Diphenyl disulfide / vesicle carbon composite material as well as preparation method and application thereof

Abstract

The invention discloses a diphenyl disulfide / vesicle carbon composite material as well as a preparation method and application thereof, and relates to the technical field of new energy storage materials. Sodium bicarbonate, potassium hydroxide and methyl cellulose are used as raw materials to prepare vesicle carbon, the vesicle carbon is mixed with diphenyl disulfide, and the mixture is heated in vacuum and inert atmosphere for melt diffusion to obtain the diphenyl disulfide / vesicle carbon composite material. Wherein the adsorption effect of the large specific surface of the vesicle carbon and the packaging effect of the hollow structure can relieve the dissolution loss of the diphenyl disulfide, and the open and intercommunicated pore structure in the vesicle carbon can realize the rapid transmission of ions and electrons. Therefore, the diphenyl disulfide / vesicle carbon composite material prepared by the invention has excellent aluminum storage performance and cycling stability, and can improve the electrochemical performance of an aluminum ion battery when being used as a positive electrode material of the aluminum ion battery. In addition, the diphenyl disulfide and the vesicle carbon are compounded, so that the synergistic effect on improving the specific discharge capacity of the composite material is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy storage materials, and in particular to a diphenyl disulfide / vesicular carbon composite material and a preparation method and application thereof. Background Art

[0002] In recent years, in order to achieve the coordinated development of economy, energy and environment, it has become crucial to develop a renewable, clean and efficient new energy system. Although renewable clean energy such as solar energy can effectively reduce environmental pollution, ensure sustainable energy supply and alleviate the shortage of conventional energy supply. However, they are easily restricted by environmental, geographical and climatic factors. Therefore, the development of efficient energy storage devices and equipment has received great attention from all walks of life. Aluminum, as a negative electrode material for energy storage and energy conversion, has the advantages of abundant content, high safety and environmental friendliness. In addition, aluminum can undergo three-electron transfer reaction. As an electrode material, it has a high theoretical mass specific capacity (2980 mAh / g) and volume specific capacity (8046 mAh / cm 3 ), it can be seen that aluminum ion battery is a potential high-efficiency energy storage and conversion system with price advantage.

[0003] Due to the slow charge and discharge electrochemical reaction kinetics of the positive electrode material, aluminum ion batteries face problems such as slow charge and discharge rate and low capacity ratio. At the same time, most positive electrode materials have the problem of unstable main structure, which makes the cycle performance of aluminum ion batteries poor. Therefore, it is very necessary to develop positive electrode materials that can match aluminum negative electrodes. At present, organic small molecules such as anthraquinone and polycyclic aromatic hydrocarbons are used as positive electrode materials, and the coordination reaction mechanism can effectively eliminate the problems caused by Al 3+ It can solve the problems caused by the high charge density and has less impact on the environment and can achieve sustainable development. However, due to its small molecular size, it has a high solubility in the electrolyte solution, which leads to the problem of poor cycle stability when organic small molecules are used as positive electrode materials.

[0004] In the prior art, CN115148971A discloses a sulfur-carbon / zinc-doped lithium iron phosphate composite cathode material, comprising a zinc-doped lithium iron phosphate material and a sulfur-carbon material encapsulating the zinc-doped lithium iron phosphate. The sulfur-carbon material is prepared by mixing a carbon source (natural fiber), ethanol, and a sulfur source (diphenyl disulfide) and then annealing the mixture. However, annealing the diphenyl disulfide at 900-1100°C completely decomposes the diphenyl disulfide, resulting in no diphenyl disulfide in the sulfur-carbon material. Therefore, the sulfur-carbon material utilizes only sulfur-doped carbon to restrict the growth of lithium iron phosphate particles, thereby shortening the diffusion distance of lithium ions. CN116885196A discloses a polypyrrole@three-dimensional hollow carbon framework composite material and its use in preparing positive electrode materials for aluminum ion batteries. The three-dimensional hollow carbon framework in the composite material is obtained by mixing a carbon source (methyl cellulose) and a carbon crystal template (sodium bicarbonate) and then carbonizing them. Although the three-dimensional hollow carbon skeleton in this composite material has a continuous and interconnected cavity structure, since no pore-forming agent is used in the preparation process, most organic small molecules can only attach to the surface of the three-dimensional hollow carbon skeleton and cannot enter its interior. When the organic small molecules attached to the surface of the three-dimensional hollow carbon skeleton are used as positive electrode materials for aluminum ion batteries, they will still have high solubility in the electrolyte, resulting in poor cycle stability.

[0005] Therefore, it is necessary to construct a positive electrode material that can be used in aluminum ion batteries based on organic small molecules, avoiding the problem of dissolution and loss of organic small molecules in ionic liquid electrolytes while ensuring that the positive electrode material has good electrochemical properties. Summary of the Invention

[0006] In view of the above-mentioned prior art, the purpose of the present invention is to provide a diphenyl disulfide / vesicular carbon composite material and its preparation method and application. The present invention uses sodium bicarbonate, potassium hydroxide and methyl cellulose as raw materials to prepare vesicular carbon, which is then mixed with diphenyl disulfide, placed in a vacuum and inert atmosphere and heated for melt diffusion, to obtain a diphenyl disulfide / vesicular carbon composite material. Among them, the adsorption effect of the large specific surface area of ​​vesicular carbon and the encapsulation effect of the hollow structure can alleviate the dissolution and loss of diphenyl disulfide, and its internal open and interconnected pore structure can realize the rapid transmission of ions and electrons. Therefore, the diphenyl disulfide / vesicular carbon composite material prepared by the present invention has excellent aluminum storage performance and cycle stability, and its use as a positive electrode material for aluminum ion batteries can improve the electrochemical performance of aluminum ion batteries. In addition, the present invention uses diphenyl disulfide and vesicular carbon compounding to have a synergistic effect in improving the discharge specific capacity of the composite material.

[0007] To achieve the above object, the present invention adopts the following technical solutions: The first aspect of the present invention provides a method for preparing a diphenyl disulfide / vesicular carbon composite material, comprising the following steps: (1) Sodium bicarbonate and potassium hydroxide are mixed and added to a methyl cellulose dispersion, ground and mixed, and then dried to obtain a precursor; the precursor is placed in an inert atmosphere and heated to react, and after the reaction is completed, the precursor is cooled and purified to obtain vesicular carbon; (2) Diphenyl disulfide and vesicular carbon are mixed to obtain a mixture, the mixture is placed in a vacuum and inert atmosphere and heated to react, and the solid after the reaction is collected, which is the diphenyl disulfide / vesicular carbon composite material.

[0008] Preferably, in step (1), the methyl cellulose dispersion is prepared by mixing methyl cellulose and deionized water at a material-liquid ratio of (1.5-2.5) g:6 mL.

[0009] Preferably, in step (1), the mass ratio of methyl cellulose, potassium hydroxide and sodium bicarbonate in the methyl cellulose dispersion is 1: (0.1-0.9): (0.6-5).

[0010] Preferably, in step (1), the grinding time is 3-8 min.

[0011] Preferably, in step (1), the drying method is freeze drying, the freeze drying temperature is -45 to -35°C, and the freeze drying time is 48 hours.

[0012] Preferably, in step (1), the inert atmosphere is an argon atmosphere.

[0013] Preferably, in step (1), the specific operation of heating is: first heating to 200-300°C at a heating rate of 3-5°C / min, and keeping warm for 1-3 hours; then heating to 700-900°C at a heating rate of 3-5°C / min, and keeping warm for 4-6 hours.

[0014] Preferably, in step (1), the purification operation is: washing the cooled solid with deionized water 2-3 times, and then freeze-drying for 48-72 hours.

[0015] Preferably, in step (2), the mass ratio of diphenyl disulfide to vesicular carbon is (1-5):1.

[0016] Preferably, in step (2), the vacuum degree is 0 Pa and the inert atmosphere is an argon atmosphere.

[0017] Preferably, in step (2), the specific operation of heating is: heating to 63-310°C at a heating rate of 2-5°C / min, and keeping the temperature for 6-10 hours.

[0018] The second aspect of the present invention provides a diphenyl disulfide / vesicular carbon composite material prepared by the above preparation method.

[0019] The third aspect of the present invention provides the use of the above-mentioned diphenyl disulfide / vesicular carbon composite material as a positive electrode material for aluminum ion batteries.

[0020] A fourth aspect of the present invention provides an aluminum ion battery comprising a positive electrode material, a negative electrode material, and an electrolyte; The positive electrode material is the above-mentioned diphenyl disulfide / vesicular carbon composite material, and the electrolyte is AlCl3 / 1-ethyl-3-methylimidazolium chloride ionic liquid.

[0021] Beneficial effects of the present invention: 1. The present invention uses sodium bicarbonate, potassium hydroxide, and methylcellulose as raw materials to prepare vesicular carbon. Then, diphenyl disulfide and the vesicular carbon are mixed and heated under vacuum and an inert atmosphere to cause melt diffusion, thereby obtaining a diphenyl disulfide / vesicular carbon composite material. The diphenyl disulfide / vesicular carbon composite material prepared by the present invention has excellent aluminum storage performance and cyclic stability. Specifically, the diphenyl disulfide / vesicular carbon composite material prepared by the present invention has a discharge capacity of 240 mAh / g after 60 cycles, maintaining 82% of the initial discharge capacity, and significantly improving cyclic stability.

[0022] Specifically, the vesicular carbon has an open, interconnected pore structure and a large specific surface area. The adsorption effect (physical adsorption) of the large specific surface area and the encapsulation (spatial confinement) of the hollow structure of the vesicular carbon can mitigate the dissolution and loss of diphenyl disulfide. Furthermore, the open, interconnected pore structure within the vesicular carbon also enables rapid ion and electron transport. Therefore, the diphenyl disulfide / vesicular carbon composite material produced by the present invention has excellent aluminum storage performance and cyclic stability.

[0023] Furthermore, the present invention's combination of diphenyl disulfide and vesicular carbon exhibits a synergistic effect in increasing the composite's specific discharge capacity. Specifically, within a voltage range of 0.1V-2.3V, the vesicular carbon and diphenyl disulfide exhibited specific discharge capacities of 44 mAh / g and 147 mAh / g, respectively, while the diphenyl disulfide / vesicular carbon composite exhibited a specific discharge capacity of 247 mAh / g.

[0024] 2. When preparing vesicular carbon with an open interconnected pore structure, the present invention uses sodium bicarbonate as a template and potassium hydroxide as a pore-forming agent, and prepares porous vesicular carbon by a salt crystal template method. Among them, the amount of pore-forming agent potassium hydroxide will affect the cyclic stability of the diphenyl disulfide / vesicular carbon composite material. When the amount of potassium hydroxide is too little, the number of pores on the vesicular carbon is too small, so that the number of diphenyl disulfide molecules entering the interior of the vesicular carbon is small, thereby making the cyclic stability of the diphenyl disulfide / vesicular carbon composite material poor; when the amount of potassium hydroxide is too much, the number of pores on the vesicular carbon is too much, so that the interconnected pores of the vesicular carbon become an open pore structure, thereby failing to achieve the encapsulation of diphenyl disulfide, affecting the cyclic stability of the diphenyl disulfide / vesicular carbon composite material.

[0025] 3. Diphenyl disulfide forms sulfhydryl radicals, which combine with aluminum radicals in the system to achieve excellent aluminum storage performance. At the same time, the molecular structure of diphenyl disulfide is utilized to control the formation of easily soluble polysulfides, fundamentally suppressing the occurrence of the "shuttle effect" and achieving better cycle stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 : SEM image of the diphenyl disulfide / vesicular carbon composite material prepared in Example 1; Figure 2 : SEM image and EDS Mapping image of the diphenyl disulfide / vesicular carbon composite material prepared in Example 1; wherein, (a) is the SEM image of the diphenyl disulfide / vesicular carbon composite material; (b) is the mapping overlay of the C, O and S elements in the diphenyl disulfide / vesicular carbon composite material; (c) is the EDS Mapping image of the C element in the diphenyl disulfide / vesicular carbon composite material; (d) is the EDS Mapping image of the O element in the diphenyl disulfide / vesicular carbon composite material; (e) is the EDS Mapping image of the S element in the diphenyl disulfide / vesicular carbon composite material; Figure 3 : SEM image of the diphenyl disulfide / vesicular carbon composite material prepared in Comparative Example 1; Figure 4 : SEM image of the diphenyl disulfide / porous carbon composite material prepared in Comparative Example 2; Figure 5 : Cyclic voltammetry test diagram of diphenyl disulfide in Experimental Example 2; Figure 6 : Specific capacity analysis diagram of diphenyl disulfide, vesicular carbon and the diphenyl disulfide / vesicular carbon composite material prepared in Experimental Example 2; Figure 7: Cyclic stability diagrams of different materials in Experimental Example 2; (a) is the cyclic stability diagram of diphenyl disulfide, (b) is the cyclic stability diagram of diphenyl disulfide / vesicular carbon composite material prepared in Example 1, (c) is the cyclic stability diagram of diphenyl disulfide / vesicular carbon composite material prepared in Comparative Example 1, and (d) is the cyclic stability diagram of diphenyl disulfide / porous carbon composite material prepared in Comparative Example 2. DETAILED DESCRIPTION

[0027] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0028] In the existing technology, organic small molecules are used as aluminum ion positive electrode materials, although they can effectively eliminate the 3+ The problem caused by the high charge density, but the organic small molecules have a high solubility in the electrolyte, which leads to the problem of poor cycle stability when the organic small molecules are used as positive electrode materials. The paper "Research on the Application of Small Molecule Organic Disulfides in Liquid Flow Batteries" (Chen Qiliang, Zhengzhou University, May 2023) discloses that the good solubility and highly reversible redox behavior of small molecule diphenyl disulfide in organic electrolytes can be used as an active material for liquid flow batteries. It can be seen that the paper mainly uses the high solubility of diphenyl disulfide for liquid flow batteries, and the property of diphenyl disulfide that it is extremely soluble in organic electrolytes causes it to fall off from the positive electrode and enter the electrolyte when used as a positive electrode material, resulting in the problem of poor cycle stability of the positive electrode material.

[0029] Based on this, this application uses diphenyl disulfide and vesicular carbon as raw materials to prepare a diphenyl disulfide / vesicular carbon composite material, which is used as an aluminum ion positive electrode material to address the poor cycling stability problem of diphenyl disulfide, a small organic molecule, as a positive electrode material. The specific preparation method is: sodium bicarbonate, potassium hydroxide, and methyl cellulose are used as raw materials to prepare the vesicular carbon. Then, after mixing the diphenyl disulfide and vesicular carbon, the mixture is placed in a vacuum and inert atmosphere and heated to cause melt diffusion, thereby obtaining the diphenyl disulfide / vesicular carbon composite material.

[0030] By mixing diphenyl disulfide with vesicular carbon, capillary action can adsorb diphenyl disulfide into the interconnected pores within the vesicular carbon under heating and vacuum conditions. This allows the diphenyl disulfide to be encapsulated within the vesicular structure, reducing its dissolution and shedding during use, thereby improving the cycling stability of the cathode material. The porous vesicular carbon was used as a carrier for diphenyl disulfide to prepare a diphenyl disulfide / vesicular carbon composite. The main purpose is to utilize the semi-enclosed structure of the vesicular carbon to "encapsulate" some diphenyl disulfide within the vesicle structure. Through the spatial confinement of the vesicular carbon, the dissolution and loss of diphenyl disulfide in the electrolyte as an electrode material is alleviated, allowing the diphenyl disulfide / vesicular carbon composite to improve its structural stability when used as an electrode material and extend its cycle life. Furthermore, the open and interconnected pore structure of the porous vesicular carbon provides abundant ion transport channels, which helps improve the transport rate of energy storage active ions when used as an electrode material, resulting in better ionic conductivity and excellent rate performance. In summary, the porous vesicular carbon of the present invention can effectively improve the stability and ionic conductivity of the composite material. Compared with porous vesicular carbon, porous carbons such as porous graphene and porous carbon spheres, when used as carriers to support diphenyl disulfide, mainly stabilize diphenyl disulfide through the carbon's physical adsorption of diphenyl disulfide. Without the spatial confinement effect of the vesicular structure, it cannot effectively improve the dissolution and loss of diphenyl disulfide.

[0031] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0032] The experimental materials used in the examples of the present invention are all conventional experimental materials in the art and can be purchased through commercial channels.

[0033] Example 1: Preparation of diphenyl disulfide / vesicular carbon composite material (1) Add 1 g of methyl cellulose to 3 mL of deionized water and stir until viscous to obtain a methyl cellulose dispersion. Mix 5 g of sodium bicarbonate and 0.5 g of potassium hydroxide and slowly add them to the methyl cellulose dispersion. Grind for 5 min to ensure uniform mixing, then freeze-dry at -40 °C for 48 h to obtain a precursor. The precursor was placed in a tube furnace, in a protective atmosphere of high-purity argon, first ventilated at room temperature for 30 minutes, then heated to 200°C at a heating rate of 4°C / min and sintered at a constant temperature for 2 hours, and then heated to 800°C at a heating rate of 4°C / min and sintered at a constant temperature for 4 hours; after the reaction was completed, the temperature was cooled, and the obtained product was fully washed with deionized water to remove the sodium bicarbonate template, and then placed at -40°C for freeze-drying for 48 hours to obtain vesicular carbon; (2) Grind and mix 50 mg of diphenyl disulfide and 50 mg of vesicular carbon evenly to obtain a mixture; place the mixture in a glass tube, evacuate the glass tube to 0 Pa and then seal it; place the glass tube containing the mixture in a tubular furnace, introduce high-purity argon gas, and slowly increase the temperature to 63°C at a heating rate of 2°C / min, maintain the constant temperature for 10 hours, and remove the glass tube after the tubular furnace temperature naturally cools down to room temperature, and take out the solid sample therein to obtain a diphenyl disulfide / vesicular carbon composite material.

[0034] Example 2: Preparation method of diphenyl disulfide / vesicular carbon composite material (1) Add 1 g of methyl cellulose to 3 mL of deionized water and stir until viscous to obtain a methyl cellulose dispersion. Mix 0.6 g of sodium bicarbonate and 0.1 g of potassium hydroxide and slowly add them to the methyl cellulose dispersion. Grind for 3 minutes to mix evenly, and then freeze-dry at -45 °C for 48 hours to obtain a precursor. The precursor was placed in a tube furnace, in a protective atmosphere of high-purity argon, first ventilated at room temperature for 30 minutes, then heated to 250°C at a heating rate of 3°C / min and sintered at a constant temperature for 1 hour, and then heated to 700°C at a heating rate of 3°C / min and sintered at a constant temperature for 5 hours; after the reaction was completed, the temperature was cooled, and the obtained product was fully washed with deionized water to remove the sodium bicarbonate template, and then placed at -45°C for freeze-drying for 48 hours to obtain vesicular carbon; (2) Grind and mix 150 mg of diphenyl disulfide and 50 mg of vesicular carbon evenly to obtain a mixture; place the mixture in a glass tube, evacuate the glass tube to 0 Pa and then seal it; place the glass tube containing the mixture in a tubular furnace, introduce high-purity argon gas, and slowly increase the temperature to 168°C at a heating rate of 4°C / min, maintain the constant temperature for 6 hours, and remove the glass tube after the tubular furnace temperature naturally cools down to room temperature, and take out the solid sample therein to obtain a diphenyl disulfide / vesicular carbon composite material.

[0035] Example 3: Preparation method of diphenyl disulfide / vesicular carbon composite material (1) Add 1 g of methyl cellulose to 3 mL of deionized water and stir until viscous to obtain a methyl cellulose dispersion. Mix 2.6 g of sodium bicarbonate and 0.9 g of potassium hydroxide and slowly add them to the methyl cellulose dispersion. Grind for 8 minutes to mix until uniform, and then freeze-dry at -35 °C for 48 hours to obtain a precursor. The precursor was placed in a tube furnace, in a protective atmosphere of high-purity argon, first ventilated at room temperature for 30 minutes, then heated to 300°C at a heating rate of 5°C / min and sintered at a constant temperature for 3 hours, and then heated to 900°C at a heating rate of 5°C / min and sintered at a constant temperature for 6 hours; after the reaction was completed, the temperature was cooled, and the obtained product was fully washed with deionized water to remove the sodium bicarbonate template, and then placed at -35°C for freeze-drying for 48 hours to obtain vesicular carbon; (2) Grind and mix 250 mg of diphenyl disulfide and 50 mg of vesicular carbon evenly to obtain a mixture; place the mixture in a glass tube, evacuate the glass tube to 0 Pa and then seal it; place the glass tube containing the mixture in a tubular furnace, introduce high-purity argon gas, and slowly increase the temperature to 310°C at a heating rate of 5°C / min, maintain the constant temperature for 10 hours, and remove the glass tube after the tubular furnace temperature naturally cools down to room temperature, and take out the solid sample therein to obtain a diphenyl disulfide / vesicular carbon composite material.

[0036] Comparative Example 1: Preparation method of diphenyl disulfide / vesicular carbon composite material The difference between this comparative example and Example 1 is that the mass ratio of potassium hydroxide to methyl cellulose is 0.08:1. The specific steps are: 1 g of methyl cellulose was added to 3 mL of deionized water and stirred until viscous to obtain a methyl cellulose dispersion; 5 g of sodium bicarbonate and 0.08 g of potassium hydroxide were mixed and slowly added to the methyl cellulose dispersion and stirred evenly; the mixture was freeze-dried to obtain a precursor; the precursor was placed in a tube furnace, and in a protective atmosphere of high-purity argon, it was first ventilated at room temperature for 30 minutes, then sintered at a constant temperature of 200°C for 2 hours, and then sintered at a constant temperature of 800°C for 4 hours; after the reaction was completed, the temperature was lowered, and the resulting product was thoroughly washed with deionized water to remove the sodium bicarbonate template, and then placed in a freeze dryer and dried for 48 hours to obtain vesicular carbon; then the vesicular carbon and diphenyl disulfide were mixed and melt-diffused according to the method of Example 1 to obtain a diphenyl disulfide / vesicular carbon composite material.

[0037] Comparative Example 2: Preparation method of diphenyl disulfide / porous carbon composite material The difference between this comparative example and Example 1 is that the mass ratio of potassium hydroxide to methyl cellulose is 1:1. The specific steps are: 1 g of methyl cellulose was added to 3 mL of deionized water and stirred until it became viscous to obtain a methyl cellulose dispersion; 5 g of sodium bicarbonate and 1 g of potassium hydroxide were mixed and slowly added to the methyl cellulose dispersion and stirred evenly; the mixture was freeze-dried to obtain a precursor; the precursor was placed in a tube furnace, and in a protective atmosphere of high-purity argon, it was first ventilated at room temperature for 30 minutes, and then sintered at a constant temperature of 200°C for 2 hours, and then sintered at a constant temperature of 800°C for 4 hours; after the reaction was completed, the temperature was lowered, and the obtained product was fully washed with deionized water to remove the sodium bicarbonate template, and then placed in a freeze dryer and dried for 48 hours to obtain porous carbon; then the porous carbon and diphenyl disulfide were mixed and melt-diffused according to the method of Example 1 to obtain a diphenyl disulfide / porous carbon composite material.

[0038] Experimental Example 1: Structural Characterization 1. The diphenyl disulfide / capsule carbon composite material prepared in Example 1 was subjected to electron microscopy analysis and EDS mapping analysis. The results are as follows: Figure 1 and Figure 2 shown.

[0039] Depend on Figure 1 It can be seen that the diphenyl disulfide / vesicular carbon composite material prepared in Example 1 not only retains the three-dimensional vesicular structure of the vesicular carbon, but also ensures that diphenyl disulfide is loaded on the surface and vesicular structure of the vesicular carbon. Figure 2 It can be found that the S element in the diphenyl disulfide structure is relatively evenly loaded on the vesicular carbon, proving the successful preparation of diphenyl disulfide / vesicular carbon composite materials.

[0040] 2. The composite material obtained in Comparative Example 1-2 was analyzed by electron microscopy. The results are as follows: Figure 3-Figure 4 shown.

[0041] pass Figure 3 It can be found that when the amount of KOH is too small, the prepared diphenyl disulfide / vesicular carbon composite material retains the three-dimensional vesicular structure of the vesicular carbon, but the diphenyl disulfide is mostly loaded on the surface of the vesicular carbon, and there is very little diphenyl disulfide inside the vesicular carbon. Figure 4 It can be seen that when the amount of KOH is too much, the porous carbon in the prepared diphenyl disulfide / porous carbon composite material presents an open pore structure, and the open interconnected pore structure inside the vesicular carbon is not well retained.

[0042] Test Example 2: Electrochemical Properties Diphenyl disulfide, the vesicular carbon prepared in step (1) of Example 1, the diphenyl disulfide / vesicular carbon composite material prepared in Example 1, and the composite material prepared in Comparative Examples 1-2 were used as active materials to prepare electrode sheets, and aluminum ion batteries were constructed to test the electrochemical performance and cycle stability. The details are as follows: (1) Weigh 16 mg of active material, mix it with 2 mg of acetylene black and 2 mg of polyvinylidene fluoride, and grind it for 30 minutes to obtain a mixture. Add the mixture to 800 μL of N-methylpyrrolidone and ultrasonically disperse it for 2 hours to obtain a dispersion. Use carbon paper prepared from carbon nanotubes as a current collector, measure 50 μL of the dispersion droplet and apply it on the carbon paper, and place it at 60°C for vacuum drying for 12 hours to obtain an electrode sheet. (2) assembling a battery using a Swagelok battery mold, using the electrode sheet prepared in step (1) as the positive electrode sheet, high-purity aluminum foil as the negative electrode sheet, glass fiber film as the separator, and AlCl3 / 1-ethyl-3-methylimidazolium chloride ionic liquid as the electrolyte to assemble an aluminum ion battery; (3) The assembled aluminum ion battery was placed on a Shanghai Chenhua CHI660D electrochemical workstation and a LANHE CT2001A battery charge and discharge instrument for electrochemical performance testing. During the test, the CV test parameters were set to: a voltage range of 0.1-2.3V; the constant current charge and discharge test parameters were set to: a voltage range of 0.1-2.3V and a current density of 100-500mA / g. The results are as follows. Figure 5 and Figure 6 shown.

[0043] from Figure 5 It can be seen that a reversible redox reaction occurs during the charge and discharge process of the battery, and a stable redox peak appears at 1.32 V-1.17 V. Figure 6 It can be seen that under the same test conditions, the discharge specific capacities of vesicular carbon and diphenyl disulfide are 44 mAh / g and 147 mAh / g, respectively, while the discharge specific capacity of the diphenyl disulfide / vesicular carbon composite is 247 mAh / g. The reason is that the addition of vesicular carbon not only alleviates the dissolution and loss of diphenyl disulfide in the electrolyte, but also improves the effective utilization rate of diphenyl disulfide electrode active materials to a certain extent, thereby further improving the specific capacity of the composite material. Therefore, diphenyl disulfide and vesicular carbon have a synergistic effect in improving the discharge specific capacity of the composite material.

[0044] Figure 7 The cycling stability test results of electrodes of different materials are shown in Table 1. Figure 7It can be seen that after the same number of cycles, the discharge capacity of the diphenyl disulfide electrode after 60 cycles is 91 mAh / g, and the capacity retention rate is only 13% of the initial capacity; while the discharge capacity of the diphenyl disulfide / vesicle carbon composite material electrode after 60 cycles can still be maintained at about 240 mAh / g, maintaining 82% of the initial discharge capacity, and the electrode stability is significantly improved compared to the diphenyl disulfide electrode. At the same time, after the same number of cycles of 60, the diphenyl disulfide / vesicle carbon composite material electrode prepared in Comparative Example 1 and the diphenyl disulfide / porous carbon composite material electrode prepared in Comparative Example 2 have capacities of 138 mAh / g and 133 mAh / g, respectively. Relative to the initial discharge capacity, the capacity retention rates are 38% and 43%, respectively. Compared with the diphenyl disulfide / vesicle carbon composite material electrode prepared in Example 1, its improvement in battery cycle performance is limited.

[0045] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a diphenyl disulfide / vesicular carbon composite material, characterized in that: The following steps are involved: (1) Sodium bicarbonate and potassium hydroxide are mixed and added to a methyl cellulose dispersion, ground and mixed, and then dried to obtain a precursor; the precursor is placed in an inert atmosphere and heated to react, and after the reaction is completed, the precursor is cooled and purified to obtain vesicular carbon; (2) Diphenyl disulfide and vesicular carbon are mixed to obtain a mixture, the mixture is placed in a vacuum and inert atmosphere and heated to react, and the solid after the reaction is collected, which is the diphenyl disulfide / vesicular carbon composite material.

2. The method for preparing the diphenyl disulfide / vesicular carbon composite material according to claim 1, wherein: In step (1), the mass ratio of methyl cellulose, potassium hydroxide and sodium bicarbonate in the methyl cellulose dispersion is 1: (0.1-0.9): (0.6-5).

3. The method for preparing the diphenyl disulfide / vesicular carbon composite material according to claim 1, wherein: In step (1), the methyl cellulose dispersion is prepared by mixing methyl cellulose and deionized water at a material-liquid ratio of (1.5-2.5) g:6 mL.

4. The method for preparing the diphenyl disulfide / vesicular carbon composite material according to claim 1, wherein: In step (1), the grinding time is 3-8 minutes; the drying method is freeze drying, the freeze drying temperature is -45 to -35°C, and the freeze drying time is 48 hours.

5. The method for preparing the diphenyl disulfide / vesicular carbon composite material according to claim 1, wherein: In step (1), the inert atmosphere is an argon atmosphere, and the specific heating operation is: first, heating to 200-300°C at a heating rate of 3-5°C / min, and keeping warm for 1-3 hours; then heating to 700-900°C at a heating rate of 3-5°C / min, and keeping warm for 4-6 hours.

6. The method for preparing the diphenyl disulfide / vesicular carbon composite material according to claim 1, wherein: In step (2), the mass ratio of diphenyl disulfide to vesicular carbon is (1-5):

1.

7. The method for preparing the diphenyl disulfide / vesicular carbon composite material according to claim 1, wherein: In step (2), the vacuum degree is 0 Pa and the inert atmosphere is an argon atmosphere.

8. The method for preparing the diphenyl disulfide / vesicular carbon composite material according to claim 1, wherein: In step (2), the specific operation of heating is: heating to 63-310°C at a heating rate of 2-5°C / min, and keeping the temperature for 6-10 hours.

9. The diphenyl disulfide / vesicular carbon composite material prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the diphenyl disulfide / vesicular carbon composite material according to claim 9 as a positive electrode material for aluminum ion batteries.

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