A composite material based on a multidimensional alloy compound and its preparation method, and its application in sodium storage.

Abstract

This invention discloses a composite material based on a multidimensional alloy compound, its preparation method, and its application in sodium storage, relating to the field of sodium-ion battery anode materials technology. The chemical formula of the composite material is MNPQ-C@MNPQX-C@C@Na4Ti5O 12 -C includes a core layer formed by high-entropy alloys and carbon composites, an intermediate layer formed by multidimensional sulfide heterostructures and carbon composites, a carbon layer, and the zero-strain material Na4Ti5O. 12 The shell formed by the composite material with carbon is used to prepare the anode material for sodium-ion batteries, exhibiting excellent rate performance and cycle stability. This invention, through the aforementioned composite material, progressively improves the structural stability of the material from the inside out, enabling uniform diffusion of internal stress and enhancing the material's high-rate cycle stability. This, in turn, solves the problems of poor structural stability and unfavorable reaction kinetics in alloy materials during the reaction process.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery anode material technology, specifically to a composite material based on a multidimensional alloy compound, its preparation method, and its sodium storage application. Background Technology

[0002] Driven by the global energy transition and carbon neutrality goals, sodium-ion batteries have become a focal point of next-generation energy storage technology due to their abundant resources, low cost, and environmental friendliness. Compared to traditional lithium-ion batteries, although sodium-ion batteries exhibit significant advantages in safety, sustainability, and economy, the large radius of sodium ions makes their electrode materials prone to cracking and pulverization during insertion / extraction, leading to battery capacity degradation. Therefore, to meet the ever-increasing demand for energy density, it is urgent to develop electrode materials that combine high energy density and excellent structural stability.

[0003] Alloy materials, with their unique electronic structure and multi-electron reaction mechanism, are considered promising anode materials for sodium-ion batteries due to their abundant resources and high theoretical capacity. However, alloy anode materials experience drastic volume changes and slow ion diffusion rates during the reaction process, leading to severe electrochemical degradation.

[0004] Therefore, effectively mitigating the volume effect of alloy anodes and accelerating ion transport has become a key scientific issue in improving the stability of sodium electrochemical cycling. To address this challenge, it is urgent to develop material design strategies with synergistic mechano-electrochemical effects to solve the problems of poor structural stability and unfavorable reaction kinetics in alloy materials during the reaction process. Summary of the Invention

[0005] The purpose of this invention is to provide a composite material based on a multidimensional alloy compound, its preparation method, and its application in sodium storage. The composite material includes an inner layer with high entropy, supplemented by a carbon network to stabilize the structure and improve conductivity; a middle layer is a multidimensional sulfide heterostructure; and an outermost layer is a zero-strain material shell. Through this design, the structural stability of the material is gradually improved from the inside out, resulting in uniform diffusion of internal stress and enhanced high-rate cycling stability. This addresses the problems of poor structural stability and unfavorable reaction kinetics in alloy materials during reactions.

[0006] Based on the above objectives, this invention discloses a composite material with a multi-layered core-shell structure, comprising, from the inside out: The core layer is a composite material of high-entropy alloy and carbon. The high-entropy alloy is composed of metallic elements M, N, P and Q, where M, N and P are each independently selected from one of Sb, Sn, Ge and Bi, and M, N and P are different metallic elements; Q is selected from one or more of Cr, Mn, Ni, Co and Fe. The intermediate layer is a composite material of multidimensional sulfide heterostructure and carbon. The metal elements in the multidimensional sulfide heterostructure are the same as the metal elements in the high-entropy alloy of the core layer. Its chemical formula is MNPQX, where X is at least two anionic elements selected from S, Se and O. The carbon layer, which is a continuous carbon layer or carbon network, is located outside the intermediate layer; The shell is made of zero-strain material Na4Ti5O 12 Composite materials with carbon; The chemical formula of the composite material is MNPQ-C@MNPQX-C@C@Na4Ti5O 12 -C.

[0007] This invention also provides a method for preparing the above-mentioned multidimensional alloy-type compound composite material, comprising the following steps: S1: Dissolve the organic ligand in organic solvent C to form solution A. Then dissolve the M source, N source, P source and Q source in organic solvent D and add a small amount of dilute hydrochloric acid to assist in dissolution to form solution B. Mix solution A and solution B and react in a closed environment. After separation and washing, the high-entropy multimetal-organic framework precursor is obtained. S2: The high-entropy multimetal-organic framework precursor obtained in step S1 is mixed with the X source and then calcined at high temperature under an inert atmosphere while simultaneously introducing a low molecular weight gas containing C to obtain the MNPQ-C@MNPQX-C@C composite material. S3: Sodium source and titanium source are thoroughly mixed and calcined at high temperature in an oxygen-containing atmosphere to obtain Na2Ti3O7; then Na2Ti3O7 and carbon source are thoroughly mixed in the liquid phase, and the powder obtained after separation is calcined in an inert atmosphere for pyrolysis to obtain Na2Ti3O7-C material. S4: The MNPQ-C@MNPQX-C@C composite material obtained in S2 and the Na2Ti3O7-C material obtained in S3 are thoroughly mechanically mixed, and then sintered under an inert atmosphere to obtain MNPQ-C@MNPQX-C@C@Na4Ti5O 12 -C; The inert atmosphere is one or more of nitrogen-hydrogen, argon-hydrogen, nitrogen, and argon.

[0008] Preferably, in S1, the organic ligand is one or more of 2-methylimidazole, 1,2-cyclohexanediamine, terephthalic acid, and trimesic acid; Organic solvent C is one or more of ethanol, ethylene glycol, and N,N-dimethylformamide, and the concentration of organic ligand in solution A is 0.1-35 mol / L; The M source, N source, P source, and Q source are each independently selected from one or more of the corresponding metal nitrates and / or chlorides; and the total concentration of the salt corresponding to each metal element is 0.03-1.5 mol / L; the concentration of the dilute hydrochloric acid used for dissolution is 1-2 mol / L, and the volume is 0.5-2 mL.

[0009] The reaction temperature is 120-300℃ and the time is 6-30h.

[0010] Preferably, the organic solvent D in S1 is one or more of ethanol, diethyl ether, and acetone.

[0011] Preferably, the molar ratio of each metal element in the M source, N source, P source and Q source of S1 is (0.3-2):(0.3-2):(0.3-2):(0.05-0.15); The ratio of the sum of the molar amounts of metal elements in the organic ligand and the M, N, P, and Q sources is (2-6):1.

[0012] Preferably, in S2, the X source is two or more of selenium powder, sulfur powder, or oxygen, and the low molecular weight gas containing C is one or more of methane, ethane, and formaldehyde.

[0013] Preferably, in step S2, X is sulfur and selenium, and the molar ratio of sulfur to selenium is (2-5):1. The mass ratio of the high-entropy multimetal-organic framework precursor to the sum of the masses of sulfur and selenium in the X source is 1:(0.2-0.5). The flow rate of low molecular weight gases containing carbon is 50-1000 mL / min; The MNPQ-C@MNPQX-C@C composite material was prepared by mixing the X source with a high-entropy multimetal-organic framework precursor and then calcining it at 500-900℃ for 0.5-24h under an inert atmosphere.

[0014] Preferably, in S2, X is two or more of sulfur, selenium, and oxygen, and includes the element oxygen. The molar ratio of sulfur, selenium, or the sum of sulfur and selenium to oxygen is 1:9-4:1; the mass ratio of the high-entropy polymetallic organic framework precursor to sulfur and / or selenium in the X source is 1:0.2-0.5. The flow rate of the low molecular weight gas containing carbon is 50-1000 mL / min; the preparation of the MNPQ-C@MNPQX-C@C composite material adopts the method of first mixing the X source with the high entropy polymetallic organic framework precursor and calcining it at a high temperature of 500-900℃ for 0.5-24h in an inert atmosphere, and then placing the calcined product in air for secondary calcination, wherein the air flow rate is 50-500 mL / min, the secondary calcination temperature is 300-400℃, and the treatment time is 1min-1h.

[0015] Preferably, in S3, the sodium source is one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate; the titanium source is one or more of tetrabutyl titanate, titanium dioxide, and titanium tetraisopropoxide; and the carbon source is one or more of glucose, fructose, and starch. In the titanium source and the sodium source, the molar ratio of titanium to sodium is (2.01-2.1):3; The high-temperature calcination temperature is 500-900℃, and the time is 1-2 hours; In the carbon source and Na2Ti3O7, the molar ratio of carbon to titanium is (0.01-0.1):1; the mixing method is to disperse Na2Ti3O7 in deionized water or ethanol and then add the carbon source. After thorough dispersion, the mixture is stirred at 60-80℃ until dry; the pyrolysis conditions are an inert atmosphere, a temperature of 450-550℃, and a time of 0.5-2h.

[0016] Preferably, in S4, the sintering temperature is 400-500℃ and the sintering time is 0.1-1h.

[0017] The multidimensional alloy composite material provided by this invention is used in energy storage batteries.

[0018] Therefore, the present invention, employing the above-mentioned composite material based on a multidimensional alloy compound, its preparation method, and its sodium storage application, possesses the following beneficial effects: (1) The composite material of the present invention uses a carbon-containing high-entropy alloy core (MNPQ-C) as an active inner layer. Its high configurational entropy effect significantly suppresses lattice distortion and phase separation, improves the structural thermal stability and phase transformation fatigue resistance of the material during repeated sodium ion insertion / extraction, and effectively delays pulverization and failure during cycling. In addition, Q metal, as a non-alloying reactive metal, can provide a scaffold effect, further improving the structural stability of the material.

[0019] (2) The intermediate layer is a double anion co-modified layer with the following characteristics: 1) Metal oxo compounds (oxides, sulfides, selenides) have a smaller volume effect than metal alloys, and the presence of anionic chemical bonds (S–Se, SO, Se-O) can further stabilize the crystal structure through strong covalent bonding; 2) Double anion modification can form Schottky heterojunctions at the interface, thereby improving the ionic conductivity of the material; 3) Metal oxo compounds also have a high theoretical capacity and will not cause capacity decay after the alloy material is combined with the material. Therefore, the synergistic introduction of anions not only suppresses the volume fluctuation of the alloy material during charging and discharging, but also improves the reaction kinetics of the material, achieving synergistic enhancement of conductivity and structural stability, and significantly reducing the overall volume expansion rate of the material at high rates while maintaining high specific capacity, thus achieving a triple balance of "capacity-conductivity-strain".

[0020] (3) Zero-strain interface layer in this invention: Na4Ti5O 12 Na₄Ti₅O in –C 12 It possesses a spinel structure, exhibits near-zero volume strain during sodium ion insertion, and is itself a fast ion conductor for sodium ions. Therefore, sodium-ion battery anode materials made using this composite exhibit excellent rate performance and cycle stability.

[0021] (4) Carbon materials are included in the entire material design. This material not only forms an effective carbon conductive network to improve the electronic conductivity of the material, but also has a good slow-release effect, thereby suppressing the material framework morphology cracking caused by stress concentration, thereby further improving the conductivity and structural stability of the material.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 The image shows a SEM image of the multidimensional alloy composite material prepared in Example 1. Figure 2 The elemental distribution diagram of the multidimensional alloy composite material prepared in Example 1 is shown below. Figure 3 The image shows an HRTEM image of the multidimensional alloy composite material prepared in Example 1. Figure 4 The graph shows the cyclic performance of the multidimensional alloy composite material prepared in Example 1. Detailed Implementation

[0024] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0025] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0026] The present invention will be further described below with reference to the embodiments and accompanying drawings. All chemicals and reagents used in the embodiments were purchased from the market.

[0027] Example 1 This embodiment provides a multidimensional alloy composite material, the preparation method of which is as follows: (1) Weigh 7.6356 g of 2-methylimidazole and dissolve it in 20 mL of ethylene glycol to form solution A. Weigh 2.6052 g of tin tetrachloride, 2.2812 g of antimony trichloride, 3.1534 g of bismuth trichloride, and 0.1829 g of anhydrous cobalt nitrate and dissolve them in 20 mL of ethanol. Add 1 mL of 1.5 mol / L dilute hydrochloric acid to form solution B. After complete dissolution, slowly add solution A to solution B under continuous stirring. After the addition is complete, transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in a constant temperature oven at 180 °C for 18 h. After the reaction is complete, filter, wash, and dry to obtain the high-entropy multimetal-organic framework precursor SnSbBiCo. 0.1 -C.

[0028] (2) Weigh SnSbBiCo 0.1 1.0 g of -C precursor, 0.1857 g of sulfur powder, and 0.1143 g of selenium powder were placed in an agate mortar, with a small amount of anhydrous ethanol added as a grinding aid. The mixture was continuously ground until homogeneous. The powder mixture was transferred to a porcelain boat and then placed in a tube furnace. Under an argon-hydrogen atmosphere, the mixture was heated to 750°C at a heating rate of 5°C / min, while methane gas was introduced at a flow rate of 300 mL / min. The mixture was calcined under these conditions for 6 h to obtain black carbon-coated SnSbBiCo. 0.1 -C@(SnSbBiCo 0.1 (SeS4)2-C@C composite material.

[0029] (3) Weigh 4.7695 g of sodium carbonate and 4.9117 g of titanium dioxide, mix them, and grind them in an agate mortar until uniform. Transfer the mixed powder to a porcelain boat, place it in a tube furnace, and calcine it at 5 °C / min to 800 °C under an air atmosphere for 1.5 h to obtain Na2Ti3O7 powder. Weigh 6.1823 g of Na2Ti3O7 and 0.0923 g of glucose, add 50 mL of deionized water, and stir until the carbon source is fully dispersed on the surface of the sodium titanate precursor. Transfer the mixed suspension to an evaporating dish, stir and evaporate it to dryness in a 70 °C water bath to obtain a dry powder. Place the powder in a porcelain boat, heat it at 5 °C / min to 500 °C under an argon-hydrogen atmosphere, and hold it for 1.5 h to obtain the Na2Ti3O7-C composite material.

[0030] (4) The SnSbBiCo obtained in step S2 0.1 -C@(SnSbBiCo 0.1 The (SeS4)-C@C composite material and the Na2Ti3O7-C material obtained in step S3 were mixed and ground in an agate mortar until homogeneous. The mixed powder was transferred to a porcelain boat and placed in a tube furnace. Under an argon-hydrogen atmosphere, the temperature was increased to 450℃ at 5℃ / min and held for 0.5h to obtain the final product, the multidimensional alloy composite material SnSbBiCo0.1-C@(SnSbBiCo0.1)(SeS4)2-C@C@Na4Ti5O 12 -C, the SEM image of this material is as follows Figure 1 As shown, this indicates the successful preparation of the multilayer material. The elemental distribution diagram of this material is as follows: Figure 2 As shown, the presence of elements such as Sn, Sb, Bi, Co, C, S, Se, Na, and Ti in the material confirms its successful preparation. Furthermore, the atomic ratio of Se to S was measured to be 1:4. The HRTEM image of this material is shown below. Figure 3 As shown, the corresponding steps on the surface will synthesize the corresponding layers, which effectively proves the successful preparation of this multilayer composite material.

[0031] Comparative Example 1 This comparative example is basically the same as Example 1, except that it does not contain Co. The specific preparation method is as follows: (1) Weigh 7.3893 g of 2-methylimidazole and dissolve it in 20 mL of ethylene glycol to form solution A. Weigh 2.6052 g of tin tetrachloride, 2.2812 g of antimony trichloride, and 3.1534 g of bismuth trichloride and dissolve them in 20 mL of ethanol. Add 1 mL of 1.5 mol / L dilute hydrochloric acid to form solution B. After complete dissolution, slowly add solution A to solution B under continuous stirring. After the addition is complete, transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in a constant temperature oven. React at 180 °C for 18 h. After the reaction is complete, filter, wash, and dry to obtain the high-entropy multimetal-organic framework precursor SnSbBi-C.

[0032] (2) Weigh 1.0 g of SnSbBi-C precursor, 0.1857 g of sulfur powder, and 0.1143 g of selenium powder, place them in an agate mortar, add a small amount of anhydrous ethanol as a grinding aid, and continuously grind to make the two uniformly mixed. Transfer the mixed powder to a porcelain boat, and then place it in a tube furnace. Heat it to 750℃ at a heating rate of 5℃ / min under an argon-hydrogen atmosphere, while simultaneously introducing methane gas at a flow rate of 300 mL / min. Calcinate under these conditions for 6 h to obtain black carbon-coated SnSbBi-C@(SnSbBi)(SeS4)2-C@C composite material.

[0033] (3) Weigh 4.7695 g of sodium carbonate and 4.9117 g of titanium dioxide, mix them, and grind them in an agate mortar until uniform. Transfer the mixed powder to a porcelain boat, place it in a tube furnace, and calcine it at 5 °C / min to 800 °C under an air atmosphere for 1.5 h to obtain Na2Ti3O7 powder. Weigh 6.1823 g of Na2Ti3O7 and 0.0923 g of glucose, add 50 mL of deionized water, and stir until the carbon source is fully dispersed on the surface of the sodium titanate precursor. Transfer the mixed suspension to an evaporating dish, stir and evaporate it to dryness in a 70 °C water bath to obtain a dry powder. Place the powder in a porcelain boat, heat it at 5 °C / min to 500 °C under an argon-hydrogen atmosphere, and hold it for 1.5 h to obtain the Na2Ti3O7-C composite material.

[0034] (4) The SnSbBi-C@(SnSbBi)(SeS4)-C@C composite material obtained in step S2 and the Na2Ti3O7-C material obtained in step S3 were mixed and ground in an agate mortar until homogeneous. The mixed powder was transferred to a porcelain boat and placed in a tube furnace. Under an argon-hydrogen atmosphere, the temperature was increased to 450℃ at 5℃ / min and held for 0.5h to obtain the final product, the multidimensional alloy composite material SnSbBi-C@(SnSbBi)(SeS4)2-C@C@Na4Ti5O 12 -C.

[0035] Comparative Example 2 The process is basically the same as in Example 1, except that in step (2), (SnSbBiCo) is not present. 0.1 The preparation method of the (SeS4)-C@C intermediate layer is as follows: (1) Weigh 7.6356 g of 2-methylimidazole and dissolve it in 20 mL of ethylene glycol to form solution A. Weigh 2.6052 g of tin tetrachloride, 2.2812 g of antimony trichloride, 3.1534 g of bismuth trichloride, and 0.1829 g of anhydrous cobalt nitrate and dissolve them in 20 mL of ethanol. Add 1 mL of 1.5 mol / L dilute hydrochloric acid to form solution B. After complete dissolution, slowly add solution A to solution B under continuous stirring. After the addition is complete, transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in a constant temperature oven at 180 °C for 18 h. After the reaction is complete, filter, wash, and dry to obtain the high-entropy multimetal-organic framework precursor SnSbBiCo. 0.1 -C.

[0036] (2) Weigh 4.7695 g of sodium carbonate and 4.9117 g of titanium dioxide, mix them, and grind them in an agate mortar until uniform. Transfer the mixed powder to a porcelain boat, place it in a tube furnace, and calcine it at 5 °C / min to 800 °C under an air atmosphere for 1.5 h to obtain Na2Ti3O7 powder. Weigh 6.1823 g of Na2Ti3O7 and 0.0923 g of glucose, add 50 mL of deionized water, and stir until the carbon source is fully dispersed on the surface of the sodium titanate precursor. Transfer the mixed suspension to an evaporating dish, stir and evaporate it to dryness in a 70 °C water bath to obtain a dry powder. Place the powder in a porcelain boat, heat it at 5 °C / min to 500 °C under an argon-hydrogen atmosphere, and hold it for 1.5 h to obtain the Na2Ti3O7-C composite material.

[0037] (3) The SnSbBiCo obtained in step (1) 0.1The -C composite material and the Na2Ti3O7-C material obtained in step (2) were mixed and ground in an agate mortar until homogeneous. The mixed powder was transferred to a porcelain boat, placed in a tube furnace, and heated to 450℃ at 5℃ / min under an argon-hydrogen atmosphere. After holding at this temperature for 0.5h, the final product, the multidimensional alloy composite material SnSbBiCo, was obtained. 0.1 -C@Na4Ti5O 12 -C.

[0038] Comparative Example 3 The process is basically the same as in Example 1, except that in step (2), the outermost layer of Na4Ti5O is not included. 12 -C, the specific preparation method is as follows: (1) Weigh 7.6356 g of 2-methylimidazole and dissolve it in 20 mL of ethylene glycol to form solution A. Weigh 2.6052 g of tin tetrachloride, 2.2812 g of antimony trichloride, 3.1534 g of bismuth trichloride, and 0.1829 g of anhydrous cobalt nitrate and dissolve them in 20 mL of ethanol. Add 1 mL of 1.5 mol / L dilute hydrochloric acid to form solution B. After complete dissolution, slowly add solution A to solution B under continuous stirring. After the addition is complete, transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in a constant temperature oven at 180 °C for 18 h. After the reaction is complete, filter, wash, and dry to obtain the high-entropy multimetal-organic framework precursor SnSbBiCo. 0.1 -C.

[0039] (2) Weigh SnSbBiCo 0.1 1.0 g of -C precursor, 0.1857 g of sulfur powder, and 0.1143 g of selenium powder were placed in an agate mortar, with a small amount of anhydrous ethanol added as a grinding aid. The mixture was continuously ground until homogeneous. The powder mixture was transferred to a porcelain boat and then placed in a tube furnace. Under an argon-hydrogen atmosphere, the mixture was heated to 750°C at a heating rate of 5°C / min, while methane gas was introduced at a flow rate of 300 mL / min. The mixture was calcined under these conditions for 6 h to obtain black carbon-coated SnSbBiCo0.1-C@(SnSbBiCo). 0.1 (SeS4)2-C@C composite material.

[0040] Example 2 (1) Weigh 6.0099 g of 2-methylimidazole and dissolve it in 20 mL of ethylene glycol to form solution A. Weigh 3.1263 g of tin tetrachloride, 2.7374 g of antimony trichloride, 3.7841 g of bismuth trichloride, and 0.1098 g of anhydrous cobalt nitrate and dissolve them in 20 mL of ethanol. Add 1 mL of 1.5 mol / L dilute hydrochloric acid to form solution B. After complete dissolution, slowly add solution A to solution B under continuous stirring. After the addition is complete, transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in a constant temperature oven at 120 °C for 6 h. After the reaction is complete, filter, wash, and dry to obtain the high-entropy multimetal-organic framework precursor SnSbBiCo. 0.05 -C.

[0041] (2) Weigh SnSbBiCo 0.05 1.0 g of -C precursor, 0.0896 g of sulfur powder, and 0.1104 g of selenium powder were placed in an agate mortar, with a small amount of anhydrous ethanol added as a grinding aid. The mixture was continuously ground until homogeneous. The powder mixture was transferred to a porcelain boat and then placed in a tube furnace. Under an argon-hydrogen atmosphere, the mixture was heated to 500°C at a heating rate of 5°C / min, while methane gas was introduced at a flow rate of 50 mL / min. The mixture was calcined under these conditions for 0.5 h to obtain black carbon-coated SnSbBiCo. 0.05 -C@(SnSbBiCo 0.05 (SeS2)2-C@C composite material.

[0042] (3) Weigh 4.7695g of sodium carbonate and 4.8159g of titanium dioxide, mix them, and grind them in an agate mortar until uniform. Transfer the mixed powder to a porcelain boat, place it in a tube furnace, and calcine it at 500℃ / min in air atmosphere for 1 h to obtain Na2Ti3O7 powder. Weigh 6.0617g of Na2Ti3O7 and 0.0181g of glucose, add 50 mL of deionized water, and stir until the carbon source is fully dispersed on the surface of the sodium titanate precursor. Transfer the mixed suspension to an evaporating dish, stir and evaporate it to dryness in a 60℃ water bath to obtain dry powder. Place the powder in a porcelain boat, heat it at 5℃ / min to 450℃ in argon-hydrogen atmosphere, and hold it for 0.5 h to obtain Na2Ti3O7-C composite material.

[0043] (4) The SnSbBiCo obtained in step S2 0.05 -C@(SnSbBiCo 0.05The (SeS2)-C@C composite material and the Na2Ti3O7-C material obtained in step S3 were mixed and ground into a uniform powder in an agate mortar. The mixed powder was transferred to a porcelain boat and placed in a tube furnace. Under an argon-hydrogen atmosphere, the temperature was increased to 400℃ at 5℃ / min and held for 0.1h to obtain the final product, the multidimensional alloy composite material SnSbBiCo. 0.05 -C@(SnSbBiCo 0.05 (SeS2)2-C@C@Na4Ti5O 12 -C.

[0044] Example 3 (1) Weigh 46.5525 g of 2-methylimidazole and dissolve it in 20 mL of ethylene glycol to form solution A. Weigh 7.8157 g of tin tetrachloride, 6.8436 g of antimony trichloride, 9.4602 g of bismuth trichloride, and 0.8232 g of anhydrous cobalt nitrate and dissolve them in 20 mL of ethanol. Add 1 mL of 1.5 mol / L dilute hydrochloric acid to form solution B. After complete dissolution, slowly add solution A to solution B under continuous stirring. After the addition is complete, transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in a constant temperature oven at 300 °C for 30 h. After the reaction is complete, filter, wash, and dry to obtain the high-entropy multimetal-organic framework precursor SnSbBiCo. 0.15 -C.

[0045] (2) Weigh ‌SnSbBiCo 0.15 1.0 g of -C precursor, 0.3351 g of sulfur powder, and 0.1649 g of selenium powder were placed in an agate mortar, with a small amount of anhydrous ethanol added as a grinding aid. The mixture was continuously ground until homogeneous. The powder mixture was transferred to a porcelain boat and then placed in a tube furnace. Under an argon-hydrogen atmosphere, the mixture was heated to 900°C at a heating rate of 5°C / min, while methane gas was introduced at a flow rate of 1000 mL / min. The mixture was calcined under these conditions for 24 h to obtain black carbon-coated SnSbBiCo. 0.15 -C@(SnSbBiCo 0.15 (SeS5)2-C@C composite material.

[0046] (3) Weigh 4.7695g of sodium carbonate and 5.0315g of titanium dioxide, mix them, and grind them in an agate mortar until uniform. Transfer the mixed powder to a porcelain boat, place it in a tube furnace, and calcine it at 5℃ / min to 900℃ in an air atmosphere for 2 hours to obtain Na2Ti3O7 powder. Weigh 6.3331g of Na2Ti3O7 and 0.1892g of glucose, add 50 mL of deionized water, and stir until the carbon source is fully dispersed on the surface of the sodium titanate precursor. Transfer the mixed suspension to an evaporating dish, stir and evaporate it to dryness in an 80℃ water bath to obtain a dry powder. Place the powder in a porcelain boat, heat it at 5℃ / min to 550℃ in an argon-hydrogen atmosphere, and hold it for 2 hours to obtain the Na2Ti3O7-C composite material.

[0047] (4) The SnSbBiCo obtained in step S2 0.15 -C@(SnSbBiCo 0.15 The (SeS5)-C@C composite material and the Na2Ti3O7-C material obtained in step S3 were mixed and ground into a uniform powder in an agate mortar. The mixed powder was transferred to a porcelain boat and placed in a tube furnace. Under an argon-hydrogen atmosphere, the temperature was increased to 500℃ at 5℃ / min and held for 1 hour to obtain the final product, the multidimensional alloy composite material SnSbBiCo. 0.15 -C@(SnSbBiCo 0.15 (SeS5)2-C@C@C@Na4Ti5O 12 -C.

[0048] Example 4 (1) Weigh 7.6356 g of 2-methylimidazole and dissolve it in 20 mL of ethylene glycol to form solution A. Weigh 2.6052 g of tin tetrachloride, 2.2812 g of antimony trichloride, 3.1534 g of bismuth trichloride, and 0.1829 g of anhydrous cobalt nitrate and dissolve them in 20 mL of ethanol. Add 1 mL of 1.5 mol / L dilute hydrochloric acid to form solution B. After complete dissolution, slowly add solution A to solution B under continuous stirring. After the addition is complete, transfer the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor, seal it, and place it in a constant temperature oven at 180 °C for 18 h. After the reaction is complete, filter, wash, and dry to obtain the high-entropy multimetal-organic framework precursor SnSbBiCo. 0.1 -C.

[0049] (2) Weigh SnSbBiCo 0.11.0 g of -C precursor and 0.3 g of sulfur powder were placed in an agate mortar, with a small amount of anhydrous ethanol added as a grinding aid. The mixture was continuously ground until homogeneous. The powder mixture was transferred to a porcelain boat and then placed in a tube furnace. Under an argon-hydrogen atmosphere, the mixture was heated to 750°C at a heating rate of 5°C / min, while formaldehyde gas was introduced at a flow rate of 300 mL / min. The mixture was then calcined under these conditions for 6 h. The calcined product was then subjected to a second calcination in air at a flow rate of 100 mL / min, a second calcination temperature of 350°C, and a treatment time of 5 min. This yielded black carbon-coated SnSbBiCo. 0.1 -C@(SnSbBiCo 0.1 (SO)-C@C composite material. The specific ratio of S to O elements in this material was determined by an organic chemical elemental analyzer, as shown in Table 1, which shows the molar ratio of S and O elements in the sample.

[0050] (3) Weigh 4.7695 g of sodium carbonate and 4.9117 g of titanium dioxide, mix them, and grind them in an agate mortar until uniform. Transfer the mixed powder to a porcelain boat, place it in a tube furnace, and calcine it at 5 °C / min to 800 °C under an air atmosphere for 1.5 h to obtain Na2Ti3O7 powder. Weigh 6.1823 g of Na2Ti3O7 and 0.0923 g of glucose, add 50 mL of deionized water, and stir until the carbon source is fully dispersed on the surface of the sodium titanate precursor. Transfer the mixed suspension to an evaporating dish, stir and evaporate it to dryness in a 70 °C water bath to obtain a dry powder. Place the powder in a porcelain boat, heat it at 5 °C / min to 500 °C under an argon-hydrogen atmosphere, and hold it for 1.5 h to obtain the Na2Ti3O7-C composite material.

[0051] (4) The SnSbBiCo obtained in step S2 0.1 -C@(SnSbBiCo 0.1 The (S2O)-C@C composite material and the Na2Ti3O7-C material obtained in step S3 were mixed and ground into a uniform powder in an agate mortar. The mixed powder was transferred to a porcelain boat and placed in a tube furnace. Under an argon-hydrogen atmosphere, the temperature was increased to 450℃ at 5℃ / min and held for 0.5h to obtain the final product, the multidimensional alloy composite material SnSbBiCo. 0.1 -C@(SnSbBiCo 0.1 (SO)-C@C@Na4Ti5O 12 -C.

[0052] Table 1: SnSbBiCo 0.1 -C@(SnSbBiCo 0.1Mass ratio of S and O elements in (SO)-C@C composite materials

[0053] The multidimensional alloy composite materials prepared in Examples 1-4 and Comparative Examples 1-3, along with commercial Sn metal, were assembled into sodium-ion batteries according to the following steps, and their sodium storage performance was tested: The prepared products, acetylene black (conductive agent), and PVDF (HSV900, binder) were weighed at a mass ratio of 7:2:1, thoroughly ground, and then an appropriate amount of NMP was added to disperse and mix until a viscous slurry was formed. The slurry was then uniformly coated onto copper foil, dried at 85°C, and cut into 12mm diameter discs. Assembly was performed in an argon-atmospheric glove box, using a sodium metal disc as the counter electrode, a 1M NaPF6 solution (solvent EC:DEC volume ratio 1:1) as the electrolyte, and glass fiber (GradeGF / F) as the separator, to form a CR2032 coin cell. Constant current charge-discharge tests were conducted at 25°C at a rate of 5A / g between 0.1-3.0V. The cycle performance of Example 1 after 500 cycles is as follows: Figure 4 As shown in Table 2, the cycle performance of all the batteries prepared above is shown in Table 2.

[0054] Table 2: Comparison of battery performance data between Examples 1-4 and conventional examples and comparative examples 1-3

[0055] In this table, the negative electrode material for the standard example is commercial Sn metal.

[0056] Data comparison revealed that Examples 1-4 all exhibited significant advantages in battery performance, as detailed below: Leading initial charge capacity: The initial charge capacity of all samples was above 620 mAh / g, while the initial charge capacity of the battery prepared by the material in Example 1 reached 654 mAh / g, which was the highest among all test groups. It was 108 mAh / g higher than the 546 mAh / g of the conventional example, and 55 mAh / g, 67 mAh / g, and 78 mAh / g higher than the 599 mAh / g, 587 mAh / g, and 576 mAh / g of Comparative Examples 1-3, respectively, demonstrating superior initial energy storage capacity.

[0057] The battery exhibits outstanding cycle stability: after 500 cycles, the capacity remains at or above 450 mAh / g. The battery with a specific charge capacity of 513 mAh / g prepared from the material in Example 1 is even higher than that of the conventional example (319 mAh / g) and the comparative examples 1-3 (422 mAh / g, 401 mAh / g, and 381 mAh / g), which are 194 mAh / g, 91 mAh / g, 112 mAh / g, and 132 mAh / g higher, respectively. This indicates that the battery has a slower capacity decay and a longer service life during long-term charge-discharge cycles.

[0058] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and does not limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite material based on a multidimensional alloying compound, characterized in that, The composite material has a multi-layered core-shell structure, consisting of, from the inside out: The core layer is a composite material of high-entropy alloy and carbon. The high-entropy alloy is composed of metallic elements M, N, P and Q, where M, N and P are each independently selected from one of Sb, Sn, Ge and Bi, and M, N and P are different metallic elements; Q is selected from one or more of Cr, Mn, Ni, Co and Fe. The intermediate layer is a composite material of multidimensional sulfide heterostructure and carbon. The metal elements in the multidimensional sulfide heterostructure are the same as the metal elements in the high-entropy alloy of the core layer. Its chemical formula is MNPQX, where X is at least two anionic elements selected from S, Se and O. The carbon layer, which is a continuous carbon layer or carbon network, is located outside the intermediate layer; The shell is made of zero-strain material Na4Ti5O 12 Composite materials with carbon; The chemical formula of the composite material is MNPQ-C@MNPQX-C@C@Na4Ti5O 12 -C.

2. A method for preparing a composite material based on a multidimensional alloy compound as described in claim 1, characterized in that, Includes the following steps: S1: Dissolve the organic ligand in organic solvent C to form solution A. Then dissolve the M source, N source, P source and Q source in organic solvent D and add a small amount of dilute hydrochloric acid to assist in dissolution to form solution B. Mix solution A and solution B and react in a closed environment. After separation and washing, the high-entropy multimetal-organic framework precursor is obtained. S2: The high-entropy multimetal-organic framework precursor obtained in step S1 is mixed with the X source and then calcined at high temperature under an inert atmosphere while simultaneously introducing a low molecular weight gas containing C to obtain the MNPQ-C@MNPQX-C@C composite material. S3: Sodium source and titanium source are thoroughly mixed and calcined at high temperature in an oxygen-containing atmosphere to obtain Na2Ti3O7; then Na2Ti3O7 and carbon source are thoroughly mixed in the liquid phase, and the powder obtained after separation is calcined in an inert atmosphere for pyrolysis to obtain Na2Ti3O7-C material. S4: The MNPQ-C@MNPQX-C@C composite material obtained in S2 and the Na2Ti3O7-C material obtained in S3 are thoroughly mechanically mixed, and then sintered under an inert atmosphere to obtain MNPQ-C@MNPQX-C@C@Na4Ti5O 12 -C; In S2, S3 and S4, the inert atmosphere is one or more of nitrogen-hydrogen, argon-hydrogen, nitrogen and argon.

3. The method for preparing a composite material based on a multidimensional alloy compound according to claim 2, characterized in that, In S1, the organic ligand is one or more of 2-methylimidazole, 1,2-cyclohexanediamine, terephthalic acid and trimesic acid; Organic solvent C is one or more of ethanol, ethylene glycol, and N,N-dimethylformamide, and the concentration of organic ligand in solution A is 0.1-35 mol / L; Organic solvent D is one or more of ethanol, diethyl ether, and acetone; source M, source N, source P, and source Q are each independently selected from one or more of the corresponding metal nitrates and / or chlorides; and the total concentration of the salt corresponding to each metal element is 0.03-1.5 mol / L; the concentration of the dilute hydrochloric acid used to assist dissolution is 1-2 mol / L, and the volume is 0.5-2 mL; The reaction temperature is 120-300℃ and the time is 6-30h.

4. The method for preparing a composite material based on a multidimensional alloy compound according to claim 2, characterized in that, In the M, N, P, and Q sources of S1, the molar ratio of each metal element is (0.3-2):(0.3-2):(0.3-2):(0.05-0.15); The ratio of the sum of the molar amounts of metal elements in the organic ligand and the M, N, P, and Q sources is (2-6):

1.

5. The method for preparing a composite material based on a multidimensional alloy compound according to claim 2, characterized in that, In S2, the X source is two or more of selenium powder, sulfur powder, or oxygen, and the low molecular weight gas containing C is one or more of methane, ethane, or formaldehyde.

6. The method for preparing a composite material based on a multidimensional alloy compound according to claim 5, characterized in that, In step S2, X represents sulfur and selenium, and the molar ratio of sulfur to selenium is (2-5):

1. The mass ratio of the high-entropy multimetal-organic framework precursor to the sum of the masses of sulfur and selenium in the X source is 1:(0.2-0.5). The flow rate of low molecular weight gases containing carbon is 50-1000 mL / min; The MNPQ-C@MNPQX-C@C composite material was prepared by mixing the X source with a high-entropy multimetal-organic framework precursor and then calcining it at 500-900℃ for 0.5-24h under an inert atmosphere.

7. The method for preparing a composite material based on a multidimensional alloy compound according to claim 5, characterized in that, In S2, X is two or more of sulfur, selenium, and oxygen, and contains the element oxygen. The ratio of the amount of sulfur, selenium, or the sum of sulfur and selenium to the amount of oxygen is 1:9-4:1; the mass ratio of the high-entropy polymetallic organic framework precursor to sulfur, selenium, or sulfur and selenium in the X source is 1:0.2-0.

5. The flow rate of the low molecular weight gas containing carbon is 50-1000 mL / min; the preparation of the MNPQ-C@MNPQX-C@C composite material adopts the method of first mixing the X source with the high entropy polymetallic organic framework precursor and calcining it at a high temperature of 500-900℃ for 0.5-24h in an inert atmosphere, and then placing the calcined product in air for secondary calcination, wherein the air flow rate is 50-500 mL / min, the secondary calcination temperature is 300-400℃, and the treatment time is 1min-1h.

8. The method for preparing a composite material based on a multidimensional alloy compound according to claim 2, characterized in that, In S3, the sodium source is one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate; the titanium source is one or more of tetrabutyl titanate, titanium dioxide, and titanium tetraisopropoxide; and the carbon source is one or more of glucose, fructose, and starch. In the titanium source and the sodium source, the molar ratio of titanium to sodium is (2.01-2.1):3; The high-temperature calcination temperature is 500-900℃, and the time is 1-2 hours; In the carbon source and Na2Ti3O7, the molar ratio of carbon to titanium is (0.01-0.1):1; the mixing method is to disperse Na2Ti3O7 in deionized water or ethanol and then add the carbon source. After thorough dispersion, the mixture is stirred at 60-80℃ until dry; the pyrolysis conditions are an inert atmosphere, a temperature of 450-550℃, and a time of 0.5-2h.

9. The method for preparing a composite material based on a multidimensional alloy compound according to claim 2, characterized in that, In S4, the sintering temperature is 400-500℃ and the time is 0.1-1h.

10. An application of the multidimensional alloy composite material as described in claim 1, characterized in that, The multidimensional alloy composite material is used in energy storage batteries.

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