Single-element antimony, and a preparation method and application thereof

Abstract

The application relates to the field of secondary batteries, in particular to a single-element antimony as well as a preparation method and application thereof, which comprises the following steps: configuring an antimony salt solution containing a complexing agent; immersing a base of a lively metal into the antimony salt solution to perform a displacement reaction, wherein the standard electrode potential of the lively metal is lower than that of Sb 3+ / Sb; taking out the base of the lively metal, scraping a surface product, washing the surface product with hydrochloric acid and then washing the surface product with deionized water, and finally vacuum drying, so that the method is mild, simple, green and environment-friendly, is easy to scale up, and provides a brand-new scheme for practicalization of a high-performance alloy type sodium storage negative electrode material.

Description

Technical Field

[0001] This invention relates to the field of secondary batteries, specifically to elemental antimony, its preparation method, and its applications. Background Technology

[0002] With the transformation of the global energy structure and the urgent need for efficient storage of renewable energy, electrochemical energy storage technology has become a key cornerstone supporting the sustainable development of modern society. Among numerous energy storage devices, lithium-ion batteries have achieved tremendous commercial success in portable electronic devices and electric vehicles due to their high energy density and long cycle life. However, the limited global reserves and uneven geographical distribution of lithium resources have led to a continuous increase in raw material costs, making it difficult to simultaneously support the parallel development of both electric vehicles and large-scale stationary energy storage industries. Against this backdrop, sodium-ion batteries, with their core advantages such as extremely abundant sodium resources, low cost, and similar electrochemical energy storage mechanisms to lithium-ion batteries, are considered one of the most promising alternative technologies for large-scale energy storage systems.

[0003] As a key component of sodium-ion batteries, the performance of the anode material directly determines the overall energy density, rate performance, and cycle life of the battery. Currently, hard carbon materials are the most widely studied and commercially promising anode materials, exhibiting stable structure and excellent cycle performance. However, the reversible specific capacity of hard carbon materials is approaching its theoretical limit, leaving limited room for improvement. Furthermore, its extremely low sodium intercalation potential makes it prone to sodium dendrite formation under high-rate or overcharge conditions, posing serious safety hazards. Therefore, developing novel anode materials that combine high specific capacity with excellent safety has significant scientific importance and immense industrial value.

[0004] Among numerous candidate materials, metallic anode materials, especially antimony, are considered one of the most promising choices. Antimony's theoretical sodium storage capacity is far higher than that of hard carbon materials, ensuring a higher overall battery operating voltage while effectively avoiding sodium dendrite formation, resulting in better safety. Furthermore, the sodium insertion / extraction reaction of antimony is highly reversible, and its electrochemical reaction process is similar to that of antimony-based anodes in lithium-ion batteries, both involving multi-step alloying reactions. However, antimony faces a critical bottleneck on its path to practical application: a significant volume effect. During sodium ion insertion to form an alloy, antimony particles experience a volume expansion of up to approximately 300%. Conversely, during sodium extraction, a corresponding dramatic volume contraction occurs. This repeated, massive volume stress rapidly leads to the fragmentation of the electrode material during cycling, causing loss of electrical contact between the active material and the current collector and conductive network, resulting in rapid capacity decay. Simultaneously, the repeatedly exposed fresh electrode surface continuously consumes electrolyte, generating an excessively thick and unstable solid electrolyte interface film, leading to low coulombic efficiency and a sharp increase in interfacial impedance, ultimately causing battery failure.

[0005] Constructing a nanoscale pore network within antimony particles allows for pre-planning of space for volume expansion. When antimony undergoes an alloying reaction with sodium, resulting in volume increase, the particles expand into the internal pores rather than being squeezed outwards into the electrode space. This significantly mitigates the overall macroscopic volume change, ensuring the integrity of the electrode structure and cycling stability. Current techniques often employ acid treatment of antimony alloys to prepare porous elemental antimony. This method has several drawbacks: First, it requires large quantities of acid, posing environmental risks and corroding equipment. Second, it generates explosive hydrogen gas, posing a certain danger. Third, the limited contact area with the acid results in poor uniformity of the porous structure, leading to poor cycling stability of the prepared antimony-based anode material. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects and shortcomings of existing technologies and provide elemental antimony, its preparation method, and its applications. The core innovations and technical solutions of this invention mainly include the following aspects: This invention first provides elemental antimony, in which the elemental antimony exhibits a three-dimensional, interconnected nanoporous structure within a single particle. This porous structure is fundamentally different from pores formed only by surface pits or simple particle stacking. It means that there is a continuous nanochannel network inside the particle, connected to the outer surface, which can provide a pathway for rapid mass transfer of sodium ions and reserve internal buffer space for huge volume expansion.

[0007] To obtain the aforementioned unique structure of elemental antimony, this invention also provides a preparation method. The core of this method lies in using a functionalized ionic liquid with a specific structure as a complexing agent in a liquid environment to in-situ deposit elemental antimony with a nanoporous structure on an active metal substrate via a displacement reaction. The method specifically includes the following steps: (1) Dissolve the antimony salt in a suitable solvent and add a specific amount of phosphonic imidazole ionic liquid as a complexing agent. Stir until completely dissolved to form a uniform and transparent reaction solution. (2) Surface activation treatment is performed on the active metal substrate (such as zinc foil) to remove the surface oxide layer and contaminants, so as to expose the highly active fresh metal surface; (3) The pretreated active metal substrate is completely immersed in the reaction solution prepared in step (1), and a liquid-phase displacement reaction is carried out under stirring and at a certain temperature. Since the standard electrode potential of the active metal is much lower than that of Sb... 3+ / Sb, the base metal undergoes oxidation and dissolution, releasing electrons. Antimony ions in the solution capture electrons and are reduced to metallic antimony, which is then deposited on the base surface.

[0008] In this process, the complexing agent in the electrolyte coordinates with antimony ions through its specific functional groups and selectively adsorbs and regulates antimony atoms / nuclei in the early stage of deposition, inducing antimony atoms to assemble and grow in a specific, non-dense stacking manner, thereby directly constructing a special structure with internally interconnected nanopores in one step. (4) After the reaction is complete, the substrate is removed and the deposited products generated on the surface are collected by physical scraping. The obtained powder is first washed with dilute hydrochloric acid to dissolve and remove trace amounts of active metal impurities that may be mixed or co-deposited. Then it is repeatedly washed with deionized water and ethanol until the washing waste liquid is neutral. Finally, it is dried under vacuum to obtain the elemental antimony powder with nanoporous structure.

[0009] The essence of this invention lies in the complexing agent used. This complexing agent is a novel type of phosphonate-based imidazole ionic liquid, characterized by a cationic structure comprising an imidazole cationic head group, which is connected to a phosphorous functional group via an alkylene "bridging" group. Its general cationic structural formula can be illustrated as follows: ; Wherein, L is a straight-chain or branched alkylene group of C1-C6, such as methylene, ethylene, propylene, etc.; R is an alkyl group of C1-C8, such as methyl, ethyl, butyl, etc.

[0010] In stark contrast, conventional ionic liquids, such as 1-ethyl-3-methylimidazolium chloride, have only simple alkyl chains attached to their imidazole cations, lacking functional groups capable of specific and strong interactions with metal ions and metal surfaces. The ionic liquid designed in this invention possesses a highly effective coordination ability with its phosphite group, forming stable chelates or bridging complexes with antimony ions. This alters the reduction potential and electrocrystallization behavior of antimony ions, acting as a "soft template" or "structure guide," inducing antimony atoms to assemble and grow in a specific, non-dense packing manner. Simultaneously, this ionic liquid may also undergo specific adsorption on the surface of newly formed antimony crystals, inhibiting the preferential growth of certain crystal faces and promoting isotropic porous growth. This regulatory effect based on specific coordination chemistry and surface adsorption is the fundamental guarantee for constructing uniform, interconnected porous nanostructures.

[0011] This invention further provides an application scheme for using the above-mentioned nanoporous elemental antimony in the anode active material of sodium-ion batteries. To construct a high-performance, long-cycle anode, this invention employs sulfur-doped carbon nanotubes as a conductive buffer framework.

[0012] Multi-walled carbon nanotubes (MWCNTs) have an inert surface with few defects, and their bonding with antimony is limited to weak van der Waals forces. This invention introduces sulfur heteroatoms into the carbon lattice of MWCNTs through high-temperature in-situ sulfur doping. This not only significantly increases the number of surface defect sites and active sites, improving their sodium ion storage capacity, but more importantly, the introduction of sulfur atoms alters the electron cloud distribution and chemical activity of the MWCNT surface, greatly enhancing the chemical affinity and interfacial bonding strength between the MWCNTs and antimony nanoparticles, and tending to form Sb-SC bridge interfaces during heat treatment.

[0013] On the other hand, this invention employs ball milling composite and low-temperature heat treatment. Nanoporous elemental antimony and sulfur-doped carbon nanotubes are mixed and initially composited in a liquid medium (such as ethanol) at an optimized mass ratio through ball milling. This process aims to uniformly anchor and embed the antimony nanoparticles into the three-dimensional network formed by the interwoven sulfur-doped carbon nanotubes, achieving a tight bond. Following this, a heat treatment process is performed under an inert atmosphere. This crucial step promotes localized thermochemical reactions between the antimony and sulfur-doped carbon nanotube surfaces, transforming the originally physically contacted interface into a chemically bonded interface, thereby significantly improving the integrity of the composite structure and its durability under cyclic stress.

[0014] The above methods ultimately achieved an extremely high capacity retention rate for sodium-ion battery anode materials under long-term cycling.

[0015] Preferably, the active metal substrate is selected from at least one of zinc, iron, aluminum, magnesium, and manganese, or from an alloy containing the above metals as the main components.

[0016] These metals were chosen because their standard electrode potentials are all much lower than antimony, enabling them to undergo thermodynamically spontaneous displacement reactions. Different substrate metals have different displacement rates, surface morphologies, and costs. For example, zinc foil was chosen as the optimal substrate in the examples due to its moderate electrode potential, controllable reaction rate, and loose, easily scraped product. Iron and aluminum are also suitable because they are more widely available and extremely inexpensive, but aluminum surfaces require pre-activation by removing stubborn oxide films. Magnesium and manganese have even lower potentials, stronger reaction driving forces, faster deposition rates, and may yield finer nanocrystalline structures. Using alloys containing these metals allows for adjustment of reactivity and deposition layer adhesion.

[0017] Preferably, the active metal substrate is in the form of foil, sheet, plate, or film.

[0018] Processing the substrate into these two-dimensional shapes with high specific surface area is beneficial to increasing the reaction interface area and improving the efficiency of the displacement reaction; it also makes the deposition layer grow uniformly, which is easy to scrape and collect later, and reduces dead corners and uneven deposition.

[0019] Preferably, the active metal substrate is pre-activated with hydrochloric acid.

[0020] Reactive metals may form a dense or porous oxide film on their surface in air, severely affecting the uniformity and rate of the displacement reaction. Pre-activation by immersion in dilute hydrochloric acid (e.g., 0.1-1 mol / L) effectively removes the surface oxide layer and contaminants, exposing a highly reactive, fresh surface to the metal substrate. The activation process takes only tens of seconds. The activated substrate should be immediately rinsed with deionized water, dried (either by wiping or air-drying), and then quickly immersed in the reaction solution to prevent re-oxidation. This pretreatment step is a crucial process detail for ensuring the uniformity and repeatability of the porous antimony deposition layer.

[0021] This invention also provides an application of elemental antimony in the negative electrode active material of sodium-ion batteries.

[0022] The interconnected nanopores within elemental antimony provide it with a self-buffering capacity for volume expansion. When used as an anode active material in sodium-ion batteries, during sodium intercalation, the material expands into the pores, maintaining the relatively stable external dimensions of individual particles, thereby preserving the overall structural integrity of the electrode and the conductive contact between particles. Therefore, the elemental antimony described in this invention is an ideal high-performance sodium storage anode active material, and can also be used in alkali metal ion batteries such as lithium-ion batteries and potassium-ion batteries.

[0023] Preferably, the sodium-ion battery negative electrode active material further includes carbon nanotubes.

[0024] Although the elemental antimony of this invention already possesses a nanoporous buffer structure, a synergistic enhancement effect can be achieved when it is further composited with conductive carbon-based materials. In particular, carbon nanotubes, due to their one-dimensional tubular structure, ultra-high aspect ratio, and excellent conductivity, can interweave to form a three-dimensional continuous conductive network in the electrode, tightly connecting the antimony particles. Simultaneously, the carbon nanotube network possesses excellent flexibility and strength, serving as an "exoskeleton" to further absorb and disperse stress generated by volume changes, preventing particle aggregation.

[0025] Preferably, the carbon nanotubes are treated with sulfur doping.

[0026] The near-perfect sp surface of the original carbon nanotubes 2Carbon nanotubes have a high degree of chemical inertness, and their bonding with antimony particles relies solely on van der Waals forces, resulting in limited interfacial strength. This invention achieves in-situ sulfur doping by subjecting carbon nanotubes to high-temperature treatment in a sulfur-containing atmosphere. Sulfur atoms are embedded in the carbon lattice in the form of CSC / S=C bonds, breaking the perfect structure of the carbon nanotubes and introducing a large number of defect sites and polar functional groups. This treatment brings three benefits: (1) the surface active sites and defects increase the adsorption and storage of sodium ions, contributing additional capacity; (2) the sulfur-containing functional groups may form strong CS-Sb chemical bonding anchors with antimony nanoparticles during heat treatment, greatly enhancing the interfacial bonding force between the two phases; (3) the higher degree of disorder in the carbon nanotubes makes them more flexible and enhances their buffering capacity.

[0027] The present invention also provides a negative electrode material composed of the above-mentioned elemental antimony and sulfur-doped carbon nanotubes.

[0028] Preferably, the mass ratio of elemental antimony to sulfur-doped carbon nanotubes is 1-4:1-4.

[0029] The mass ratio of elemental antimony to sulfur-doped carbon nanotubes can be 1:1, 1:2, 1:3, 1:4, 2:1, 3:1, or 4:1. These ratios are merely examples to facilitate understanding of the technical solution of this invention and are not intended as limitations.

[0030] Preferably, the preparation method of the above-mentioned sulfur-doped carbon nanotubes is as follows: The reaction can be carried out by reacting sulfur oxide gas with carbon material at a temperature of 600℃-1000℃ for 10min-300min.

[0031] Preferably, the preparation method of the above-mentioned negative electrode material is as follows: Using anhydrous ethanol as the ball milling medium, elemental antimony and sulfur-doped carbon nanotubes were mixed and ball-milled, then vacuum dried and heat-treated under argon protection.

[0032] Preferably, the heat treatment temperature is 300-500℃.

[0033] Antimony is a typical chalcophile element, exhibiting a very strong chemical affinity for sulfur. This invention utilizes a high-temperature SO2 atmosphere to treat multi-walled carbon nanotubes, covalently doping sulfur atoms into the sp atoms of carbon in the forms of CSC and C=S. 2Lattice defect sites. Under the thermal drive of heat treatment, the CSC / S=C bonds at these edges or defects are relatively active and exhibit a certain degree of reactivity. When zero-valent antimony atoms on the surface of nanoporous antimony particles come into close contact with these functional sulfur sites, a reaction may occur to form CS-Sb bonds. These strong chemical bonds act like countless "rivets," locking the antimony nanoparticles onto the three-dimensional conductive network of sulfur-doped carbon nanotubes. Even when sodium intercalation causes volume expansion, as long as these chemical anchors are not completely destroyed, the antimony particles can always maintain effective electronic contact with the conductive framework, thus exhibiting extremely excellent long-term cycling stability on a macroscopic scale.

[0034] It should be noted that the above-mentioned mechanism of action is a theoretical explanation based on the experimental phenomena of this invention. The accuracy of this theoretical explanation does not affect the inventiveness of the technical solution of this invention or the scope of patent protection.

[0035] Compared with the prior art, the present invention has the following advantages: This invention utilizes a phosphonate-based imidazolium ionic liquid with a specific structure as a complexing agent to perform a liquid-phase displacement reaction on an active metal substrate. For the first time, a one-step method at room temperature is used to directly prepare elemental antimony with a high specific surface area and three-dimensional interconnected nanopores within the particles. This structure provides an ideal internal buffer space for the significant volume expansion during sodium intercalation, fundamentally overcoming the problem of pulverization and deactivation caused by volume effects in traditional antimony-based materials. Simultaneously, by ball milling and combining the aforementioned elemental antimony with high-temperature in-situ sulfur-doped multi-walled carbon nanotubes followed by low-temperature heat treatment, the sulfur affinity of antimony is utilized to induce the formation of stable CS-Sb chemical bonds at the interface, firmly anchoring the antimony particles within the three-dimensional conductive network. This upgrades the relationship between the active material and the conductive framework from physical contact to chemical bonding, thereby ensuring high reversible specific capacity while endowing the anode material with cycling stability at high current densities. This method is mild, simple, environmentally friendly, and easily scalable, providing a novel solution for the practical application of high-performance alloy-based sodium storage anode materials. Attached Figure Description

[0036] Figure 1 This is a SEM image of elemental antimony prepared in Example 1.

[0037] Figure 2 This is a TEM image of elemental antimony prepared in Example 1.

[0038] Figure 3 This is a reaction route diagram for the ionic liquid prepared in Example 1. Detailed Implementation

[0039] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0040] Example 1:

[0041] A method for preparing a negative electrode active material: 0.01 mol of dihydro(2-chloroethyl) phosphate was mixed with 0.01 mol of N-methylimidazole and reacted at room temperature for 48 h. The product was collected, washed and purified with ethyl acetate, and then dried under vacuum for 24 h to obtain the ionic liquid, with a yield of 82.6%. The synthetic route is shown below. Figure 3 Dissolve 0.01 mol of antimony glycol in 100 mL of ethylene glycol, then add 1 g of the above ionic liquid as a complexing agent, stir until dissolved, and immerse a 0.1 mm × 100 mm × 100 mm zinc foil with a purity of 99.9% in 0.1 mol / L dilute hydrochloric acid for 60 s to activate it. After removal, rinse quickly three times with deionized water, air dry, and immediately immerse in the above solution. Stir and react at room temperature (25 °C) for 2 h, and the zinc foil surface gradually forms a deposition layer. After the reaction is complete, remove the zinc foil, scrape off the deposition layer with a scraper, collect the powder, wash twice with 0.1 mol / L dilute hydrochloric acid to dissolve and remove any possible trace zinc impurities, then wash repeatedly with a large amount of ethanol and deionized water until the washing solution is neutral, and finally dry in a vacuum drying oven at 60 °C for 12 h to obtain elemental antimony. SEM image ( Figure 1 ) and TEM image ( Figure 2 The results show that the product consists of particles with a diameter of approximately 400-500 nm, and its interior exhibits interconnected nanopores.

[0042] 2g of carbon nanotubes were placed in a fluidized bed reactor and heated to 800℃ under an argon atmosphere. Then, a mixture of argon and SO2 was introduced at a flow rate of 200mL / min, wherein the mass percentage of SO2 was 20%. The reaction was maintained at this atmosphere for 30min and then returned to room temperature to obtain sulfur-doped carbon nanotubes.

[0043] The elemental antimony and sulfur-doped carbon nanotubes obtained above were mixed in a mass ratio of 1:1 and placed in a ball mill jar. Anhydrous ethanol was used as the ball milling medium, and the mixture was ball milled for 5 hours under argon protection at a ball mill speed of 250 r / min. Then, the mixture was dried in a vacuum drying oven at 60℃ for 12 hours. Finally, it was heat-treated at 400℃ for 1 hour under argon protection and then allowed to return to room temperature to obtain the negative electrode active material.

[0044] Example 2: This example is basically the same as Example 1, except that the mass ratio of elemental antimony to sulfur-doped carbon nanotubes is 1:2.

[0045] Example 3: This example is basically the same as Example 1, except that the mass ratio of elemental antimony to sulfur-doped carbon nanotubes is 1:3.

[0046] Example 4: This example is basically the same as Example 1, except that the mass ratio of elemental antimony to sulfur-doped carbon nanotubes is 1:4.

[0047] Example 5: This example is basically the same as Example 1, except that the mass ratio of elemental antimony to sulfur-doped carbon nanotubes is 2:1.

[0048] Example 6: This example is basically the same as Example 1, except that the mass ratio of elemental antimony to sulfur-doped carbon nanotubes is 3:1.

[0049] Example 7: This example is basically the same as Example 1, except that the mass ratio of elemental antimony to sulfur-doped carbon nanotubes is 4:1.

[0050] Example 8: This example is basically the same as Example 1, except that antimony trichloride is used instead of antimony glycol in the same amount.

[0051] Comparative Example 1: This comparative example is basically the same as Example 1, except that no ionic liquid is added.

[0052] Comparative Example 2: This comparative example is basically the same as Example 1, except that the same mass of 1-ethyl-3-methylimidazolium chloride is used instead of the self-made ionic liquid as a complexing agent.

[0053] Comparative Example 3: This comparative example is basically the same as Example 1, except that multi-walled carbon nanotubes are added directly, that is, without sulfur doping treatment.

[0054] Comparative Example 4: This comparative example is basically the same as Example 1, except that it does not undergo heat treatment at 400°C.

[0055] Comparative Example 5: This comparative example is basically the same as Example 1, except that commercially available elemental antimony powder (300 mesh, JESK) of the same mass is used instead of the self-made elemental antimony.

[0056] Performance testing: The negative electrode active materials prepared in Examples 1-8 and Comparative Examples 1-5 of this invention were used as samples for performance testing.

[0057] The working electrode consists of a sample in a mass ratio of 8:1:1, conductive carbon black Super P, and a binder of polyacrylic acid. The electrode loading is 0.9-1.0 mg / cm³. 2 The slurry was mixed thoroughly and coated onto copper foil, then dried in a vacuum oven at 100℃ for 6 hours. Sodium metal was used as the counter electrode, a glass fiber diaphragm was used, and the electrolyte was a 1 mol / L NaClO4 solution of ethylene carbonate / diethyl carbonate (volume ratio 1:1), with 5% fluoroethylene carbonate added by volume. After standing for 24 hours, constant current charge-discharge tests were performed in the range of 0.01-3.00V. The electrode material was first activated by cycling at 50 mA / g for 10 cycles, followed by 500 cycles at 800 mA / g.

[0058] The test results are shown in Table 1 below; Table 1:

[0059] As shown in Table 1 above, the negative electrode active material prepared by this invention has excellent electrochemical performance.

[0060] A comparison of Examples 1-7 shows that, although the initial discharge specific capacity decreases with increasing sulfur-doped carbon nanotube content, the buffer network becomes more complete, and the capacity retention rate increases, indicating that volume expansion is effectively suppressed. However, with increasing elemental antimony content, although the capacity increases, the capacity retention rate decreases due to insufficient buffering.

[0061] A comparison between Example 1 and Example 8 shows that the capacity and retention rate of Example 8 are slightly lower than those of Example 1, possibly because the uniformity of the porous structure of elemental antimony formed by the coordination of antimony trichloride and ionic liquid is slightly inferior.

[0062] A comparison between Example 1 and Comparative Example 1 shows that when elemental antimony is deposited without ionized liquid, a porous structure cannot be formed. Not only is the initial capacity low, but it also pulverizes rapidly during cycling, resulting in poor capacity retention.

[0063] A comparison between Example 1 and Comparative Example 2 shows that the capacity and retention rate of Comparative Example 2 are slightly lower than those of Example 1. This may be due to the lack of specific coordination of phosphate ester groups, which prevents the formation of an effective porous structure. This highlights the crucial role of the self-made ionic liquid.

[0064] The comparison between Example 1 and Comparative Example 3 shows that sulfur doping is crucial for maintaining interface stability.

[0065] A comparison between Example 1 and Comparative Example 4 shows that the lack of heat treatment results in a weaker interface between elemental antimony and sulfur-doped carbon nanotubes, which are easily detached during cycling, thus reducing the capacity retention rate.

[0066] A comparison between Example 1 and Comparative Example 5 shows that, due to the possible lack of an internally interconnected nanoporous buffer structure, even when combined with sulfur-doped carbon nanotubes, it is difficult to withstand repeated volume expansion, thus resulting in the lowest capacity retention rate.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing elemental antimony, characterized in that, include: Prepare an antimony salt solution containing a complexing agent; An active metal substrate is immersed in an antimony salt solution to carry out a displacement reaction, wherein the standard electrode potential of the active metal is lower than that of Sb. 3+ / Sb standard electrode potential; Remove the active metal substrate, scrape off the surface product, wash it with hydrochloric acid and then with deionized water, and finally vacuum dry it.

2. The method for preparing elemental antimony as described in claim 1, characterized in that, The complexing agent is a phosphonic imidazole ionic liquid.

3. The method for preparing elemental antimony as described in claim 1, characterized in that, The cationic structural formula of the phosphonic acid imidazole ionic liquid is as follows: Where L represents alkylene and R represents alkyl.

4. The method for preparing elemental antimony as described in claim 1, characterized in that, The active metal substrate is selected from at least one of zinc, iron, aluminum, magnesium, and manganese, or from an alloy containing the above metals as the main components.

5. The method for preparing elemental antimony as described in claim 1, characterized in that, The active metal substrate is in the form of foil, sheet, plate, or film.

6. The method for preparing elemental antimony as described in claim 1, characterized in that, The active metal substrate is pre-activated with hydrochloric acid.

7. A type of elemental antimony, characterized in that, The elemental antimony prepared by any one of claims 1-6 has a nanoporous structure.

8. The application of elemental antimony as described in claim 7 in the negative electrode active material of sodium-ion batteries.

9. The application as described in claim 8, characterized in that, The sodium-ion battery negative electrode active material also includes carbon nanotubes.

10. The application as described in claim 9, characterized in that, The carbon nanotubes are treated with sulfur doping.

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