoporous carbon spheres is the same as in Example 4.

[0064] Preparation of the composite sulfur cathode: 0.4552 g of lithium sulfide, 0.4446 g of phosphorus pentasulfide, 0.3481 g of lithium bromide, and 20 ml of ethylenediamine were weighed and added to a container. The mixture was stirred for 24 h at room temperature and under an inert atmosphere. 0.1605 g of hollow mesoporous carbon spheres were weighed and added to the container, and stirring was continued for another 24 h. The resulting mixture was dried in a vacuum drying oven at 150 °C for 20 h to remove the organic solvent. The dried product was collected and dried under an argon atmosphere at 5 °C for 1 minute. -1 The temperature was increased to 550℃ and sintered for 6 hours. 0.46g of the sintered product was weighed and transferred to a mortar, and 0.54g of sublimed sulfur was added to it. The mixture was ground for 0.5 hours to obtain a mixture. The mixture was kept at 155℃ under an inert atmosphere for 12 hours to obtain a composite sulfur cathode.

[0065] Example 7:

[0066] Preparation of hollow mesoporous carbon spheres: 60 mL of anhydrous ethanol, 20 mL of ultrapure water, and 1 mL of ammonia (25 wt% NH3) were sequentially added to a beaker and stirred continuously. 0.6 g of resorcinol was weighed and added to the mixture, and stirred thoroughly until the resorcinol was completely dissolved. 0.8 mL of a 37 wt% formaldehyde aqueous solution was added, and stirring was continued for 15 min. Subsequently, 5 mL of tetrapropoxysilane was added, and the mixture was stirred at 30 °C for 24 h. After stirring, the precipitate was collected by centrifugation, and the dried product was a dark brown powder precursor resin silica composite sphere. The collected product was calcined at 600 °C for 2 h under a nitrogen atmosphere, with a heating rate set at 5 °C / min. -1The pyrolysis products were collected, ground evenly in a mortar, and the powder was transferred to a beaker. 4M sodium hydroxide aqueous solution was added to submerge the powder, and the mixture was stirred at 80°C for 48 hours. The precipitate was collected by centrifugation, washed, and dried to obtain hollow mesoporous carbon spheres.

[0067] Preparation of the composite sulfur cathode: 0.4552 g of lithium sulfide, 0.4446 g of phosphorus pentasulfide, and 0.5365 g of lithium iodide were weighed sequentially, and 10 ml of acetonitrile, 10 ml of tetrahydrofuran, and 0.5 ml of anhydrous ethanol were measured and added to a container. The mixture was stirred for 24 h at room temperature and under an inert atmosphere. 0.6418 g of hollow mesoporous carbon spheres were weighed and added to the container, and stirring was continued for another 24 h. The resulting mixture was dried in a vacuum drying oven at 130 °C for 20 h to remove the organic solvent. The dried product was collected and dried under an argon atmosphere at 5 °C for 1 minute. -1 The temperature was increased to 550℃ and sintered for 6 hours. 0.8 g of the sintered product was weighed and transferred to a mortar, and 0.45 g of sublimed sulfur was added to it. The mixture was ground for 0.5 hours to obtain a mixture. The mixture was kept at 155℃ under an inert atmosphere for 12 hours to obtain a composite sulfur cathode.

[0068] Example 8:

[0069] The preparation of hollow mesoporous carbon spheres is the same as in Example 7.

[0070] Preparation of the composite sulfur cathode: 0.4552 g of lithium sulfide, 0.4446 g of phosphorus pentasulfide, and 0.5365 g of lithium iodide were weighed sequentially, and 10 ml of acetonitrile, 10 ml of tetrahydrofuran, and 0.5 ml of anhydrous ethanol were measured and added to a container. The mixture was stirred for 24 h at room temperature and under an inert atmosphere. 0.3209 g of hollow mesoporous carbon spheres were weighed and added to the container, and stirring was continued for 24 h. The resulting mixture was dried in a vacuum drying oven at 130 °C for 20 h to remove the organic solvent. The dried product was collected and sintered at 550 °C under an argon atmosphere for 6 h. 1.3 g of the sintered product was weighed and transferred to a mortar, and 0.7 g of sublimed sulfur was added. The mixture was ground for 0.5 h to obtain a mixture, which was then kept at 155 °C under an inert atmosphere for 12 h to obtain the composite sulfur cathode.

[0071] Example 9:

[0072] The preparation of hollow mesoporous carbon spheres is the same as in Example 7.

[0073] Preparation of the composite sulfur cathode: 0.4552 g of lithium sulfide, 0.4446 g of phosphorus pentasulfide, and 0.5365 g of lithium iodide were weighed sequentially, and 10 ml of acetonitrile, 10 ml of tetrahydrofuran, and 0.5 ml of anhydrous ethanol were measured and added to a container. The mixture was stirred for 24 h at room temperature and under an inert atmosphere. 0.1605 g of hollow mesoporous carbon spheres were weighed and added to the container, and stirring was continued for another 24 h. The resulting mixture was dried in a vacuum drying oven at 130 °C for 20 h to remove the organic solvent. The dried product was collected and dried under an argon atmosphere at 5 °C for 1 minute. -1 The temperature was increased to 550℃ and sintered for 6 hours. 0.46g of the sintered product was weighed and transferred to a mortar, and 0.54g of sublimed sulfur was added to it. The mixture was ground for 0.5 hours to obtain a mixture. The mixture was kept at 155℃ under an inert atmosphere for 12 hours to obtain a composite sulfur cathode.

[0074] Example 10:

[0075] Preparation of hollow mesoporous carbon spheres: 70 mL of anhydrous ethanol, 10 mL of ultrapure water, and 3 mL of ammonia (25 wt% NH3) were sequentially added to a beaker and stirred continuously. 0.6 g of resorcinol was weighed and added to the mixture, and stirred thoroughly until the resorcinol was completely dissolved. 0.8 mL of a 37 wt% formaldehyde aqueous solution was added, and stirring was continued for 15 min. Subsequently, 5 mL of tetrapropoxysilane was added, and the mixture was stirred at 30 °C for 24 h. After stirring, the precipitate was collected by centrifugation, and the dried product was a dark brown powder precursor resin silica composite sphere. The collected product was calcined at 600 °C for 2 h under a nitrogen atmosphere, with a heating rate set at 5 °C / min. -1 The pyrolysis products were collected, ground evenly in a mortar, and the powder was transferred to a beaker. 4M sodium hydroxide aqueous solution was added to submerge the powder, and the mixture was stirred at 80°C for 48 hours. The precipitate was collected by centrifugation, washed, and dried to obtain hollow mesoporous carbon spheres.

[0076] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this embodiment differs from that in Example 1 in that the hollow mesoporous carbon spheres used are the hollow mesoporous carbon spheres prepared in this embodiment, while other conditions and parameters are the same as in Example 1.

[0077] Example 11:

[0078] The preparation of hollow mesoporous carbon spheres is the same as in Example 10.

[0079] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this embodiment differs from that in Example 2 in that the hollow mesoporous carbon spheres used are the hollow mesoporous carbon spheres prepared in this embodiment, while other conditions and parameters are the same as in Example 2.

[0080] Example 12:

[0081] The preparation of hollow mesoporous carbon spheres is the same as in Example 10.

[0082] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this embodiment differs from that in Example 3 in that the hollow mesoporous carbon spheres used are the hollow mesoporous carbon spheres prepared in this embodiment, while other conditions and parameters are the same as in Example 3.

[0083] Example 13:

[0084] Preparation of hollow mesoporous carbon spheres: 70 mL of anhydrous ethanol, 10 mL of ultrapure water, and 2 mL of ammonia (25 wt% NH3) were sequentially added to a beaker and stirred continuously. 0.6 g of resorcinol was weighed and added to the mixture, and stirred thoroughly until the resorcinol was completely dissolved. 0.8 mL of a 37 wt% formaldehyde aqueous solution was added, and stirring was continued for 15 min. Subsequently, 5 mL of tetrapropoxysilane was added, and the mixture was stirred at 30 °C for 24 h. After stirring, the precipitate was collected by centrifugation, and the dried product was a dark brown powder precursor resin silica composite sphere. The collected product was calcined at 600 °C for 2 h under a nitrogen atmosphere, with a heating rate set at 5 °C / min. -1 The pyrolysis products were collected, ground evenly in a mortar, and the powder was transferred to a beaker. 4M sodium hydroxide aqueous solution was added to submerge the powder, and the mixture was stirred at 80°C for 48 hours. The precipitate was collected by centrifugation, washed, and dried to obtain hollow mesoporous carbon spheres.

[0085] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this embodiment differs from that in Example 4 in that the hollow mesoporous carbon spheres used are the hollow mesoporous carbon spheres prepared in this embodiment, while other conditions and parameters are the same as in Example 4.

[0086] Example 14:

[0087] The preparation of hollow mesoporous carbon spheres is the same as in Example 13.

[0088] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this embodiment differs from that in Example 5 in that the hollow mesoporous carbon spheres used are the hollow mesoporous carbon spheres prepared in this embodiment, while other conditions and parameters are the same as in Example 5.

[0089] Example 15:

[0090] The preparation of hollow mesoporous carbon spheres is the same as in Example 13.

[0091] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this embodiment differs from that in Example 6 in that the hollow mesoporous carbon spheres used are the hollow mesoporous carbon spheres prepared in this embodiment, while other conditions and parameters are the same as in Example 6.

[0092] Example 16:

[0093] Preparation of hollow mesoporous carbon spheres: 70 mL of anhydrous ethanol, 10 mL of ultrapure water, and 1 mL of ammonia (25 wt% NH3) were sequentially added to a beaker and stirred continuously. 0.6 g of resorcinol was weighed and added to the mixture, and stirred thoroughly until the resorcinol was completely dissolved. 0.8 mL of a 37 wt% formaldehyde aqueous solution was added, and stirring was continued for 15 min. Subsequently, 5 mL of tetrapropoxysilane was added, and the mixture was stirred at 30 °C for 24 h. After stirring, the precipitate was collected by centrifugation, and the dried product was a dark brown powder precursor resin silica composite sphere. The collected product was calcined at 600 °C for 2 h under a nitrogen atmosphere, with a heating rate set at 5 °C / min. -1 The pyrolysis products were collected, ground evenly in a mortar, and the powder was transferred to a beaker. 4M sodium hydroxide aqueous solution was added to submerge the powder, and the mixture was stirred at 80°C for 48 hours. The precipitate was collected by centrifugation, washed, and dried to obtain hollow mesoporous carbon spheres.

[0094] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this embodiment differs from that in Example 7 in that the hollow mesoporous carbon spheres used are the hollow mesoporous carbon spheres prepared in this embodiment, while other conditions and parameters are the same as in Example 7.

[0095] Example 17:

[0096] The preparation of hollow mesoporous carbon spheres is the same as in Example 16.

[0097] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this embodiment differs from that in Example 8 in that the hollow mesoporous carbon spheres used are the hollow mesoporous carbon spheres prepared in this embodiment, while other conditions and parameters are the same as in Example 8.

[0098] Example 18:

[0099] The preparation of hollow mesoporous carbon spheres is the same as in Example 16.

[0100] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this embodiment differs from that in Example 9 in that the hollow mesoporous carbon spheres used are the hollow mesoporous carbon spheres prepared in this embodiment, while other conditions and parameters are the same as in Example 9.

[0101] Comparative Example 1:

[0102] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this comparative example differs from that in Example 1 in that the porous carbon used in this comparative example is acetylene black, while other conditions and parameters are the same as in Example 1.

[0103] Comparative Example 2:

[0104] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this comparative example differs from that in Example 2 in that the porous carbon used in this comparative example is acetylene black, while other conditions and parameters are the same as in Example 2.

[0105] Comparative Example 3:

[0106] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this comparative example differs from that in Example 3 in that the porous carbon used in this comparative example is acetylene black, while other conditions and parameters are the same as in Example 3.

[0107] Comparative Example 4:

[0108] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this comparative example differs from that in Example 4 in that the porous carbon used in this comparative example is Super P, while other conditions and parameters are the same as in Example 4.

[0109] Comparative Example 5:

[0110] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this comparative example differs from that in Example 5 in that the porous carbon used in this comparative example is Super P, while other conditions and parameters are the same as in Example 5.

[0111] Comparative Example 6:

[0112] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this comparative example differs from that in Example 6 in that the porous carbon used in this comparative example is Super P, while other conditions and parameters are the same as in Example 6.

[0113] Comparative Example 7:

[0114] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this comparative example differs from that in Example 7 in that the porous carbon used in this comparative example is Ketjen Black, while other conditions and parameters are the same as in Example 7.

[0115] Comparative Example 8:

[0116] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this comparative example differs from that in Example 8 in that the porous carbon used in this comparative example is Ketjen Black, while other conditions and parameters are the same as in Example 8.

[0117] Comparative Example 9:

[0118] Preparation of composite sulfur cathode: The preparation of composite sulfur cathode in this comparative example differs from that in Example 9 in that the porous carbon used in this comparative example is Ketjen Black, while other conditions and parameters are the same as in Example 9.

[0119] Figures 1-6The images are SEM images of the hollow mesoporous carbon spheres prepared in Examples 1, 4, 7, 10, 13, and 16, respectively. As can be seen from the images, the samples exhibit different morphological structures and particle sizes, and the surface has abundant pores.

[0120] Figure 7 This is a graph showing the isothermal nitrogen adsorption-desorption test results of the hollow mesoporous carbon spheres prepared in Example 1. The specific surface area of ​​this sample is 948 m². 2 g -1 The average pore size is 9 nm, and the total pore volume is 2.233 cm³. 3 g -1 .

[0121] Figures 8-11 The graphs show the charge-discharge measurement results of all-solid-state lithium-sulfur batteries assembled with composite sulfur cathodes prepared in Examples 1, 4, 7, and Comparative Example 1, respectively. As can be seen from the graphs, at a sulfur loading of 4.5 mg / cm³... -2 Under conditions of a current density of 0.1C and a temperature of 60℃, the discharge capacity of the assembled battery is 1208.2 mAh g, respectively. -1 987mAhg -1 938.8mAhg -1 and 815.2mAhg -1 The all-solid-state lithium-sulfur batteries assembled with composite sulfur cathodes prepared in Examples 1, 4, and 7 achieved higher energy density.

[0122] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing a composite sulfur cathode, characterized in that, Include: S1, Preparation of sulfide solid electrolyte precursors in a liquid phase system; S2, add hollow mesoporous carbon spheres to the precursor liquid phase system, mechanically stir, remove solvent, and obtain a mixture powder of sulfide solid electrolyte precursor and hollow mesoporous carbon spheres. S3, the mixture powder is sintered, and elemental sulfur is loaded onto the sintered product to obtain a composite sulfur cathode.

2. The method for preparing a composite sulfur cathode according to claim 1, characterized in that, In step S1, the solvent used in the liquid phase system includes at least one of anhydrous ethanol, ethylenediamine, acetonitrile, ethylene glycol dimethyl ether, N-methylpyrrolidone, diethyl ether, diethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl formate, methyl acetate, ethyl acetate, ethylene carbonate, methyl ethyl carbonate, n-hexane, cyclohexane, and n-heptane.

3. The method for preparing a composite sulfur cathode according to claim 1, characterized in that, In step S1, the sulfide solid electrolyte is an Argyrodite type electrolyte with the chemical formula Li. 7-a PS 6-a X a Where a ranges from 0.5 to 1.5; X is one or more of Cl, Br, and I elements, and its room temperature ionic conductivity is not less than 1 × 10⁻⁶. -4 S / cm.

4. The method for preparing a composite sulfur cathode according to claim 1, characterized in that, In step S2, the hollow mesoporous carbon spheres have a particle size of 200 nm to 700 nm and a specific surface area of ​​800 m². 2 g -1 ~1100m 2 g -1 The average pore size is 5nm to 15nm, and the total pore volume is 2cm³. 3 g -1 ~3.5cm 3 g -1 .

5. The method for preparing a composite sulfur cathode according to claim 1, characterized in that, In step S2, the method for preparing the hollow mesoporous carbon spheres includes the following steps: (1) Resorcinol, formaldehyde and tetrapropoxysilane are added to a mixed solvent composed of water, anhydrous ethanol and ammonia. The mixture is mechanically stirred at a rate of 300 rpm to 1500 rpm for 6 h to 24 h at 30 °C to 50 °C in an air atmosphere. Then the mixture is centrifuged and dried to obtain a resin silica composite ball precursor. The mass ratio of resorcinol to formaldehyde is 0.5:1 to 5:1, and the mass ratio of tetrapropoxysilane to resorcinol is 5:1 to 10:

1. (2) The resin silica composite balls obtained in step (1) are heated to 400℃~900℃ at a heating rate of 0.5℃ / min~5℃ / min under an inert atmosphere and kept at the temperature for 1h~5h to obtain carbon / silica composite. (3) The carbon / silica composite obtained in step (2) is placed in hydrofluoric acid or sodium hydroxide solution and stirred and etched at 30℃~80℃ for 6h~48h. Then, it is centrifuged, washed and dried to obtain the hollow mesoporous carbon spheres.

6. The preparation method according to claim 1, characterized in that, In step S3, the sintering is carried out under an inert atmosphere, the sintering temperature is 300℃~550℃, the sintering time is 5h~20h, and the heating and cooling rate is 0.5℃ / min~5℃ / min.

7. The preparation method according to claim 1, characterized in that, In step S3, the loaded elemental sulfur is subjected to heat treatment at a temperature of 100℃ to 200℃ for a duration of 6h to 48h.

8. The preparation method according to claim 1, characterized in that, The solvent removal method described in step S2 is at least one of centrifugation and evaporation; The centrifugation process involved a speed of 7000 rpm to 11000 rpm and a time of 2 min to 4 min. The solvent evaporation process is carried out at a temperature of 130℃ to 180℃ for a time of 6 hours to 48 hours.

9. The method for preparing a composite sulfur cathode according to claim 1, characterized in that, The mass ratio of the sulfide solid electrolyte, hollow mesoporous carbon spheres, and elemental sulfur in the composite sulfur cathode is one of 10:6:9, 10:3:7, and 20:3:

27.

10. An all-solid-state battery, characterized in that, The composite sulfur cathode prepared by any one of the preparation methods described in claims 1 to 9.

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