Antimony (tin)-based / carbon microsphere composite material and preparation method thereof

Abstract

The invention discloses an antimony (tin)-based / carbon microsphere composite material and a preparation method thereof, the antimony (tin)-based / carbon microsphere composite material is formed by taking compact carbon microspheres as a matrix and loading an antimony (tin)-based nano-particle active material, an antimony (tin) source and a carbon source are dispersed in water, atomized and sprayed into a high-temperature oil bath to form a composite microsphere precursor material, and the composite microsphere precursor material is carbonized at a high temperature in an inert atmosphere to obtain the antimony (tin)-based / carbon microsphere composite material. The antimony (tin)-based / carbon microsphere composite material with the density of 3.0-4.5 g / cm < 3 > can be prepared. The antimony (tin)-based / carbon microsphere composite material has high density, an antimony (tin)-based active material is limited in a carbon microsphere matrix, the problem of volume expansion in the charging and discharging process is effectively relieved, the antimony (tin)-based / carbon microsphere composite material is used as a sodium ion battery negative electrode material, the cycle stability of an electrode is improved, the service life of the electrode is prolonged, and the service life of the electrode is prolonged. The advantages of high specific capacity, good cycling stability and the like are shown.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy storage materials and electrochemistry, and relates to a negative electrode material for sodium-ion batteries, in particular to an antimony (tin)-based / carbon microsphere composite material and a preparation method thereof. Background Art

[0002] Lithium-ion batteries stand out among numerous energy storage systems with their excellent high energy density and long cycle life, becoming the leader in efficient energy storage. However, the dwindling lithium resources and high production costs limit the sustainable development of lithium-ion batteries. As a highly potential alternative to lithium-ion batteries in the field of large-scale energy storage, sodium-ion batteries have attracted much attention due to their abundant sodium resource reserves, similar reaction mechanisms to lithium-ion batteries, and close redox potentials.

[0003] As a popular research direction in current energy storage technologies, sodium-ion batteries face challenges in aspects such as energy density, cycle stability, and rate performance, which have become key problems that need to be overcome urgently on their development path. Among them, electrode materials are the key factors determining battery performance. Research and development of negative electrodes for sodium-ion batteries with high rate performance and high specific capacity have become a hot research field in recent years.

[0004] Antimony (tin)-based active materials have the significant advantage of high specific capacity, which can greatly improve the energy density of the battery and are preferred negative electrode materials for sodium-ion batteries. Antimony (tin) has become a sodium-ion battery negative electrode material with great application prospects due to its high theoretical specific capacity, small electrode polarization, appropriate Na + insertion / extraction potential, low price, and environmental friendliness. However, during the charge and discharge process, the antimony (tin)-based active materials will undergo huge volume changes, resulting in unstable material structures and rapid cycle attenuation, which restricts the development of high-energy-density sodium-ion batteries.

[0005] Nanostructuring the material can effectively reduce the internal stress of antimony (tin) during the charge and discharge process, and thus effectively reduce particle fragmentation. In addition, nanostructuring the material can also significantly shorten the diffusion distance of Na + ions, enhance the reaction kinetics, and improve the electrochemical performance.

[0006] Hou et al. (Sodium / lithium storage behavior of antimony hollow nanospheresfor rechargeable batteries[J]. ACS Applied Materials & Interfaces, 2014, 6(18): 16189-16196.) Prepared antimony hollow nanospheres (SbHNS) and antimony nanospheres (Sb NS) by a simple, low-cost and green electrogalvanic replacement method. The unique structure of this kind of hollow nanospheres not only alleviates the volume expansion problem of antimony during charge and discharge, but also increases the specific surface area of antimony, shortens the ion transport distance, and thus exhibits excellent electrochemical performance.

[0007] Furthermore, Liang et al. (Large-scale highly ordered Sb nanorod array anodes with high capacity and rate capability for sodium-ion batteries[J]. Energy & Environmental Science , 2015, 8(10): 2954-2962.) Synthesized an ordered antimony nanorod array with vertical arrangement and large spacing; Liu et al. (Galvanic replacement synthesis of highly uniform Sb nanotubes: reaction mechanism and enhanced sodium storage performance[J]. ACS nano , 2019, 13(5): 5885-5892.) Using Cu nanowires as templates, synthesized antimony nanotubes Sb-NTs by the template method; Lin et al. (A fast synthetic strategy for high-quality atomically thin antimonene with ultrahigh sonication power[J]. Nano Research , 2018, 11: 5968-5977.) Prepared high-quality few-layer antimonene with a thickness of about 0.5 nm by a fast and efficient liquid-phase exfoliation method. Its good conductivity and two-dimensional structure endow antimonene with more active sites for sodium storage, provide a convenient path for electron transfer and mass transfer, and can reduce the volume expansion during charge and discharge.

[0008] Nanomaterials have unique physical and chemical properties and show great application potential in the field of energy storage. However, they also have deficiencies in aspects such as aggregation and low density, specifically including:

[0009] Agglomeration problem: Nanomaterials have a very large specific surface area and surface energy, and are in an energy-unstable state. To reduce the surface energy, particles will attract each other and agglomerate. The agglomeration phenomenon will lead to a decrease in the effective specific surface area of nanomaterials, thereby reducing the contact area with the electrolyte and lowering the reaction activity of the electrode material. For example, in lithium-ion batteries, the agglomeration of nano-electrode materials will reduce the channels for lithium-ion insertion and extraction, lower the charge-discharge efficiency of the battery, and deteriorate the cycling performance. At the same time, agglomeration may also cause changes in the internal pore structure of the material, affecting the diffusion and transport of the electrolyte in the material and further hindering the charge-discharge process of the battery.

[0010] Low-density problem: Nanomaterials have small particle sizes, and the intermolecular forces between particles are relatively weak, making it difficult to form a closely packed structure. Therefore, they exhibit low density macroscopically. A lower density means that the mass of nanomaterials per unit volume is smaller, resulting in a decrease in the energy density of energy storage devices. Using low-density nano-electrode materials can store relatively less charge in the same volume, unable to meet some application scenarios with high requirements for energy density, such as electric vehicles and portable electronic devices. In addition, low density may also affect the mechanical properties of the material, making the electrode more prone to deformation or damage during charge and discharge, reducing the stability and service life of the energy storage device.

[0011] Combining antimony (tin)-based active materials with carbon materials to prepare composite materials is another effective method to solve the above problems. Carbon materials can not only improve the conductivity of the electrode but also alleviate the volume expansion of antimony (tin)-based active materials to a certain extent, greatly improving the electrochemical performance of the composite materials.

[0012] By surface coating the antimony material to reduce the direct contact between the electrolyte and antimony, a stable SEI film is formed, and the coating layer can provide a larger buffer space for the antimony material, thereby alleviating its volume expansion during the cycling process. Combining nano-antimony with a conductive matrix carbon can effectively buffer the huge volume expansion problem of the antimony negative electrode material, improve the stability and cycling life of the material, further provide a conductive channel for the antimony material, and enhance the electronic conductivity and ion diffusion kinetics of the material.

[0013] There are roughly two common methods for preparing antimony (tin)-based carbon nanocomposites. One is to first prepare a sol-gel body of antimony (tin)-based carbon nanomaterials by the sol-gel method, and then add purified carbon powder for carbonization treatment to prepare antimony (tin)-based carbon nanocomposites; the other is to use antimony (tin)-based compounds as precursors, mix them with carbon powder, and prepare antimony (tin)-based carbon nanocomposites through direct reaction.

[0014] Zhang et al. (Activation of electrochemical lithium and sodium storage of nanocrystalline antimony by anchoring on graphene via a facile in situ solvothermal route[J]. Journal of Power Sources , 2014, 247204-212.) prepared antimony / graphene nanocomposites using a simple solvothermal method. By uniformly dispersing antimony nanocrystals on graphene, the buffering, confinement, and conduction effects of graphene significantly improved the conductivity of antimony and enhanced the sodium storage performance of the material. Hu et al. (A chemically coupled antimony / multilayer graphene hybrid as a high-performance anode for sodium-ion batteries[J]. Chemistry of Materials , 27.23 (2015):8138-8145.) synthesized antimony / multilayer graphene (Sb-MLG) composites by uniformly anchoring antimony on multilayer graphene via chemical vapor deposition. Liu et al. (2D sandwich-like nanosheets of ultrafine Sb nanoparticles anchored to graphene for high-efficiency sodium storage. Nano Research , 10(2017): 4360-4367.) prepared a 2D sandwich-like graphene-supported antimony nanoparticle composite through a simple electrostatic assembly and reduction process, uniformly fixing ultrafine nano-ions on the surface of graphene sheets, which can minimize the agglomeration of antimony. Gu et al. (Liquid-phase exfoliated metallic antimony nanosheets toward high volumetric sodium storage. Advanced Energy Materials , 7.17(2017):1700447.) prepared an antimony / graphene hybrid membrane (SbNS-G) composed of ultrathin (~4 nm) and foldable metallic antimony nanosheets and graphene with adjustable density, where the large volume change of metallic antimony can be effectively alleviated with the help of flexible graphene.

[0015] However, in current composite materials, the antimony (tin)-based active material is simply distributed on the surface of the carbon material, and the problem of volume expansion of the antimony (tin)-based active material cannot be fully solved. The cycling performance of the composite material needs to be further improved. Moreover, most of the currently prepared composite materials are fluffy powders with very low bulk density, which cannot meet the requirements of high energy density. Therefore, there are still great challenges in designing and preparing high-density and long-life antimony (tin)-based carbon composite materials. Summary of the Invention

[0016] The object of the present invention is to provide an antimony (tin)-based / carbon microsphere composite material to solve the problems of relatively low density of the antimony (tin)-based material and large volume expansion during charge and discharge.

[0017] To achieve the above object of the invention, the present invention first provides an antimony (tin)-based / carbon microsphere composite material, which is composed of dense carbon microspheres as a matrix loaded with antimony (tin)-based nanoparticle active materials. The carbon microspheres have a particle size of 2-30 microns, and have nanopores on the surface and inside. The antimony (tin)-based nanoparticle active materials account for 55-75% of the total mass of the composite material and are uniformly dispersed in the nanopores of the carbon microspheres. The density of the antimony (tin)-based / carbon microsphere composite material is 3.0-4.5 g / cm 3 .

[0018] In the antimony (tin)-based / carbon microsphere composite material of the present invention, the carbon microspheres as the matrix have three functions: First, since the antimony (tin)-based nanoparticle active materials are loaded in the nanopores of the carbon microspheres, the carbon microspheres play a role of framework self-support; Second, the carbon microspheres have high conductivity, and the introduction thereof can improve the conductivity of the main body of the antimony (tin)-based nanoparticle active materials; Third, a large number of nanopores on the surface and inside of the carbon microspheres can effectively relieve the volume expansion of the antimony (tin)-based nanoparticle active materials during electrochemical charge and discharge.

[0019] The object of the present invention also lies in providing a preparation method for a high-density and high-performance antimony (tin)-based / carbon microsphere composite material. The preparation method has rich raw materials, low cost, good repeatability, and is easy to achieve the purpose of large-scale production.

[0020] The preparation method of the antimony (tin)-based / carbon microsphere composite material provided by the present invention is to disperse an antimony (tin) source, a carbon source and a graphene material in water to obtain a uniform solution, atomize it and spray it into a high-temperature oil bath to form a composite microsphere precursor material, and perform high-temperature carbonization in an inert atmosphere to obtain the antimony (tin)-based / carbon microsphere composite material.

[0021] Furthermore, the preparation method of the antimony (tin)-based / carbon microsphere composite material of the present invention specifically includes:

[0022] Disperse the antimony (tin) source and the carbon source in water, with or without adding conductive carbon materials, and ultrasonically stir and mix to obtain a homogeneous solution;

[0023] Use an atomization device to atomize the above homogeneous solution and then spray it into a high-temperature oil bath;

[0024] After filtration, washing, and drying, a composite microsphere precursor material is obtained;

[0025] Carry out high-temperature calcination and carbonization of the composite microsphere precursor material under the protection of an inert atmosphere, and after cooling, an antimony (tin)-based / carbon microsphere composite material is obtained.

[0026] The preparation method of the present invention uniformly composes the antimony (tin) source in the carbon material by a spraying method, obtaining a microsphere composite of micron size. Then, antimony (tin) nanoparticles are in-situ generated by high-temperature carbonization and uniformly dispersed in the carbon microsphere matrix, forming a high-density antimony (tin)-based / carbon microsphere composite material.

[0027] As a preferred scheme, the antimony (tin) source is mainly used to provide metal antimony (tin) ions. Therefore, any easily ionizable antimony (tin) source can meet the usage requirements of the present invention.

[0028] More preferably, the antimony source includes but is not limited to potassium antimonyl tartrate or antimony chloride, and the tin source includes but is not limited to any one of stannous chloride, tin tetrachloride, dimethyldichlorotin, or triphenyltin chloride.

[0029] As a preferred scheme, the carbon source can be any common carbon-based material in the art that can form carbon microsphere materials after carbonization, so as to achieve the purpose of improving the electrochemical activity of the electrode material, and can include but is not limited to at least one of sucrose, starch, polyvinylpyrrolidone, polyvinyl alcohol, or glucose.

[0030] More preferably, the carbon source is sucrose or glucose.

[0031] As a preferred scheme, the mass ratio of the carbon source to the antimony (tin) source is 1:(2 - 5).

[0032] As a preferred scheme, the conductive carbon material is any one or several of graphene, carbon nanotubes, or nanofibers, and its addition amount is 0.5 - 3.5% of the mass of the carbon source.

[0033] As a preferred scheme, the atomization device can be any device capable of atomizing liquids. In the present invention, a nano-sprayer is more preferably used.

[0034] As a preferred scheme, the oil medium used in the high-temperature oil bath is olive oil or silicone oil, and the temperature of the high-temperature oil bath is 150 - 200 °C.

[0035] As a preferred embodiment, the atomization rate is set to 2-20 mL / min. The conditions during the spraying process will affect the morphology of the formed carbon microsphere composite material, and the best morphology is obtained under the preferred conditions.

[0036] As a preferred embodiment, the temperature of the high-temperature calcination is 700-1300 °C, and the calcination time is 1-5 h.

[0037] Furthermore, the preparation method of the antimony (tin)-based / carbon microsphere composite material of the present invention further includes further performing selenization (sulfurization / phosphorization) treatment on the antimony (tin) / carbon microsphere composite material to prepare a selenium-antimony (tin) / carbon microsphere composite material or a sulfur-antimony (tin) / carbon microsphere composite material or a phosphorus-antimony (tin) / carbon microsphere composite material.

[0038] As a preferred embodiment, the selenization (sulfurization / phosphorization) treatment is specifically to place the prepared antimony (tin) / carbon microsphere composite material in the center of a tube furnace, place the volatile selenium (sulfur / phosphorus) source upstream of the tube furnace, and perform selenization (sulfurization / phosphorization) treatment by heating under an inert atmosphere condition, and obtain a selenium-antimony (tin) / carbon microsphere composite material or a sulfur-antimony (tin) / carbon microsphere composite material or a phosphorus-antimony (tin) / carbon microsphere composite material after cooling.

[0039] As a preferred embodiment, the mass ratio of the selenium (sulfur / phosphorus) source to the antimony (tin)-based / carbon microsphere composite material is (2-8):1.

[0040] As a preferred embodiment, the selenization (sulfurization / phosphorization) treatment temperature is 300-600 °C, and the treatment time is 1-6 h.

[0041] As a preferred embodiment, the selenium source of the volatile selenium-containing material is selenium powder, the sulfur source of the volatile sulfur-containing material is any one of thiourea or sulfur powder, and the phosphorus source of the volatile phosphorus-containing material is any one of sodium dihydrogen phosphate or sodium hypophosphite.

[0042] As a more preferred embodiment, the specific conditions of the selenization treatment are using selenium powder as the selenium source, with a mass ratio of selenium powder to the antimony (tin)-based / carbon microsphere composite material of 2:1, and performing selenization treatment at 500 °C for 2 h under a protective atmosphere. If the selenization temperature is too low, it is likely to cause incomplete selenization, and if it is too high, it is likely to cause volatilization loss of selenium powder, making it difficult to achieve the purpose of efficient selenization.

[0043] As a more preferred embodiment, the specific conditions of the sulfurization treatment are using thiourea as the sulfur source, with a mass ratio of thiourea to the antimony (tin)-based / carbon microsphere composite material of 6:1, and performing sulfurization treatment at 500 °C for 5 h under a protective atmosphere.

[0044] The third object of the present invention is to provide an application of an antimony (tin)-based / carbon microsphere composite material. By using the composite material as the anode material of a sodium-ion battery, a sodium-ion battery with good cycle stability and high specific capacity can be obtained.

[0045] The antimony (tin)-based / carbon microsphere composite material prepared by the present invention is composed of carbon microspheres and antimony (tin)-based active components. Among them, the active antimony (tin)-based nanoparticles are confined in the carbon microspheres, which can effectively alleviate the volume expansion of the active components caused by the insertion and extraction of sodium ions, greatly improving the cycle performance and service life of the material. Moreover, the carbon microspheres themselves have high conductivity. As a good conductive carrier, the antimony (tin)-based active material grows in-situ on its surface and inside, greatly improving the structural stability of the antimony (tin)-based active material and improving the conductivity of the antimony (tin)-based active components.

[0046] Based on the unique volume effect, confinement effect and interfacial characteristics of the antimony (tin)-based / carbon microsphere composite material of the present invention, the electrochemical performance of the composite material can be effectively improved. When it is used as the anode material of a sodium-ion battery, it exhibits advantages such as high specific capacity and good cycle stability.

[0047] The antimony (tin)-based / carbon microsphere composite material prepared by the present invention not only has a high density, but also has the advantages of low cost and good repeatability in the preparation method. Description of the Drawings

[0048] Figure 1 is the scanning electron microscope image of the tin / carbon microsphere composite material prepared in Example 1.

[0049] Figure 2 is the cycle performance graph of the sodium-ion battery based on the tin / carbon microsphere composite material in Example 1.

[0050] Figure 3 is the scanning electron microscope image of the antimony / carbon microsphere composite material prepared in Example 2.

[0051] Figure 4 is the transmission electron microscope image of the antimony / carbon microsphere composite material prepared in Example 2.

[0052] Figure 5 is the X-ray diffraction pattern of the antimony / carbon microsphere composite material prepared in Example 2.

[0053] Figure 6 is the cycle performance graph of the sodium-ion battery based on the antimony / carbon microsphere composite material in Example 2.

[0054] Figure 7 is the X-ray diffraction pattern of the antimony selenide / carbon microsphere composite material prepared in Example 3.

[0055] Figure 8It is the cycling performance graph of the sodium-ion battery based on the antimony selenide / carbon microsphere composite material of Example 3.

[0056] Figure 9 It is the scanning electron microscope image of the antimony sulfide / carbon microsphere composite material prepared in Example 4.

[0057] Figure 10 It is the X-ray diffraction pattern of the antimony sulfide / carbon microsphere composite material prepared in Example 4.

[0058] Figure 11 It is the scanning electron microscope image of the antimony / carbon composite material prepared in the comparative example.

[0059] Figure 12 It is the cycling performance graph of the sodium-ion battery based on the antimony / carbon composite material of the comparative example. Embodiment

[0060] The following further describes in detail the specific embodiments of the present invention in conjunction with the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, so that those skilled in the art can well understand and utilize the present invention, rather than limiting the protection scope of the present invention.

[0061] The production processes, experimental methods or detection methods involved in the embodiments of the present invention are all conventional methods in the prior art without special instructions, and their names and / or abbreviations are all conventional names in the field, and are very clear and definite in the relevant application fields. Those skilled in the art can understand the conventional process steps according to the name and apply the corresponding equipment, and implement them according to the conventional conditions or the conditions recommended by the manufacturer.

[0062] There are no special restrictions on the sources of various instruments, equipment, raw materials or reagents used in the embodiments of the present invention. They are all conventional products that can be obtained through regular commercial channels, and can also be prepared according to the conventional methods well-known to those skilled in the art. Example

[0063] Example 1

[0064] Disperse 30 mg of graphene in 50 mL of deionized water and ultrasonicate for 3 h to obtain a homogeneous solution.

[0065] Add 1 g of sucrose and 3 g of stannous chloride to the above homogeneous solution and stir for 10 h to obtain a homogeneous mixed solution.

[0066] Transfer the above mixed solution to a nano spray gun, spray it into olive oil heated to 160 °C, centrifuge to collect the precursor material, wash it several times with petroleum ether and absolute ethanol, and then place it in a vacuum drying oven and dry at 80 °C for 4 h.

[0067] The dried precursor material was placed in a tube furnace, heated to 700°C at a rate of 3°C / min in an argon atmosphere, and carbonized at a constant temperature for 2 hours to prepare a carbon microsphere (tin / carbon microsphere) composite material loaded with tin nanoparticles.

[0068] Figure 1 A scanning electron microscope image of the tin / carbon microsphere composite material is given. It can be seen from the image that the tin / carbon microspheres are round spheres with a diameter of 3 to 12 microns.

[0069] The true density of the prepared tin / carbon microsphere composite material was tested by helium replacement method and was 3.5 g / cm 3 .

[0070] The tin / carbon microsphere composite material was used as the negative electrode material to assemble a CR2032 button-type sodium ion battery in an inert gas glove box.

[0071] The tin / carbon microsphere composite material, PVDF, and Super P conductive agent were dispersed in N-methylpyrrolidone (NMP) at a mass ratio of 8:1:1 to form a uniform slurry, coated on copper foil, dried at 80°C in a vacuum drying oven for 12 h, cut into discs with a diameter of 12 mm as the working electrode, metallic sodium as the comparison electrode, and glass fiber (Whatman) as the diaphragm. After the electrolyte was injected, it was assembled into a CR2032 button-type sodium-ion battery under a pressure of 10 MPa.

[0072] The assembled button-type sodium ion battery was subjected to electrochemical performance tests such as constant current charge and discharge and cycle stability. Figure 2 As shown, at 0.1A g -1 After 100 cycles at the current density, the battery capacity retention rate is 97.5% and the coulombic efficiency is close to 100%.

[0073] Example 2

[0074] 20 mg of carbon nanotubes were dispersed in 50 mL of deionized water and ultrasonicated for 3 h to obtain a uniform solution.

[0075] 1 g of starch and 5 g of potassium antimony tartrate were added to the above uniform solution and stirred for 10 h to obtain a uniform mixed solution.

[0076] The mixed solution was transferred to a nano spray gun and sprayed into olive oil heated to 180°C. The precursor material was collected by centrifugation, washed several times with petroleum ether and anhydrous ethanol, and then placed in a vacuum drying oven and dried at 80°C for 4 hours.

[0077] The dried precursor material was placed in a tube furnace, heated to 800°C at a rate of 3°C / min in an argon atmosphere, and carbonized at a constant temperature for 2 hours to prepare a carbon microsphere (antimony / carbon microsphere) composite material loaded with antimony nanoparticles.

[0078] Figure 3 It is the scanning electron microscope image of the above-mentioned antimony / carbon microsphere composite material. It can be seen from the figure that the antimony / carbon microspheres are spherical in shape, with a sphere diameter of 5-20 microns.

[0079] The true density of the prepared antimony / carbon microsphere composite material was measured by the helium replacement method to be 4.5 g / cm 3 .

[0080] Figure 4 In the transmission electron microscope image of the provided antimony / carbon microsphere composite material, not only does it show that the product is microspherical, but also a large number of nanopores can be observed inside the spheres.

[0081] Figure 5 It is the X-ray diffraction pattern of the above-prepared antimony / carbon microsphere composite material. It can be seen that the diffraction peaks of the product are in good agreement with the standard diffraction peaks of antimony, proving the successful preparation of antimony.

[0082] Using the above-mentioned antimony / carbon microsphere composite material as the negative electrode material, according to the method in Example 1, a CR2032-type button sodium-ion battery was assembled in an inert gas glove box, and electrochemical performance tests such as constant current charge and discharge and cycle stability were carried out. The results are as Figure 6 shown. At a large current density of 1 A g -1 , after 750 cycles, a capacity of 267.8 mAh g -1 can still be maintained.

[0083] Example 3

[0084] Weigh 100 mg of the antimony / carbon microsphere composite material prepared in Example 2 and 200 mg of selenium powder, mix and grind them evenly in an agate mortar, place them in a tube furnace, and heat them to 500 °C at a rate of 2 °C / min in an argon atmosphere, and keep the temperature for seleniumization for 2 h to prepare a seleniumized antimony / carbon microsphere composite material.

[0085] The true density of the prepared seleniumized antimony / carbon microsphere composite material was measured by the helium replacement method to be 4.1 g / cm 3 .

[0086] Figure 7 It is the X-ray diffraction pattern of the above-prepared seleniumized antimony / carbon microsphere composite material. It can be seen that the diffraction peaks of the product are in good agreement with the standard diffraction peaks of seleniumized antimony, proving the successful preparation of seleniumized antimony.

[0087] Using the above-mentioned seleniumized antimony / carbon microsphere composite material as the negative electrode material, according to the method in Example 1, a CR2032-type button sodium-ion battery was assembled in an inert gas glove box, and the electrochemical performance of the sodium-ion battery was tested. The results are as Figure 8 shown. At 0.5 A g -1At a current density, the capacity after 100 cycles can be maintained at 325.6 mAh g -1 .

[0088] Example 4

[0089] Weigh 100 mg of the antimony / carbon microsphere composite material prepared in Example 2 and 800 mg of thiourea, place them in two crucibles, and put them in a tube furnace. Among them, thiourea is placed at the upwind, and the composite material is placed at the downwind, with a spacing of 5 cm. Heat it to 600 °C at a rate of 5 °C / min in an argon atmosphere and keep it at a constant temperature for sulfurization for 6 h to prepare a antimony sulfide / carbon microsphere composite material.

[0090] Figure 9 is the scanning electron microscope image of the above-prepared antimony sulfide / carbon microsphere composite material. It can be seen from the figure that the composite material is microspherical, and it can be seen from the broken part that there are a large number of nanopores inside the sphere.

[0091] The true density of the prepared antimony sulfide / carbon microsphere composite material was measured by the helium replacement method to be 3.8 g / cm 3 .

[0092] Figure 10 Further, the X-ray diffraction pattern of the composite material is given. It can be seen that the diffraction peaks of the product are in good agreement with the standard diffraction peaks of antimony sulfide, proving the successful preparation of antimony sulfide.

[0093] Using the above antimony sulfide / carbon microsphere composite material as the negative electrode material, according to the method in Example 1, assemble a CR2032 type button sodium ion battery in an inert gas glove box and conduct electrochemical performance tests on the sodium ion battery. At 0.5 A g -1 current density, the capacity can be maintained at 353.9 mAh g after 100 cycles -1 ; furthermore, the test results of the rate performance show that at 0.05, 0.1, 0.2, 0.5, 1.0, and 2.0 A g -1 current density, its reversible specific capacities are 570.3, 510.0, 452.6, 402.4, 364.2, and 321.1 mAh g -1 .

[0094] Comparative Example

[0095] Weigh 5 g of potassium antimonyl tartrate and place it in a tube furnace. Heat it to 800 °C at a rate of 3 °C / min in an argon atmosphere and keep it at a constant temperature for carbonization for 2 h to prepare an antimony / carbon (Sb / C) composite material loaded with antimony nanoparticles.

[0096] From Figure 11As can be seen from the scanning electron microscope images, the antimony / carbon composite material exhibits an irregular morphology, and a large number of antimony particles are significantly exposed on the surface of the carbon matrix, failing to be effectively coated or dispersed by the carbon material, and the carbon matrix fails to form a continuous and uniform coating layer, resulting in the easy direct contact between the antimony particles and the electrolyte during charge and discharge processes.

[0097] Using the above antimony / carbon composite material as the anode material, a CR2032 type button sodium-ion battery was assembled in an inert gas glove box according to the method in Example 1, and the electrochemical performance of the sodium-ion battery was tested.

[0098] As Figure 12 shown, at a current density of 0.5 A g -1 , the specific capacity after 150 cycles is 181 mAh g -1 , and the capacity retention rate is only 39.7%.

[0099] The above embodiments of the present invention do not describe all the details in detail, nor do they limit the present invention to the above-described embodiments. Various changes, modifications, substitutions, and variations made to these embodiments by those of ordinary skill in the art without departing from the principles and purposes of the present invention shall be included within the protection scope of the present invention.

Claims

1. An antimony (tin)-based / carbon microsphere composite material, which is composed of dense carbon microspheres as a matrix and loaded with antimony (tin)-based nanoparticle active materials. The carbon microspheres have a particle size of 2 to 30 microns and have nanopores on the surface and inside. The antimony (tin)-based nanoparticle active materials account for 55 to 75% of the total mass of the composite material and are uniformly dispersed in the nanopores of the carbon microspheres. The density of the antimony (tin)-based / carbon microsphere composite material is 3.0 to 4.5 g / cm 3 .

2. The method for preparing the antimony (tin)-based / carbon microsphere composite material according to claim 1, comprising: Dispersing the antimony (tin) source and the carbon source in water, adding or not adding a conductive carbon material, and mixing by ultrasonic stirring to obtain a uniform solution; The uniform solution is atomized by an atomizing device and then sprayed into a high-temperature oil bath; After filtering, washing and drying, a composite microsphere precursor material is obtained; The composite microsphere precursor material is calcined and carbonized at high temperature under the protection of an inert atmosphere, and then cooled to obtain an antimony (tin)-based / carbon microsphere composite material.

3. The method for preparing the antimony (tin)-based / carbon microsphere composite material according to claim 2, characterized in that The antimony source is potassium antimony tartrate or antimony chloride, and the tin source is any one of stannous chloride, tin tetrachloride, dimethyltin dichloride or triphenyltin chloride.

4. The method for preparing the antimony (tin)-based / carbon microsphere composite material according to claim 2, characterized in that The carbon source is at least one of sucrose, starch, polyvinyl pyrrolidone, polyvinyl alcohol or glucose.

5. The method for preparing the antimony (tin)-based / carbon microsphere composite material according to claim 2, characterized in that The mass ratio of the carbon source to the antimony (tin) source is 1:(2-5).

6. The method for preparing the antimony (tin)-based / carbon microsphere composite material according to claim 2, characterized in that The conductive carbon material is any one or more of graphene, carbon nanotubes or nano-carbon fibers, and the added amount thereof is 0.5-3.5% of the mass of the carbon source.

7. The method for preparing the antimony (tin)-based / carbon microsphere composite material according to claim 2, characterized in that The high temperature oil bath uses olive oil or silicone oil, and the oil bath temperature is 150-200°C.

8. The method for preparing the antimony (tin)-based / carbon microsphere composite material according to claim 2, characterized in that The high temperature calcination temperature is 700-1300° C., and the calcination time is 1-5 hours.

9. The method for preparing the antimony (tin)-based / carbon microsphere composite material according to claim 2, characterized in that The invention also includes the step of selenizing (sulfurizing / phosphating) the antimony (tin) / carbon microsphere composite material with a volatile selenium (sulfur / phosphorus) source to prepare an antimony (tin) selenide / carbon microsphere composite material or an antimony (tin) sulfide / carbon microsphere composite material or an antimony (tin) phosphide / carbon microsphere composite material.

10. Use of the antimony (tin)-based / carbon microsphere composite material according to claim 1 as a negative electrode material for sodium ion batteries.

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