Antimony-based composite material, preparation method thereof and secondary battery

Abstract

The invention provides an antimony-based composite material, a preparation method thereof and a secondary battery. The preparation method comprises the following steps: preparation of GO-Sb2S3 nanosheets: preparing graphene oxide, an antimony source, HCl, a surfactant P123 and a surfactant PVP into a first dispersion liquid; carrying out first standing on the first dispersion liquid to obtain a second dispersion liquid; adding a sulfur source into the second dispersion liquid, and carrying out first reaction and second standing to obtain third dispersion liquid; performing first solid-liquid separation on the third dispersion liquid to obtain a first solid product; after the first solid product is subjected to first drying, GO-Sb2S3 nanosheets are obtained; and compounding a carbon source. According to the preparation method, a reaction route is accurately designed, sulfide of antimony grows on the surface of graphene oxide, and then the two-dimensional porous antimony-based composite material with a sandwich structure is prepared through a carbon source coating method.

Description

Technical Field

[0001] The present invention relates to the field of secondary batteries, and in particular to an antimony-based composite material, a preparation method thereof and a secondary battery. Background Art

[0002] As the most common energy storage system in modern electronic devices, the performance improvement of secondary batteries has always been a research hotspot in the fields of materials science and energy. As an important component of the battery, the negative electrode material directly affects the battery's energy density, cycle stability, and charge and discharge rate. Although traditional graphite negative electrode materials have been widely used, their theoretical capacity is close to the limit and it is difficult to meet the needs of future high-energy density batteries. Therefore, the development of new negative electrode materials has become a research focus.

[0003] Antimony (Sb), as an element with high theoretical specific capacity, has been widely studied as anode material for secondary batteries in recent years. Antimony has high electrochemical activity and can react with lithium / sodium / potassium ions to form alloys, thus providing a high specific capacity. In addition, the theoretical specific capacity of antimony is as high as 660mAh / g, which is much higher than the 372mAh / g of graphite, which makes antimony-based materials have great potential in improving battery energy density.

[0004] However, antimony-based negative electrode materials also face some challenges in practical applications. First, antimony has a large volume expansion during the charge and discharge process, which can lead to the destruction of the material structure and the peeling of the electrode, thus affecting the cycle stability of the battery. Second, antimony has a relatively low conductivity, which limits its charge and discharge rate and rate performance. In addition, antimony is easily oxidized in the air, which also requires special protective measures during the battery manufacturing process.

[0005] To overcome these challenges, researchers have adopted a variety of strategies to optimize the performance of antimony-based negative electrode materials. These strategies include: First, through methods such as nano-sizing, porosification or construction of composite materials, the impact of volume expansion can be reduced and the structural stability of the material can be improved. Second, by introducing a protective layer or a conductive layer on the surface of antimony, the conductivity and antioxidant capacity of the material can be improved. Third, the electrochemical properties of antimony-based negative electrodes can be improved by adjusting the electrolyte formulation, optimizing the charging strategy, and other methods. In addition, by compounding antimony with other materials (such as carbon materials, metal oxides, etc.), the synergistic effect of different materials can be utilized to improve the overall performance.

[0006] However, despite the use of the above method, the obtained antimony-based composite material still has the defects of poor cycle stability and low conductivity, and it is difficult to meet the actual application requirements of the secondary battery in which it is used.

[0007] Based on this, how to optimize the structure of antimony-based composite materials from the perspective of preparation technology so that they can exhibit higher electrochemical performance and longer cycle life is one of the technical problems that need to be solved in this field. Summary of the invention

[0008] The main purpose of the present invention is to provide an antimony-based composite material, a preparation method thereof and a secondary battery, so as to solve the problems of poor electrochemical performance and long cycle stability of antimony-based materials in the prior art.

[0009] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a method for preparing an antimony-based composite material, comprising: step S1, preparation of GO-Sb2S3 nanosheets: step S1-1, preparing graphene oxide, antimony source, HCl, surfactant P123 and surfactant PVP into a first dispersion; step S1-2, obtaining a second dispersion after the first dispersion is allowed to stand for a first time; step S1-3, adding a sulfur source to the second dispersion, obtaining a third dispersion after a first reaction and a second standing; step S1-4, treating the third dispersion The dispersion is subjected to a first solid-liquid separation to obtain a first solid product; after the first solid product is subjected to a first drying, GO-Sb2S3 nanosheets are obtained; step S2, compounding of the carbon source: step S2-1, preparing a buffer solution with a pH value of 5.8 to 9.0; step S2-2, adding the carbon source and GO-Sb2S3 nanosheets to the buffer solution, and after a second reaction, a fourth dispersion is obtained; step S2-3, the fourth dispersion is subjected to a second solid-liquid separation to obtain a second solid product; after a second drying and calcination of the second solid product, an antimony-based composite material is obtained.

[0010] Further, in step S1, in the first dispersion, the weight ratio of the graphene oxide, the antimony source and the HCl is 1: (5-20): (30-50), preferably 1: (17-18): (30-35); and / or, in the first dispersion, the mass concentration of the surfactant is 10wt% to 30wt%, preferably 20wt% to 25wt%; and / or, in the step S1-3, the amount of the sulfur source and the antimony source in the second dispersion The ratio of the substance is (0.5-1.5): 1, preferably (1.2-1.5): 1; and / or, the weight ratio of the surfactant P123 and the surfactant PVP is (3-4): 1.

[0011] Further, in step S1-2, the first standing time is 2h to 3h, and the first standing is carried out at 45°C to 50°C; in step S1-3, the first reaction is achieved by stirring, and the stirring time is 1min to 1.5min; and / or, the second standing time is 10h to 12h, and the second standing is carried out at 75°C to 80°C.

[0012] Furthermore, in step S1-4, the first drying is vacuum freeze drying, and the vacuum freeze drying time is 12h to 14h.

[0013] Furthermore, in step S2, the weight ratio of the carbon source to the GO-Sb2S3 nanosheets is (0.8-1.2):1.

[0014] Furthermore, in step S2-2, the second reaction is achieved by stirring, and the stirring time is 5 h to 6 h.

[0015] Furthermore, in step S2-3, the second drying is vacuum freeze drying, and the vacuum freeze drying time is 12h to 14h; and / or the heating rate of calcination is 2.0℃ / min to 2.5℃ / min, the insulation temperature is 400℃ to 420℃, and the insulation time is 2.5h to 3h; preferably, calcination is carried out in a protective atmosphere, and more preferably the protective atmosphere is argon.

[0016] Further, the antimony source is selected from one or more of antimony trichloride, antimony acetate and potassium antimony tartrate; and / or, the sulfur source is selected from one or more of thioacetamide, thiourea, lithium sulfide, hydrosulfuric acid, potassium sulfide, sodium sulfide and ammonium sulfide; and / or, the carbon source is selected from one or more of glucose, plant cellulose, sucrose, phenolic resin, maltose, starch, resorcinol-formaldehyde resin and tannic acid, preferably tannic acid; and / or, HCl is added in the form of a hydrochloric acid solution, and the mass concentration of the hydrochloric acid solution is 35% to 37%.

[0017] The second aspect of the present invention provides an antimony-based composite material, which is prepared by the above-mentioned method for preparing the antimony-based composite material.

[0018] A third aspect of the present invention provides a secondary battery comprising a working electrode, a counter electrode and an electrolyte, wherein the secondary battery is selected from a lithium ion battery, a sodium ion battery and a potassium ion battery, and the working electrode comprises the above-mentioned antimony-based composite material.

[0019] By applying the technical solution of the present invention, antimony sulfide is grown on the surface of graphene oxide through precise design of the reaction route, and then a two-dimensional porous antimony-based composite material with a sandwich structure is prepared through a carbon source coating method. The obtained antimony-based composite material exhibits excellent specific surface area and pore size distribution, and has a stable structure, and thus has good electrochemical properties and long cycle stability. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0021] As described in the background technology, the antimony-based composite materials in the prior art have the problems of poor electrochemical performance and long cycle stability. In order to solve the above technical problems, the first aspect of the present invention provides a method for preparing an antimony-based composite material, including: step S1, preparation of GO-Sb2S3 nanosheets: step S1-1, preparing graphene oxide, antimony source, HCl, surfactant P123 and surfactant PVP into a first dispersion; step S1-2, the first dispersion is subjected to a first standing to obtain a second dispersion; step S1-3, adding a sulfur source to the second dispersion, and after a first reaction and a second standing, obtaining a third dispersion; step S1-4, treating the third dispersion The dispersion is subjected to a first solid-liquid separation to obtain a first solid product; the first solid product is subjected to a first drying to obtain GO-Sb2S3 nanosheets; step S2, compounding of the carbon source: step S2-1, preparing a buffer solution with a pH value of 5.8 to 9.0; step S2-2, adding the carbon source and GO-Sb2S3 nanosheets to the buffer solution, and obtaining a fourth dispersion after a second reaction; step S2-3, performing a second solid-liquid separation on the fourth dispersion to obtain a second solid product; after a second drying and calcination of the second solid product, an antimony-based composite material is obtained.

[0022] The preparation method provided by the present invention realizes the growth of antimony sulfide on the surface of graphene oxide (GO) by designing the preparation process of the antimony-based composite material in stages and steps, and then coating it with a carbon source to finally prepare a two-dimensional porous antimony-based composite material with a sandwich structure. Specifically:

[0023] First, based on the thermal phase transition mechanism of two-dimensional P123 and PVP surfactant lamellar micelles, two-dimensional Sb2S3 nanosheets were grown on the GO surface by in-situ growth. In the preparation process of the above GO-Sb2S3 nanosheets, before the addition of the sulfur source, the first dispersion liquid including graphene oxide, antimony source, HCl, surfactant P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock compound, PEO-PPO-PEO) and surfactant PVP was subjected to the first static treatment to facilitate more sufficient contact between the reactants and form a more uniform second dispersion liquid, laying the foundation for the subsequent addition of the sulfur source and the formation of the nanosheets. Afterwards, the addition of the sulfur source promoted the formation of Sb2S3, and the setting of the second static process ensured the uniform growth of Sb2S3 nanosheets on the graphene oxide surface.

[0024] Subsequently, the carbon source is in situ polymerized on the GO-Sb2S3 surface to prepare a two-dimensional GO-Sb2S3 / carbon source sandwich structure; finally, through high-temperature heat treatment, i.e. calcination, GO is reduced to rGO to increase conductivity, and the carbon source is reduced to carbon to inhibit the volume expansion of antimony-based sulfides that may occur in practical applications, as well as to improve its conductivity to promote its stability.

[0025] In particular, relying on the above-mentioned special raw materials and surfactant type selection, the above-mentioned steps in the preparation method provided by the present invention cooperate with each other as an overall technical solution, that is, forming a complete technical route of configuration to obtain a first dispersion → first standing → first reaction → second standing → solid-liquid separation to obtain a first product → first drying → carbon coating → solid-liquid separation to obtain a second product → second drying, first calcination → obtaining a product, for the synthesis and preparation of sandwich-type porous antimony-based composite materials, compared with the commonly used methods in the field, the prepared material has a better pore structure, and the structural stability, thermal stability and chemical stability are also higher. That is to say, the above-mentioned steps in the preparation method provided by the present invention, in addition to the advantages and functions they have themselves, are more importantly able to cooperate with each other, that is, as an overall solution, to achieve the preparation of high-performance antimony-based composite materials.

[0026] In summary, the antimony-based composite material prepared by the above-mentioned preparation method designed by the present invention has more superior electrochemical properties, including higher storage performance, higher conductivity, and more obviously suppressed volume expansion and capacity attenuation problems.

[0027] In the above-mentioned method for preparing GO-Sb2S3 nanosheets, the main function of concentrated hydrochloric acid is to inhibit the hydrolysis of Sb ions, form a uniform solution, and provide an acidic environment that is conducive to the growth of Sb2S3 nanosheets. In some typical embodiments, the weight ratio of graphene oxide, antimony source and HCl in the first dispersion of step S1 is 1: (5-20): (30-50). More preferably, this weight ratio relationship is 1: (17-18): (30-35), and under this weight ratio relationship, the subsequent growth process of Sb2S3 nanosheets on the GO surface can be more effectively optimized, and a more ideal morphology and a more suitable active material loading can be obtained. At the same time, the uniformity and chemical stability of the obtained GO-Sb2S3 nanosheets can be more effectively improved, so that they show higher electrochemical stability after subsequent carbon coating.

[0028] More importantly, the surfactant P123 and PVP in the first dispersion are used to form a microphase separation structure, providing a template or guide for the growth of Sb2S3 nanosheets, helping to control their morphology and size, and avoiding the agglomeration of Sb2S3 nanosheets. Especially in the synthesis system provided by the present invention, P123 and PVP can synergistically induce the formation of lamellar micelles, allowing Sb2S3 nanosheets to grow along a specific direction, thereby obtaining a two-dimensional structure. At the same time, P123 and PVP can also be used as surfactants to reduce the surface tension in the dispersion, improve dispersibility, and make Sb2S3 nanosheets more evenly distributed and grown on the surface of GO, thereby enhancing the uniformity and stability of the resulting GO-Sb2S3 nanosheets and subsequent composite materials.

[0029] Especially, when the P123 in the solution system reaches a certain concentration, P123 begins to gel under the joint action of the hydrophilic section and the hydrophobic section. At this time, if its concentration continues to increase, the number of P123 micelles increases, and the viscosity of the solution increases, so for the maintenance of the free energy of the solution system, micelles and micelles reunite, and ultimately affect the assembly of inorganic salt ions on the micelle surface. And in order to suppress the reunion between micelles and make it better dispersed in the solution system, the present invention adds the surfactant polyvinyl pyrrolidone (PVP) as an auxiliary template agent to the solution system containing P123. PVP can adhere to the surface of P123 micelles due to its molecular structure characteristics, forming mixed micelles, thereby improving the assembly efficiency of inorganic salt ions on micelles. PVP also has good hydrophilicity and has a good spatial shielding effect in the solution. Specifically, the PVP molecule enters the inside of the P123 micelle in a way that the hydrophilic head faces outward and the hydrophobic group faces inward, forming an active mixed micelle. This mixed micelle has stronger hydrophilicity and is not easy to agglomerate, making the assembly efficiency of inorganic salt ions on the micelle higher.

[0030] That is to say, compared with the case where P123 or PVP is used alone, the synergistic use of the two in a weight ratio of (3-4):1 (P123:PVP) can form a more stable dispersion system, reduce agglomeration, make Sb2S3 grow more uniformly on the GO surface, and ultimately improve the structural integrity of the resulting GO-Sb2S3 nanosheets, and enable them to exhibit superior electrochemical performance after subsequent composite with a carbon source.

[0031] Based on the above reasons, the inventors have conducted a large number of experiments and have made the total mass concentration of the two to be 10wt% to 30wt%, more preferably 20wt% to 25wt%, and further preferably 21% to 22wt%, so as to better control the surface morphology of the obtained GO-Sb2S3 nanosheets and reduce the possibility of uneven morphology or incomplete growth due to excess or insufficient amount. At the same time, the combination mode between the Sb2S3 nanosheets obtained by the reaction and the graphene oxide, as well as the conductivity and porosity characteristics of the final material are optimized to make it show higher electrochemical performance.

[0032] In the process of forming Sb2S3 nanosheets, the inventors further conducted a large number of experiments and set the molar ratio of the sulfur source in step S1-3 to the antimony source in the second dispersion to (0.5-1.5): 1, and more preferably to (1.2-1.5): 1. Under this preferred and more preferred molar ratio relationship, the growth of Sb2S3 nanosheets can be more accurately controlled, and the size, thickness and distribution of the obtained Sb2S3 nanosheets can be further optimized, thereby improving the conductivity and stability of the composite material in which the nanosheets are located.

[0033] Further, in order to facilitate more sufficient contact and reaction between the reactants, form a more uniform second dispersion, and provide good conditions for the subsequent formation of nanosheets, exemplarily, in step S1-2, the first standing time is 2h to 3h, and the first standing is carried out at 45°C to 50°C. In order to promote the formation of GO-Sb2S3 nanosheets and reduce the destruction of the nanostructure that may be caused by too long stirring time, thereby obtaining a composite material with better electrochemical properties, exemplarily, in step S1-3, the first reaction is achieved by stirring, and the stirring time is 1min to 1.5min. And, after stirring, in order to promote more uniform growth of Sb2S3 nanosheets on the surface of graphene oxide, form more stable, less impurity, and porous GO-Sb2S3 nanosheets, so that the resulting composite material exhibits higher electrochemical properties, exemplarily, the second standing time is 10h to 12h, and the second standing is carried out at 75°C to 80°C.

[0034] In some typical embodiments, in order to more effectively remove moisture from the first solid product while maintaining the porous structure of the material and avoiding agglomeration of the obtained material and making it difficult to disperse in an aqueous solution, illustratively, in step S1-4, the first drying is vacuum freeze drying, and the vacuum freeze drying time is 12 h to 14 h.

[0035] Furthermore, the obtained GO-Sb2S3 nanosheets are a porous structure including mesopores and macropores, and the average pore size of the mesopores is The average pore size of the macropores is That is to say, because the GO-Sb2S3 nanosheets obtained by the above preparation method have more suitable pore structure characteristics and pore size distribution, an antimony-based composite material with better electrochemical performance can be obtained after being coated with a carbon source.

[0036] In order to obtain a better coating effect, the inventors conducted a large number of experiments and set the weight ratio of carbon source to GO-Sb2S3 nanosheets to (0.8-1.2):1. Carbon coating significantly improves the electrochemical performance of the material by improving the conductivity of the material and providing a stable chemical and electrochemical reaction interface; if the carbon coating is too thick, the energy density decreases, the internal resistance increases, the temperature rise is too high, and the manufacturing cost increases; if the carbon coating is too thin, the conductivity decreases, the chemical stability is insufficient, and the mechanical strength decreases. It is preferred that it is within this range, which can promote the content of the carbon coating layer in the final composite material to be moderate, while reducing the decrease in material energy density, increase in internal resistance, excessive temperature rise, and increased manufacturing cost caused by excessive carbon content, thereby making the resulting composite material exhibit higher conductivity, electrochemical performance and stability.

[0037] In several typical embodiments, the second reaction in step S2-2 is achieved by stirring, and the stirring time is 5h to 6h. Such conditions are conducive to the uniform compounding of the carbon source and the GO-Sb2S3 nanosheets, so that the initial coating of the carbon source can be carried out more effectively, forming a more structurally stable GO-Sb2S3 / carbon source precursor to be calcined, and finally forming an antimony-based composite material with better and more stable electrochemical properties after calcination.

[0038] Furthermore, in order to more effectively avoid the possible influence of moisture before calcination, so that the final composite material structure is more stable, with fewer impurities and better electrochemical performance, the second drying in step S2-3 is vacuum freeze drying, and the vacuum freeze drying time is 12h to 14h. Exemplarily, the heating rate of calcination is 2.0℃ / min to 2.5℃ / min, the holding temperature is 400℃ to 420℃, and the holding time is 2.5h to 3h.

[0039] The above calcination conditions can promote more complete polymerization and carbonization of the carbon source, forming a more stable carbon coating layer, thereby more effectively inhibiting the volume expansion of the antimony-based sulfide during the charge and discharge process, and improving its conductivity, and ultimately improving the cycle stability of the negative electrode material in which it is located. At the same time, the calcination conditions can also help to further reduce GO to rGO, thereby enhancing the conductivity of the resulting composite material. In addition, the above calcination conditions can also more effectively reduce the internal stress generated by the material due to temperature changes during the heating process, further enhance its structural integrity, and keep the resulting composite material structure stable in the subsequent charge and discharge cycles of the application, inhibiting structural damage and performance degradation.

[0040] In order to reduce the introduction of impurities during the final calcination process and to more effectively improve the electrochemical properties of the antimony-based composite material obtained by calcination, the first calcination is exemplarily performed in a protective atmosphere, which may be argon.

[0041] In several typical embodiments, the antimony source is selected from one or more of antimony trichloride, antimony acetate and potassium antimony tartrate; and / or, the sulfur source is selected from one or more of thioacetamide, thiourea, lithium sulfide, hydrosulfuric acid, potassium sulfide, sodium sulfide and ammonium sulfide; and / or, the carbon source is selected from one or more of glucose, plant cellulose, sucrose, phenolic resin, maltose, starch, resorcinol-formaldehyde resin and tannic acid; and / or, HCl is added in the form of a hydrochloric acid solution, and the mass concentration of the hydrochloric acid solution is 35% to 37%. In several more typical embodiments, the antimony source is exemplarily antimony trichloride and the sulfur source is thioacetamide. At this time, thioacetamide will decompose in the reaction system to produce hydrogen sulfide (H2S), which reacts with antimony trichloride to generate Sb2S3 nanosheets. Because the compatibility between the two reactants is better, Sb2S3 nanosheets with higher purity and more stable structure can be generated on the surface of graphene oxide, and finally an antimony-based composite material with superior electrochemical properties is obtained.

[0042] And, further, exemplarily, the carbon source is tannic acid, which can interact with the surface of the GO-Sb2S3 nanosheets to be coated through the abundant phenolic hydroxyl groups in the structure to form a tight and stable coating layer. This layer can not only protect the internal GO-Sb2S3 nanosheets from the external environment, but also affect the solubility, stability and biocompatibility of the substance by adjusting the surface properties, and finally obtain an antimony-based composite material with a more stable structure and better recyclability. In particular, when the carbon source is tannic acid, the inventor has optimized the pH value of the buffer used in step (2) to 5.8-7.2 through a large number of experiments, so as to facilitate more effective coating and stratification of tannic acid, pre-form a coating layer with a more suitable thickness, and then improve the various properties of the composite material obtained after subsequent calcination.

[0043] The second aspect of the present invention provides an antimony-based composite material, which is prepared by the above-mentioned preparation method of the antimony-based composite material. The antimony-based composite material obtained by the above-mentioned preparation method provided by the present invention has a special porous structure, which is conducive to improving the electrochemical performance of the secondary battery.

[0044] It should be noted that due to the particularity of the materials field and the limitations of existing testing and characterization methods, it is difficult to conduct a comprehensive quantitative characterization of the complex microstructure of the antimony-based composite material obtained above, but the performance test results show that the antimony-based composite material obtained in this application has better electrochemical properties and can significantly improve the various performances of the secondary battery in which it is used, especially the cycle stability.

[0045] The third aspect of the present invention provides a secondary battery, including a working electrode, a counter electrode and an electrolyte, wherein the secondary battery is selected from one of a lithium ion battery, a sodium ion battery and a potassium ion battery, and the working electrode includes the antimony-based composite material. Because the above-mentioned negative electrode material obtained by the present invention has both good electrochemical performance and structural stability, when it is used as a working electrode component in a secondary battery, the resulting battery also has comprehensively improved electrochemical performance, including improved first-cycle coulomb efficiency, excellent rate performance, long cycle life and good cycle stability, so that it can be well applied to multiple usage scenarios.

[0046] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0047] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0048] Example 1

[0049] A method for preparing an antimony-based composite material:

[0050] (1) Preparation of GO-Sb2S3 nanosheets:

[0051] (1-1) Preparation of graphene oxide (GO): Preparation was based on the improved Hummers method. 4 g of graphite powder, 24 g of KMnO4 and 196 mL of concentrated sulfuric acid were stirred at 5 ° C for 120 min, then heated to 35 ° C and stirred for 90 min, and then stirred at 45 ° C, 55 ° C, 75 ° C and 85 ° C for 30 min each. After the slurry becomes viscous, 500 mL of water is added. Then 30% H2O2 is added to the system until it turns yellow. After standing for 12 hours, it is centrifugally washed with dilute HCl, centrifugally washed with water, and dialyzed to obtain GO, which is then prepared into a 2 mg / mL graphene oxide solution. Take 10 mL of the obtained graphene oxide solution in a 25 mL sample bottle, and then take 0.35 g of antimony trichloride and 1.6 mL of concentrated hydrochloric acid (mass concentration is 35%) and add it and stir evenly. Then, 1.875 g of surfactant P123 and 0.625 g of surfactant PVP (i.e., P123:PVP=3:1, weight ratio) were added thereto, and stirred below 10°C until completely dissolved to obtain a first dispersion. In the obtained first dispersion, the weight ratio of graphene oxide, antimony source, and HCl in concentrated hydrochloric acid was 1:17.5:33.3; the total mass concentration of the two surfactants was 21.5 wt%;

[0052] (1-2) The obtained first dispersion liquid was first allowed to stand in a 50° C. water area for 2 hours to obtain a second dispersion liquid.

[0053] (1-3) Then, 0.173 g of thioacetamide was added to the second dispersion (at this time, the molar ratio of the added sulfur source, i.e., thioacetamide, to the antimony in the antimony source was 3:2), and the mixture was rapidly stirred for 1 minute to carry out a first reaction, and then a second standing time was carried out in water at 80° C. for 12 hours to obtain a third dispersion.

[0054] (1-4) The black precipitate in the third dispersion is separated as the first solid product, which is washed three times by centrifugation with water, quenched in liquid nitrogen, and freeze-dried in vacuum for 12 hours to obtain a two-dimensional GO-Sb2S3 nanosheet.

[0055] (2) Carbon source compound:

[0056] (2-1) A buffer with a pH of 7.0 was prepared by mixing 100 mM buffer (Bis-Tris buffer) and 600 mM NaCl.

[0057] (2-2) Add 200 mg of tannic acid and 200 mg of the GO-Sb2S3 nanosheets obtained above (at this time, the weight ratio of the carbon source to the GO-Sb2S3 nanosheets is 1:1) to 100 mL of buffer solution and slowly stir for 6 hours to carry out a second reaction to obtain a fourth dispersion.

[0058] (2-3) The black precipitate in the fourth dispersion is separated as the second solid product, washed three times by centrifugation with water, quenched with liquid nitrogen, and freeze-dried in a vacuum for 12 hours, and then calcined. The calcination is carried out in an argon atmosphere at a heating rate of 2°C / min, a holding temperature of 400°C, and a holding time of 3 hours to obtain an antimony-based composite material.

[0059] Example 2

[0060] A method for preparing an antimony-based composite material:

[0061] The difference between this embodiment and embodiment 1 is only the amount of each raw material used in step (1), specifically:

[0062] The amount of antimony trichloride added was changed to 0.1 g, the amount of 35% concentrated hydrochloric acid added was changed to 2.34 mL, and the amount of thioacetamide added was changed to 0.076 g.

[0063] At this time, in the obtained first dispersion, the weight ratio of graphene oxide, antimony source and HCl in concentrated hydrochloric acid is changed to 1:5:50; and the molar ratio of the added sulfur source and antimony source is changed to 2.3:1.

[0064] Example 3

[0065] A method for preparing an antimony-based composite material:

[0066] The difference between this embodiment and embodiment 1 is only the amount of each raw material used in step (1), specifically:

[0067] The amount of antimony trichloride added was changed to 0.24 g, the amount of 35% concentrated hydrochloric acid added was changed to 1.404 mL, and the amount of thioacetamide added was changed to 0.04 g.

[0068] At this time, in the obtained first dispersion, the weight ratio of graphene oxide, antimony source and HCl in concentrated hydrochloric acid is changed to 1:12:30; and the molar ratio of the added sulfur source and antimony source is changed to 1:2.

[0069] Example 4

[0070] A method for preparing an antimony-based composite material:

[0071] The only difference between this embodiment and embodiment 1 is that the amount of surfactant P123 added in step (1-1) is changed to 0.75 g, and the amount of surfactant PVP added is changed to 0.25 g.

[0072] At this time, the total mass concentration of the surfactant P123 and PVP in the first dispersion obtained was 8.6 wt %.

[0073] Example 5

[0074] A method for preparing an antimony-based composite material:

[0075] The only difference between this embodiment and embodiment 1 is that the amount of surfactant P123 added in step (1-1) is changed to 3.75 g, and the amount of surfactant PVP added is changed to 1.25 g.

[0076] At this time, the total mass concentration of the surfactant P123 and PVP in the first dispersion obtained was 43.1 wt %.

[0077] Example 6

[0078] A method for preparing an antimony-based composite material:

[0079] The difference between this embodiment and embodiment 1 is only in the experimental conditions in step (1-2) and step (1-3), specifically:

[0080] (1-2) The obtained first dispersion solution was first allowed to stand in a 60° C. water area for 1 hour to obtain a second dispersion solution.

[0081] (1-3) Then, 100 mg of thioacetamide was added to the second dispersion, and the mixture was rapidly stirred for 0.5 minutes to perform a first reaction. The mixture was then allowed to stand for 14 hours in a 90° C. water solution to obtain a third dispersion.

[0082] Example 7

[0083] A method for preparing an antimony-based composite material:

[0084] The difference between this embodiment and embodiment 1 is only in the experimental conditions in step (1-2) and step (1-3), specifically:

[0085] (1-2) The obtained first dispersion solution was first allowed to stand in a 30° C. water area for 4 hours to obtain a second dispersion solution.

[0086] (1-3) Then, 100 mg of thioacetamide was added to the second dispersion, and the mixture was rapidly stirred for 3 minutes to perform a first reaction. The mixture was then allowed to stand for 8 hours in a 60° C. water area to obtain a third dispersion.

[0087] Example 8

[0088] A method for preparing an antimony-based composite material:

[0089] The only difference between this embodiment and embodiment 1 is that the amount of tannic acid added in step (2-2) is changed to 100 mg.

[0090] At this time, the weight ratio of carbon source to GO-Sb2S3 nanosheets was 0.5:1.

[0091] Example 9

[0092] A method for preparing an antimony-based composite material:

[0093] The only difference between this embodiment and embodiment 1 is that the amount of tannic acid added in step (2-2) is changed to 300 mg.

[0094] At this time, the weight ratio of carbon source to GO-Sb2S3 nanosheets was 1.5:1.

[0095] Example 10

[0096] A method for preparing an antimony-based composite material:

[0097] The only difference between this embodiment and embodiment 1 is that the calcination conditions in step (2-3) are changed to: a heating rate of 1.5° C. / min, a holding temperature of 350° C., and a holding time of 5 hours.

[0098] Embodiment 11

[0099] A method for preparing an antimony-based composite material:

[0100] The only difference between this embodiment and embodiment 1 is that the calcination conditions in step (2-3) are changed to: a heating rate of 3.0° C. / min, a holding temperature of 500° C., and a holding time of 2.5 hours.

[0101] Comparative Example 1

[0102] A method for preparing antimony-based materials:

[0103] (1) In a 25 mL sample bottle, 0.35 g of antimony trichloride and 1.6 mL of concentrated hydrochloric acid (mass concentration of 35%) were added to 10 mL of water and stirred evenly. Then, 1.875 g of surfactant P123 and 0.625 g of surfactant PVP (i.e., P123:PVP=3:1, weight ratio) were added thereto and stirred at below 10°C until completely dissolved to obtain a first dispersion.

[0104] (1-2) The obtained first dispersion liquid was first allowed to stand in a 50° C. water area for 2 hours to obtain a second dispersion liquid.

[0105] (1-3) Then, 0.173 g of thioacetamide was added to the second dispersion (at this time, the molar ratio of the added sulfur source, i.e., thioacetamide, to the antimony in the antimony source was 3:2), and the mixture was rapidly stirred for 1 minute to carry out a first reaction, and then a second standing time was carried out in water at 80° C. for 12 hours to obtain a third dispersion.

[0106] (1-4) The grass green precipitate in the third dispersion is separated as the first solid product, which is washed three times by centrifugation with water, quenched in liquid nitrogen, and freeze-dried in vacuum for 12 hours to obtain Sb2S3 nanosheets.

[0107] That is, this comparative example only obtained two-dimensional Sb2S3 nanomaterials, which were directly used as the obtained negative electrode material.

[0108] Comparative Example 2

[0109] A method for preparing antimony-based materials:

[0110] The only difference between this comparative example and comparative example 1 is that P123 and PVP are not added, and Sb2S3 nanomaterial is finally obtained and directly used as the obtained negative electrode material.

[0111] Comparative Example 3

[0112] A method for preparing an antimony-based composite material:

[0113] The only difference between this comparative example and Example 1 is that the PVP in step (1) is replaced by an equal amount of P123.

[0114] Comparative Example 4

[0115] A method for preparing an antimony-based composite material:

[0116] The only difference between this comparative example and Example 1 is that the two-dimensional porous GO-Sb2S3 nanosheets obtained in step (1) are directly calcined under the calcination conditions in Example 1 to obtain two-dimensional porous rGO-Sb2S3 nanosheets, which are directly used as the obtained negative electrode material.

[0117] Comparative Example 5

[0118] A method for preparing an antimony-based composite material:

[0119] The only difference between this comparative example and Example 1 is that the calcination in step (2) is not performed, and the second solid product that has undergone the second drying is directly used as the obtained negative electrode material.

[0120] Battery sample preparation and performance test: The negative electrode materials obtained in each embodiment and comparative example were used as negative electrode active materials, and sodium metal was used as the counter electrode. Each negative electrode material, acetylene black and hydroxymethyl cellulose were added to water in a ratio of 8:1:1 and stirred for 12 hours, then coated on copper foil, transferred to a vacuum oven and heated at 75°C for 13 hours to obtain a negative electrode sheet, on which the negative electrode active material loading was 1.9 mg cm -2. CR2032 button cells were assembled using glass fiber membrane as separator and 1M NaClO4 as electrolyte. The constant current charge and discharge tests were performed on each battery sample using the Blue Electric test system to obtain the charge and discharge specific capacity at 0.2A / g, the capacity retention rate at the first efficiency and after 100 cycles, and the capacity retention rate after 1000 cycles at 2A / g.

[0121] The above test results are shown in Table 1.

[0122] Table 1

[0123]

[0124] From the above description, it can be seen that the above embodiments of the present invention realize the preparation of antimony-based composite materials with excellent electrochemical performance, and its microstructure is specifically that flaky antimony sulfide or antimony sulfide is loaded on graphene oxide, and the outer surface is coated with a carbon layer. The battery sample prepared by using the obtained antimony-based composite material as an active material exhibits high electrical performance, especially high charge and discharge specific capacity, first efficiency, and excellent long-cycle stability.

[0125] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an antimony-based composite material, characterized in that: include: Step S1, preparation of GO-Sb2S3 nanosheets: Step S1-1, preparing graphene oxide, antimony source, HCl, surfactant P123 and surfactant PVP into a first dispersion; Step S1-2, the first dispersion liquid is subjected to a first standing condition to obtain a second dispersion liquid; Step S1-3, adding a sulfur source to the second dispersion, and obtaining a third dispersion after a first reaction and a second standing. Step S1-4, performing a first solid-liquid separation on the third dispersion to obtain a first solid product; After the first solid product is dried for the first time, the GO-Sb2S3 nanosheets are obtained; Step S2, compounding of carbon source: Step S2-1, preparing a buffer solution with a pH of 5.8 to 9.0; Step S2-2, adding a carbon source and the GO-Sb2S3 nanosheets to the buffer solution, and obtaining a fourth dispersion after a second reaction; Step S2-3, performing a second solid-liquid separation on the fourth dispersion to obtain a second solid product; The antimony-based composite material is obtained after the second solid product is subjected to a second drying and calcination.

2. The method for preparing the antimony-based composite material according to claim 1, characterized in that: In the step S1, In the first dispersion, the weight ratio of the graphene oxide, the antimony source and the HCl is 1:(5-20):(30-50), preferably 1:(17-18):(30-35); and / or, in the first dispersion, the mass concentration of the surfactant is 10wt% to 30wt%, preferably 20wt% to 25wt%; And / or, in the step S1-3, the molar ratio of the sulfur source to the antimony source in the second dispersion is (0.5-1.5):1, preferably (1.2-1.5):1; And / or, the weight ratio of the surfactant P123 to the surfactant PVP is (3-4):

1.

3. The method for preparing the antimony-based composite material according to claim 1 or 2, characterized in that: In the step S1-2, the first standing time is 2 hours to 3 hours, and the first standing time is performed at 45° C. to 50° C.; In the step S1-3, the first reaction is achieved by stirring, and the stirring time is 1 min to 1.5 min; and / or, the second standing time is 10 h to 12 h, and the second standing is performed at 75° C. to 80° C.

4. The method for preparing the antimony-based composite material according to any one of claims 1 to 3, characterized in that: In the step S1-4, the first drying is vacuum freeze drying, and the time of the vacuum freeze drying is 12 hours to 14 hours.

5. The method for preparing the antimony-based composite material according to any one of claims 1 to 4, characterized in that: In the step S2, the weight ratio of the carbon source to the GO-Sb2S3 nanosheets is (0.8-1.2):

1.

6. The method for preparing the antimony-based composite material according to any one of claims 1 to 5, characterized in that: In the step S2-2, the second reaction is achieved by stirring, and the stirring time is 5 h to 6 h.

7. The method for preparing an antimony-based composite material according to any one of claims 1 to 6, characterized in that: In the step S2-3, The second drying is vacuum freeze drying, and the vacuum freeze drying time is 12h to 14h; and / or, The calcination temperature rise rate is 2.0°C / min to 2.5°C / min, the holding temperature is 400°C to 420°C, and the holding time is 2.5h to 3h; Preferably, the calcination is carried out in a protective atmosphere, more preferably the protective atmosphere is argon.

8. The method for preparing the antimony-based composite material according to any one of claims 1 to 7, characterized in that: The antimony source is selected from one or more of antimony trichloride, antimony acetate and potassium antimony tartrate; and / or, The sulfur source is selected from one or more of thioacetamide, thiourea, lithium sulfide, hydrosulfuric acid, potassium sulfide, sodium sulfide and ammonium sulfide; and / or, The carbon source is selected from one or more of glucose, plant cellulose, sucrose, phenolic resin, maltose, starch, resorcinol-formaldehyde resin and tannic acid, preferably tannic acid; and / or, The HCl is added in the form of a hydrochloric acid solution, and the mass concentration of the hydrochloric acid solution is 35% to 37%.

9. An antimony-based composite material, characterized in that: The antimony-based composite material is prepared by the method for preparing the antimony-based composite material according to any one of claims 1 to 8.

10. A secondary battery comprising a working electrode, a counter electrode and an electrolyte, characterized in that: The secondary battery is selected from one of a lithium ion battery, a sodium ion battery and a potassium ion battery, and the working electrode comprises the antimony-based composite material according to claim 9.

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