A diphenyl disulfide / vesicular carbon composite material, a preparation method and application thereof

Abstract

The application discloses a diphenyl disulfide / vesicle carbon composite material and a preparation method and application thereof, and relates to the technical field of new energy storage materials.The vesicle carbon is prepared by using sodium bicarbonate, potassium hydroxide and methyl cellulose as raw materials, and then the vesicle carbon is mixed with diphenyl disulfide and heated under vacuum and inert atmosphere for melt diffusion, so that the diphenyl disulfide / vesicle carbon composite material is obtained.In the application, the adsorption of the large specific surface of the vesicle carbon and the encapsulation of the hollow structure can alleviate the loss of the diphenyl disulfide, and the open and interconnected 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 application has excellent aluminum storage performance and cycle stability, and when the material is used as a positive electrode material of an aluminum ion battery, the electrochemical performance of the aluminum ion battery can be improved.In addition, the diphenyl disulfide and the vesicle carbon have a synergistic effect on improving the specific discharge capacity of the composite material.

Description

TECHNICAL FIELD

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

[0002] In recent years, to realize the coordinated development of economy, energy and environment, it is essential to develop renewable, clean and efficient new energy systems. Although renewable clean energy such as solar energy can effectively reduce environmental pollution, ensure sustainable supply of energy and alleviate the shortage of conventional energy supply. However, they are easily affected by environmental, geographical and climatic factors. Therefore, the development of efficient energy storage devices and equipment has been highly valued by all sectors of society. As an energy storage and energy conversion anode material, aluminum has the advantages of abundant content, high safety and environmental friendliness. Moreover, aluminum can undergo a three-electron transfer reaction, and as an electrode material has a high theoretical mass specific capacity (2980 mAh / g) and volume specific capacity (8046 mAh / cm 3 ), Therefore, aluminum ion battery is a potential high-efficiency energy storage and conversion system with price advantage.

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

[0004] In the prior art, CN115148971A discloses a sulfur-carbon / zinc-doped lithium iron phosphate composite positive electrode material, which comprises a zinc-doped lithium iron phosphate material and a sulfur-carbon material wrapped outside the zinc-doped lithium iron phosphate material. The preparation method of the sulfur-carbon material is as follows: a carbon source (natural fiber), ethanol and a sulfur source (diphenyl disulfide) are mixed and then annealed to obtain the sulfur-carbon material. However, annealing diphenyl disulfide at 900-1100 DEG C will completely decompose the diphenyl disulfide, so that the diphenyl disulfide does not exist in the sulfur-carbon material. Therefore, the sulfur-carbon material only uses sulfur-doped carbon to limit the growth of lithium iron phosphate particles, thereby shortening the diffusion distance of lithium ions. CN116885196A discloses a polypyrrole / three-dimensional cavity carbon skeleton composite material and its application in preparing an aluminum ion battery positive electrode material. The three-dimensional cavity carbon skeleton in the composite material is obtained by mixing a carbon source (methyl cellulose) and a carbon crystal template agent (sodium bicarbonate) and then performing carbonization treatment. Although the three-dimensional cavity carbon skeleton in the composite material has a continuous and interconnected cavity structure, since no pore-forming agent is used in the preparation process, most of the organic small molecules can only be attached to the surface of the three-dimensional cavity carbon skeleton and cannot enter the inside of the three-dimensional cavity carbon skeleton. When the organic small molecules attached to the surface of the three-dimensional cavity carbon skeleton are used as aluminum ion battery positive electrode materials, they still have high solubility in electrolyte, thereby causing poor cycle stability.

[0005] Therefore, it is necessary to construct a positive electrode material for an aluminum ion battery based on an organic small molecule, avoid the problem of loss of the organic small molecule due to dissolution in an ionic liquid electrolyte, and ensure that the positive electrode material has good electrochemical performance. SUMMARY

[0006] In view of the above prior art, the purpose of the present application is to provide a diphenyl disulfide / vesicular carbon composite material, a preparation method and application thereof. The present application uses sodium bicarbonate, potassium hydroxide and methyl cellulose as raw materials to prepare vesicular carbon, and then mixes the vesicular carbon with diphenyl disulfide and heats it under vacuum and inert atmosphere to perform melt diffusion, thereby obtaining the diphenyl disulfide / vesicular carbon composite material. The large specific surface area of the vesicular carbon and the encapsulation effect of the hollow structure can alleviate the loss of diphenyl disulfide due to dissolution, and the open and interconnected pore structure in the interior can realize the rapid transmission of ions and electrons. Therefore, the diphenyl disulfide / vesicular carbon composite material prepared by the present application has excellent aluminum storage performance and cycle stability, and when used as a positive electrode material for an aluminum ion battery, it can improve the electrochemical performance of the aluminum ion battery. In addition, the present application uses diphenyl disulfide and vesicular carbon in combination to have a synergistic effect on improving the discharge specific capacity of the composite material.

[0007] To achieve the above purpose, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a method for preparing a diphenyl disulfide / vesicular carbon composite material, comprising the following steps:

[0009] (1) mixing sodium bicarbonate and potassium hydroxide, and then adding them into a methyl cellulose dispersion solution, grinding and mixing uniformly, and drying to obtain a precursor; placing the precursor in an inert atmosphere, heating and reacting, after the reaction is completed, cooling and purifying to obtain vesicular carbon;

[0010] (2) mixing diphenyl disulfide and vesicular carbon uniformly to obtain a mixture, and placing the mixture in a vacuum and inert atmosphere, heating and reacting, and collecting the solid after the reaction, to obtain a diphenyl disulfide / vesicular carbon composite material.

[0011] Preferably, in step (1), the methyl cellulose dispersion solution is prepared by mixing methyl cellulose and deionized water at a liquid ratio of (1.5-2.5) g:6 mL.

[0012] Preferably, in step (1), the mass ratio of methyl cellulose, potassium hydroxide and sodium bicarbonate in the methyl cellulose dispersion solution is 1:(0.1-0.9):(0.6-5).

[0013] Preferably, in step (1), the grinding time is 3-8 min.

[0014] Preferably, in step (1), the drying method is freeze-drying, the freeze-drying temperature is -45~-35℃, and the freeze-drying time is 48 h.

[0015] Preferably, in step (1), the inert atmosphere is an argon atmosphere.

[0016] Preferably, in step (1), the heating operation is as follows: first, heating at a temperature rising rate of 3-5℃ / min to 200-300℃, and holding for 1-3 h; then, heating at a temperature rising rate of 3-5℃ / min to 700-900℃, and holding for 4-6 h.

[0017] Preferably, in step (1), the purification operation is as follows: washing the cooled solid with deionized water for 2-3 times, and freeze-drying for 48-72 h.

[0018] Preferably, in step (2), the mass ratio of diphenyl disulfide and vesicular carbon is (1-5):1.

[0019] Preferably, in step (2), the vacuum degree is 0 Pa, and the inert atmosphere is an argon atmosphere.

[0020] Preferably, in step (2), the heating operation is as follows: heating at a temperature rising rate of 2-5℃ / min to 63-310℃, and holding for 6-10 h.

[0021] In a second aspect, the application provides a diphenyl disulfide / vacuole carbon composite material prepared by the preparation method.

[0022] In a third aspect, the application provides the use of the diphenyl disulfide / vacuole carbon composite material as a positive electrode material of an aluminum ion battery.

[0023] In a fourth aspect, the application provides an aluminum ion battery comprising a positive electrode material, a negative electrode material and an electrolyte.

[0024] The positive electrode material is the diphenyl disulfide / vacuole carbon composite material, and the electrolyte is AlCl3 / 1-ethyl-3-methylimidazolium chloride ionic liquid.

[0025] The application has the following advantages:

[0026] 1. The application uses sodium bicarbonate, potassium hydroxide and methyl cellulose as raw materials to prepare vacuole carbon, and then diphenyl disulfide and the vacuole carbon are mixed and heated under vacuum and inert atmosphere for melt diffusion to obtain a diphenyl disulfide / vacuole carbon composite material. The diphenyl disulfide / vacuole carbon composite material prepared by the application has excellent aluminum storage performance and cycle stability. Specifically, the diphenyl disulfide / vacuole carbon composite material prepared by the application has a discharge specific capacity of 240 mAh / g after 60 cycles, and can maintain 82% of the initial discharge specific capacity, and the cycle stability is greatly improved.

[0027] Specifically, the vacuole carbon has an open and interconnected pore structure and a large specific surface area. The adsorption effect (physical adsorption) of the large specific surface of the vacuole carbon and the packaging effect (spatial confinement) of the hollow structure can alleviate the loss of diphenyl disulfide. In addition, the open and interconnected pore structure inside the vacuole carbon can also realize the rapid transmission of ions and electrons. Therefore, the diphenyl disulfide / vacuole carbon composite material prepared by the application has excellent aluminum storage performance and cycle stability.

[0028] In addition, the use of diphenyl disulfide and vacuole carbon in the application has a synergistic effect on improving the discharge specific capacity of the composite material. Specifically, in the voltage range of 0.1V-2.3V, the discharge specific capacity of the vacuole carbon and the diphenyl disulfide is 44mAh / g and 147 mAh / g, respectively, and the discharge specific capacity of the diphenyl disulfide / vacuole carbon composite material is 247 mAh / g.

[0029] 2. When the vesicular carbon with open interpenetrating pore structure is prepared according to the present application, sodium bicarbonate is used as a template agent, and potassium hydroxide is used as a pore-forming agent, and the porous vesicular carbon is prepared by a salt crystal template method. The amount of the pore-forming agent potassium hydroxide will affect the cycle stability of the diphenyl disulfide / vesicular carbon composite material. When the amount of potassium hydroxide is too small, the number of pores on the vesicular carbon is too small, so that the number of diphenyl disulfide molecules entering the inside of the vesicular carbon is small, thereby making the cycle stability of the diphenyl disulfide / vesicular carbon composite material poor. When the amount of potassium hydroxide is too large, the number of pores on the vesicular carbon is too large, thereby making the interpenetrating pores of the vesicular carbon become open pore structure, so that the encapsulation of diphenyl disulfide cannot be realized, and the cycle stability of the diphenyl disulfide / vesicular carbon composite material is affected.

[0030] 3. Diphenyl disulfide forms a sulfur-based free radical, which combines with an aluminum-based free radical in the system to achieve good aluminum storage performance. At the same time, the molecular structure characteristics of diphenyl disulfide are used to control the generation of easily soluble polysulfides, thereby fundamentally inhibiting the occurrence of "shuttle effect", and good cycle stability is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 SEM image of the diphenyl disulfide / vesicular carbon composite material prepared in Example 1;

[0032] 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 superimposed image of C, O and S elements in the diphenyl disulfide / vesicular carbon composite material; (c) is the EDS Mapping image of C element in the diphenyl disulfide / vesicular carbon composite material; (d) is the EDS Mapping image of O element in the diphenyl disulfide / vesicular carbon composite material; (e) is the EDS Mapping image of S element in the diphenyl disulfide / vesicular carbon composite material;

[0033] Figure 3 SEM image of the diphenyl disulfide / vesicular carbon composite material prepared in Comparative Example 1;

[0034] Figure 4 SEM image of the diphenyl disulfide / vesicular carbon composite material prepared in Comparative Example 2;

[0035] Figure 5 Cyclic voltammetry test image of diphenyl disulfide in Test Example 2;

[0036] Figure 6 Specific capacity analysis image of diphenyl disulfide, vesicular carbon and the diphenyl disulfide / vesicular carbon composite material prepared in Example 1 in Test Example 2;

[0037] Figure 7 : Cycle stability plots of different materials in Test Example 2; (a) is a cycle stability plot of diphenyl disulfide, (b) is a cycle stability plot of diphenyl disulfide / vesicular carbon composite material prepared in Example 1, (c) is a cycle stability plot of diphenyl disulfide / vesicular carbon composite material prepared in Comparative Example 1, and (d) is a cycle stability plot of diphenyl disulfide / porous carbon composite material prepared in Comparative Example 2. DETAILED DESCRIPTION

[0038] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0039] In the prior art, although the use of organic small molecules as aluminum ion positive electrode materials can effectively eliminate the problems caused by the high charge density of Al 3+ , the organic small molecules have a high solubility in electrolyte, which leads to the problem of poor cycle stability when used as a positive electrode material. The paper "Application Research of Small Molecule Organic Disulfide in Flow Battery" (Chen Qiliang, Zhengzhou University, May 2023) discloses the use of small molecule diphenyl disulfide in organic electrolyte for its good solubility and highly reversible redox behavior, which can be used as an active material for flow batteries. As can be seen, the high solubility of diphenyl disulfide is mainly used in flow batteries in the paper, and the property of diphenyl disulfide that is easily dissolved in organic electrolyte makes it fall off from the positive electrode into the electrolyte when used as a positive electrode material, which leads to the problem of poor cycle stability of the positive electrode material.

[0040] Based on this, diphenyl disulfide and vesicular carbon are used as raw materials to prepare a diphenyl disulfide / vesicular carbon composite material in the present application, which is used as an aluminum ion positive electrode material to solve the problem of poor cycle stability of diphenyl disulfide as a positive electrode material. The specific preparation method is as follows: sodium bicarbonate, potassium hydroxide and methyl cellulose are used as raw materials to prepare vesicular carbon, then diphenyl disulfide and vesicular carbon are mixed, heated under vacuum and inert atmosphere for melt diffusion, and a diphenyl disulfide / vesicular carbon composite material is obtained.

[0041] Diphenyl disulfide and vesicular carbon are mixed, and diphenyl disulfide is adsorbed into the interconnected pores inside the vesicular carbon under the conditions of heating and vacuum by capillary action, so that the diphenyl disulfide is encapsulated inside the vesicular structure to reduce the dissolution and shedding of the diphenyl disulfide during use, thereby improving the cycle stability of the positive electrode material. The porous vesicular carbon is used as a carrier of diphenyl disulfide to prepare a diphenyl disulfide / vesicular carbon composite material. The main purpose is that, on the one hand, the semi-closed structure of the vesicular carbon encapsulates part of the diphenyl disulfide into the vesicular structure, and the space confinement effect of the vesicular carbon alleviates the dissolution and loss of the diphenyl disulfide as an electrode material in the electrolyte, so that the diphenyl disulfide / vesicular carbon can improve the structural stability of the composite material as an electrode material and prolong the cycle life thereof; on the other hand, the open and interconnected pore structure of the porous vesicular carbon can provide abundant transmission channels for ions, so that the diphenyl disulfide / vesicular carbon used as an electrode material is beneficial to improving the transmission rate of the energy storage active ions and exhibits good ionic conductivity, thereby obtaining excellent rate performance. In summary, the porous vesicular carbon can effectively improve the stability and ionic conductivity of the composite material. Compared with the porous graphene, porous carbon spheres and other porous carbons as carriers to load diphenyl disulfide, the diphenyl disulfide is mainly stabilized by the physical adsorption of carbon on the diphenyl disulfide, and there is no space confinement effect of the vesicular structure, so the dissolution and loss of the diphenyl disulfide cannot be well improved.

[0042] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0043] The experimental materials used in the embodiments of the present application are all conventional experimental materials in the art and can be purchased through commercial channels.

[0044] Example 1: Preparation of a diphenyl disulfide / vesicular carbon composite material

[0045] (1) 1g of methyl cellulose was added to 3mL of deionized water, and stirred until it became viscous to obtain a methyl cellulose dispersion; 5g of sodium bicarbonate and 0.5g of potassium hydroxide were mixed and then slowly added to the methyl cellulose dispersion, and stirred uniformly for 5min, and then freeze-dried at-40℃ for 48h to obtain a precursor;

[0046] The precursor was placed in a tube furnace, and first ventilated at room temperature for 30min under a high-purity argon protective atmosphere, and then heated to 200℃ at a heating rate of 4℃ / min, and then sintered at 200℃ for 2h, and then heated to 800℃ at a heating rate of 4℃ / min, and then sintered at 800℃ for 4h; after the reaction was completed, the temperature was lowered, the obtained product was washed with deionized water to remove the sodium bicarbonate template, and then freeze-dried at-40℃ for 48h to obtain vesicular carbon;

[0047] (2) 50 mg of diphenyl disulfide and 50 mg of vesicular carbon were ground and mixed uniformly to obtain a mixture; the mixture was placed in a glass tube, the glass tube was vacuumed to 0 Pa and then sealed; the glass tube containing the mixture was placed in a tube furnace, high-purity argon was introduced, the temperature was slowly increased to 63 °C at a temperature increasing rate of 2 °C / min, and the temperature was kept constant for 10 h; after the temperature of the tube furnace was naturally cooled to room temperature, the glass tube was taken out, and a solid sample was taken out from the glass tube, thereby obtaining a diphenyl disulfide / vesicular carbon composite material.

[0048] Example 2: Preparation method of a diphenyl disulfide / vesicular carbon composite material

[0049] (1) 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; 0.6 g of sodium bicarbonate and 0.1 g of potassium hydroxide were mixed and then slowly added to the methyl cellulose dispersion, and ground and stirred uniformly for 3 min, and then placed in a freezer for freeze-drying at -45 °C for 48 h to obtain a precursor;

[0050] The precursor was placed in a tube furnace, and high-purity argon was introduced as a protective atmosphere; the temperature was increased to 250 °C at a temperature increasing rate of 3 °C / min, and then kept constant for 1 h; then the temperature was increased to 700 °C at a temperature increasing rate of 3 °C / min, and then kept constant for 5 h; after the reaction was completed, the temperature was decreased, the obtained product was washed with deionized water to remove the sodium bicarbonate template, and then placed in a freezer for freeze-drying at -45 °C for 48 h to obtain vesicular carbon;

[0051] (2) 150 mg of diphenyl disulfide and 50 mg of vesicular carbon were ground and mixed uniformly to obtain a mixture; the mixture was placed in a glass tube, the glass tube was vacuumed to 0 Pa and then sealed; the glass tube containing the mixture was placed in a tube furnace, high-purity argon was introduced, the temperature was slowly increased to 168 °C at a temperature increasing rate of 4 °C / min, and the temperature was kept constant for 6 h; after the temperature of the tube furnace was naturally cooled to room temperature, the glass tube was taken out, and a solid sample was taken out from the glass tube, thereby obtaining a diphenyl disulfide / vesicular carbon composite material.

[0052] Example 3: Preparation method of a diphenyl disulfide / vesicular carbon composite material

[0053] (1) 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; 2.6 g of sodium bicarbonate and 0.9 g of potassium hydroxide were mixed and then slowly added to the methyl cellulose dispersion, and ground and stirred uniformly for 8 min, and then placed in a freezer for freeze-drying at -35 °C for 48 h to obtain a precursor;

[0054] The precursor is placed in a tube furnace in a protective atmosphere of high-purity argon, first ventilated at room temperature for 30 min, then heated to 300°C at a heating rate of 5°C / min, and sintered at constant temperature for 3 h, and then heated to 900°C at a heating rate of 5°C / min, and sintered at constant temperature for 6 h; after the reaction is completed, the temperature is lowered, the obtained product is washed with deionized water to remove the sodium bicarbonate template, and then placed in a freeze dryer at -35°C for 48 h to obtain vesicular carbon;

[0055] (2) 250 mg of diphenyl disulfide and 50 mg of vesicular carbon are ground and uniformly mixed to obtain a mixture; the mixture is placed in a glass tube, the glass tube is vacuumed to 0 Pa and then sealed; the glass tube containing the mixture is placed in a tube furnace, high-purity argon is introduced, the temperature is slowly increased to 310°C at a heating rate of 5°C / min, and the temperature is kept constant for 10 h; after the temperature of the tube furnace is naturally cooled to room temperature, the glass tube is taken out, and the solid sample in the glass tube is taken out to obtain a diphenyl disulfide / vesicular carbon composite material.

[0056] Comparative Example 1: Preparation method of a diphenyl disulfide / vesicular carbon composite material

[0057] 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 as follows:

[0058] 1 g of methyl cellulose is added to 3 mL of deionized water, and stirred until it becomes viscous to obtain a methyl cellulose dispersion; 5 g of sodium bicarbonate and 0.08 g of potassium hydroxide are mixed and then slowly added to the methyl cellulose dispersion, and stirred until uniform; the mixture is freeze-dried to obtain a precursor; the precursor is placed in a tube furnace in a protective atmosphere of high-purity argon, first ventilated at room temperature for 30 min, then sintered at constant temperature for 2 h at 200°C, and then sintered at constant temperature for 4 h at 800°C; after the reaction is completed, the temperature is lowered, the obtained product is washed with deionized water to remove the sodium bicarbonate template, and then placed in a freeze dryer for 48 h to obtain vesicular carbon; then the vesicular carbon and diphenyl disulfide are mixed by melt diffusion according to the method of Example 1 to obtain a diphenyl disulfide / vesicular carbon composite material.

[0059] Comparative Example 2: Preparation method of a diphenyl disulfide / porous carbon composite material

[0060] 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 as follows:

[0061] 1 g methyl cellulose was added into 3 mL deionized water and stirred until it became viscous to obtain a methyl cellulose dispersion; 5 g sodium bicarbonate and 1 g potassium hydroxide were mixed and then slowly added into the methyl cellulose dispersion and stirred until uniform; the mixture was freeze-dried to obtain a precursor; the precursor was placed in a tube furnace and sintered at 200 ℃ for 2 h and then at 800 ℃ for 4 h under a high-purity argon atmosphere; after the reaction, the product was cooled and washed with deionized water to remove the sodium bicarbonate template, and then dried in a freeze dryer for 48 h to obtain porous carbon; then the porous carbon and diphenyl disulfide were mixed and subjected to melt diffusion according to the method of Example 1 to obtain a diphenyl disulfide / porous carbon composite material.

[0062] Test Example 1: Structural characterization

[0063] 1. The diphenyl disulfide / vesicular carbon composite material prepared in Example 1 was subjected to electron microscope analysis and EDS Mapping analysis. The results are shown in FIGS. Figure 1 and Figure 2

[0064] As can be seen from FIGS. Figure 1 , the diphenyl disulfide / vesicular carbon composite material prepared in Example 1 not only retains the three-dimensional vesicular structure of vesicular carbon, but also ensures that the diphenyl disulfide is loaded on the surface and vesicular structure of the vesicular carbon. As can be seen from FIG. Figure 2 , the S element in the structure of the diphenyl disulfide is uniformly loaded on the vesicular carbon, proving the successful preparation of the diphenyl disulfide / vesicular carbon composite material.

[0065] 2. The composite material prepared in Comparative Example 1-2 was subjected to electron microscope analysis, and the results are shown in FIG. Figures 3-4

[0066] As can be seen from FIG. Figure 3 , when the amount of KOH is too small, the diphenyl disulfide / vesicular carbon composite material prepared retains the three-dimensional vesicular structure of vesicular carbon, but the diphenyl disulfide is mostly loaded on the surface of the vesicular carbon and little is loaded inside the vesicular carbon. As can be seen from FIG. Figure 4 , when the amount of KOH is too large, the porous carbon in the diphenyl disulfide / porous carbon composite material prepared presents an open pore structure and does not well retain the open and interconnected pore structure inside the vesicular carbon.

[0067] Test Example 2: Electrochemical properties

[0068] Diphenyl disulfide, vesicular carbon prepared in step (1) of Example 1, diphenyl disulfide / vesicular carbon composite material prepared in Example 1, and composite material prepared in Comparative Example 1-2 were respectively 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:​​

[0069] (1) Respectively take 16 mg of active material, mix it with 2 mg of acetylene black and 2 mg of polyvinylidene fluoride, and grind for 30 min to obtain a mixture, add the mixture to 800 μL of N-methylpyrrolidone, and ultrasonically disperse for 2 h to obtain a dispersion liquid; carbon paper prepared from carbon nanotubes is used as a current collector, and 50 uL of the dispersion liquid is respectively dropped and coated on the carbon paper, which is placed in a vacuum dryer at 60°C for 12 h to prepare an electrode sheet;

[0070] (2) A battery is assembled using a battery mold of the type of Shewei Locke, the electrode sheet prepared in step (1) is used as a positive electrode sheet, a high-purity aluminum foil is used as a negative electrode sheet, a glass fiber membrane is used as a separator, and AlCl3 / 1-ethyl-3-methylimidazolium chloride ionic liquid is used as an electrolyte to assemble an aluminum ion battery;

[0071] (3) The assembled aluminum ion battery is placed on a Shanghai Chenhua CHI660D electrochemical workstation and a LANHE CT2001A type battery charge-discharge instrument for electrochemical performance testing, wherein the CV test parameter settings are: a voltage range of 0.1-2.3 V; the constant current charge-discharge test parameter settings are: a voltage range of 0.1-2.3 V and a current density of 100-500 mA / g. The results are shown in Figure 5 and Figure 6 .

[0072] From Figure 5 it can be seen that a reversible redox reaction occurs during the charge-discharge process of the battery, and stable oxidation-reduction peaks appear at 1.32 V-1.17 V. From Figure 6 it can be seen that under the same test conditions, the discharge specific capacity of the vesicular carbon and diphenyl disulfide is 44 mAh / g and 147 mAh / g, respectively, and the discharge specific capacity of the diphenyl disulfide / vesicular carbon composite material is 247 mAh / g. The reason is that the addition of vesicular carbon not only alleviates the dissolution loss of diphenyl disulfide in the electrolyte, but also to some extent, improves the effective utilization rate of the diphenyl disulfide electrode active material, thereby further improving the specific capacity of the composite material. Therefore, diphenyl disulfide and vesicular carbon have a synergistic effect on improving the discharge specific capacity of the composite material.

[0073] Figure 7 The results of the cycle stability test of the electrodes of different materials are shown in Figure 7It can be seen that after the same number of cycles, the discharge specific capacity of the diphenyl disulfide electrode is 91 mAh / g after 60 cycles, and the capacity retention rate is only 13% of the initial capacity; while the discharge specific capacity of the diphenyl disulfide / vesicular carbon composite electrode can still be maintained at about 240 mAh / g after 60 cycles, which is 82% of the initial discharge specific capacity, and the stability of the electrode is greatly improved compared with the diphenyl disulfide electrode. At the same time, after 60 cycles, the discharge specific capacity of the diphenyl disulfide / vesicular carbon composite electrode prepared in Comparative Example 1 and the diphenyl disulfide / porous carbon composite electrode prepared in Comparative Example 2 is 138 mAh / g and 133 mAh / g, respectively, and the capacity retention rate is 38% and 43%, respectively, relative to the initial discharge specific capacity, and the improvement in the cycle performance of the electrode prepared in Example 1 is limited compared with the diphenyl disulfide / vesicular carbon composite electrode.

[0074] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. Use of diphenyl disulfide / vesicular carbon composite as a positive electrode material for aluminum-ion batteries, characterized in that, The diphenyl disulfide / vesicular carbon composite material is prepared by the following method: (1) mixing sodium bicarbonate and potassium hydroxide, then adding into methyl cellulose dispersion solution, grinding and mixing uniformly, drying to obtain a precursor; placing the precursor in an inert atmosphere and heating to react, after the reaction is completed, purifying after cooling to obtain vesicular carbon; The mass ratio of methyl cellulose, potassium hydroxide and sodium bicarbonate in the methyl cellulose dispersion solution is 1: (0.1-0.9): (0.6-5); (2) mixing diphenyl disulfide and vesicular carbon according to a mass ratio of (1-5):1 to obtain a mixture, placing the mixture in a vacuum and inert atmosphere and heating to react, collecting the solid after reaction, which is the diphenyl disulfide / vesicular carbon composite material.

2. Use according to claim 1, wherein In step (1), the methyl cellulose dispersion solution is prepared by mixing methyl cellulose and deionized water according to a liquid ratio of (1.5-2.5) g:6 mL.

3. The use according to claim 1, wherein In step (1), the grinding time is 3-8 min; the drying method is freeze-drying, the freeze-drying temperature is -45~-35℃, and the freeze-drying time is 48 h.

4. The use according to claim 1, wherein In step (1), the inert atmosphere is argon atmosphere, and the specific operation of heating is as follows: first, heating at a temperature increasing rate of 3-5℃ / min to 200-300℃, and holding for 1-3 h; then, heating at a temperature increasing rate of 3-5℃ / min to 700-900℃, and holding for 4-6 h.

5. The use according to claim 1, wherein In step (2), the inert atmosphere is argon atmosphere.

6. The use according to claim 1, wherein In step (2), the specific operation of heating is as follows: heating at a temperature increasing rate of 2-5℃ / min to 63-310℃, and holding for 6-10 h.

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