CN116387481A - Preparation method and application of a heterogeneous structure yolk-shell type double transition metal selenide composite material - Google Patents

Abstract

The invention discloses a preparation method and application of a heterostructure yolk shell type double transition metal selenide composite material. The chemical formula of the composite material is TM ₁ Se ₂ @TM ₁ Se ₂ /TM ₂ Se ₂ Wherein, TM ₁ And TM ₂ Respectively representing two different transition metal elements. The composite material prepared by the invention has uniform particles, a yolk shell structure has large specific surface area, a thin shell and an internal gap enable electrolyte to fully permeate, buffer space can be provided for volume expansion, the structure is kept stable, and the composite material is prepared from TM ₁ Se ₂ And TM ₂ Se ₂ The bimetal synergistic effect generated by the heterostructure promotes sodium ion diffusion and improves the multiplying power performance of the battery. In addition, the invention relates to a simple preparation methodThe single-component composite material has wide application range, and the prepared composite material has excellent multiplying power performance and cycle performance.

Description

Preparation method of a heterogeneous structure egg yolk shell double transition metal selenide composite material Law and Application

technical field

The invention relates to the technical field of electrochemical energy materials, in particular to a method for preparing a yolk-shell double-transition metal selenide composite material with a heterogeneous structure and its application in negative electrode materials for sodium-ion batteries.

Background technique

With the increasing global demand for efficient and clean energy, the application prospects of wind energy, solar energy, tidal energy and other new energy sources are becoming more and more broad. With the rapid popularization of the power grid system and the introduction of portable new energy into daily life, energy storage equipment, as the most critical part of it, has attracted much attention. In the past few decades, lithium-ion batteries have been widely studied and applied, and the advantages of electrochemical energy storage technology have gradually emerged. However, the extremely large-scale promotion of lithium-ion batteries is restricted by the problem of limited lithium-ion resources, which makes the cost of batteries remain high. Sodium and lithium belong to the same main group of elements, with similar chemical properties, high abundance, environmental friendliness, and broad application prospects. However, due to the large radius of sodium ions, graphite anodes for lithium-ion batteries cannot be reversibly intercalated/deintercalated in the effective potential window when they are used as anode materials for sodium-ion batteries. Difficulty in inserting and embedding, poor conductivity and other problems.

In recent years, it has been found that transition metal selenides have the advantages of higher theoretical specific capacity, more stable structure, narrower energy band gap, etc., and the transition metal-selenium chemical bond is weaker than that in sulfide and oxide, It is very conducive to the rapid intercalation/deintercalation of sodium ions in the structure, so this material can be widely used in anode materials for sodium ion batteries. However, transition metal selenides have poor electronic conductivity and tend to cause large volume changes during the intercalation/extraction of sodium ions. Poor electronic conductivity leads to the fact that the actual specific capacity of transition metal selenides in the application process is much lower than the theoretical specific capacity, which is not conducive to the industrial production of high-capacity batteries; large volume changes will easily reduce the cycle stability of the battery, if applied in large-scale There may even be safety concerns in energy storage technology. The invention patent with the application number CN201910976902.1 uses a cobalt/iron bimetallic heterostructure to improve the conduction of electrons, but the carbon coating method used to improve the stability does not significantly inhibit the volume expansion, and the non-sodium ion storage The carbon layer of the cell tends to cause a decrease in specific capacity.

Contents of the invention

The invention provides a preparation method and application of a heterogeneous structure yolk-shell type double transition metal selenide sodium ion battery negative electrode material. The material has good electronic conduction, high sodium storage capacity, small volume change, large specific surface area and uniform particles. Has excellent rate and cycle performance. The heterogeneous structure egg yolk shell type double transition metal selenide sodium ion battery negative electrode material proposed by the present invention promotes the conduction of electrons through the synergistic effect of double transition metals. The large specific surface area increases the contact area between the electrode material and the electrolyte and promotes the reaction kinetics.

A method for preparing a yolk-shell type double-transition metal selenide composite material with a heterogeneous structure, comprising the following steps:

S1. Dissolving the organic ligand reagent and TM ₁ source in the reagent, and sequentially subjecting the solution to hydrothermal reaction, cooling, centrifugation, washing and drying, to obtain a transition metal-organic framework; wherein the TM ₁ source is Ti One or more of nitrate, phosphate, sulfate and chloride of Cr, Mn, Fe, Co, Ni, Cu or Zn;

S2. Uniformly disperse the transition metal-organic framework prepared in S1 in the reagent to obtain solution A; dissolve the _TM2 source and the precipitating agent in the reagent to obtain solution B; after mixing solution A and solution B, pass through heat preservation, cooling, centrifugation, washing and drying to obtain a transition metal-organic framework material coated with a double transition metal hydroxide of egg yolk shell structure; the TM _source is Ti, Cr, Mn, Fe, Co, Ni, One or more of nitrate, phosphate, sulfate and chloride of Cu or Zn;

S3. Under the protection of an inert gas, the transition metal-organic framework material coated with double transition metal hydroxide prepared in S2 is annealed and heat-treated with a certain proportion of selenium powder, and after cooling in the furnace, the composite material TM ₁ Se ₂ is obtained @TM ₁ Se ₂ /TM ₂ Se ₂ .

Further, the ratio of the amount of the _TM1 source to the organic ligand reagent in S1 is 1-5:5, the temperature of the hydrothermal reaction is 100-160°C, the time is 1-5h, and the drying temperature The condition is 60-100°C, and the time condition is 8-24h.

Further, the mass ratio of the precipitating agent, the transition metal-organic framework, and the TM _source in S2 is 1-5:0.24:1, the temperature condition of the heat preservation treatment is 60-90°C, and the time condition is 4 ～12h, the drying temperature condition is 60～100℃, and the time condition is 8～24h.

Further, in S3, the mass ratio of the double-transition metal hydroxide-coated transition metal-organic framework material to the selenium powder is 1:1-4;

Place the porcelain boat containing the transition metal-organic framework material coated with the double transition metal hydroxide and the selenium powder in a tube furnace, and first heat it to 200 °C in a hydrogen/argon or hydrogen/nitrogen mixed atmosphere. ~400°C, keep warm for 1~6h; then heat to 400~800°C under nitrogen or argon atmosphere, keep warm for 1~6h, the two-stage heating rate is 2~8°C/min.

Further, the organic ligand reagent is one or more of fumaric acid, benzoic acid, oxalic acid, and pyrazine;

The reagents in S1 and S2 are one or more of deionized water, methanol, ethanol, N,N-dimethylformamide, N,N-diethylformamide, acetonitrile, and acetone;

The precipitant includes one or more of ammonium chloride, urea, sodium hydroxide, and sodium carbonate.

The heterogeneous structure egg yolk shell type double transition metal selenide composite material prepared by the above preparation method.

Further, the composite material has a hollow egg yolk-eggshell structure with a particle size of 1-2 microns.

Application of the heterostructure yolk-shell type double-transition metal selenide composite material obtained by the above preparation method in the preparation of negative electrode active materials for sodium ion batteries.

A sodium ion battery, comprising an electrode sheet, a counter electrode, a diaphragm and an electrolyte, wherein the electrode sheet is made of the above-mentioned heterostructure egg yolk shell type double transition metal selenide composite material and acetylene black, polyvinylidene fluoride It is prepared by mixing at a mass ratio of 5-7:1-2:1, the counter electrode is a sodium metal sheet, the diaphragm is a glass fiber diaphragm, and the electrolyte is dissolved in 1mol·L ^- 1 sodium hexafluorophosphate Diethylene glycol methyl ether in the system.

A sodium ion battery, comprising an electrode sheet, a counter electrode, a diaphragm and an electrolyte, wherein the electrode sheet is made of the above-mentioned heterostructure egg yolk shell type double transition metal selenide composite material and acetylene black, polyvinylidene fluoride It is prepared by mixing at a mass ratio of 5-7:1-2:1, the counter electrode is a sodium vanadium phosphate positive electrode material, the diaphragm is a glass fiber diaphragm, and the electrolyte is composed of 1mol L ^-1 sodium hexafluorophosphate Soluble in diethylene glycol methyl ether in the system.

Compared with the prior art, the present invention includes the following beneficial effects:

(1) The yolk-shell double-transition metal selenide composite material with heterogeneous structure prepared by the present invention is a micron hollow egg yolk-eggshell structure particle, and its size is about 1-2 μm. The introduction of a tightly connected bimetallic heterojunction, which has a synergistic effect and multi-electron reaction, provides favorable conditions for reducing the hindrance of electron conduction and increasing the capacity of sodium; the innovatively designed hollow yolk shell structure not only increases the electrode material and The contact area of the electrolyte can reduce the volume change of the intercalation/de-sodium process without losing its tap density and volume specific capacity, increase the specific surface area, and improve the safety while improving the rate performance. The cycle performance of the negative electrode material is also improved.

(2) Using the composite material of the present invention as the negative electrode material of the sodium ion battery, charge and discharge tests are carried out under different current densities within a certain voltage range. Due to the synergistic effect of double-transition metals, which facilitate electron transfer and sodium ion diffusion kinetics, the eggshell layer of the double-transition metal heterostructure stabilizes the structure without losing its capacity, enabling the material to exhibit excellent rate and cycling It is a reliable anode material for realizing high capacity, high power and long life sodium ion battery.

(3) The present invention adopts the introduction of bimetallic synergistic effect to promote electron transfer, and designs the egg yolk shell structure of bimetallic selenide to provide a buffer space for volume change. The introduction of the bimetallic synergistic effect is through the use of selenides of two transition metal elements, which reduce the hindrance of charge transfer and promote electron transfer through abundant multi-electron reactions and unique built-in electric fields; There is a certain hollow area between the shell and the shell. This structure can not only alleviate the harm caused by the volume change to the cycle performance, but also do not lose its capacity because the shell also contains sodium ion storage sites. In addition, the large specific surface area enables The electrolyte fully contacts the negative electrode material, and the rate performance is improved.

(4) The preparation method of the present invention has mild preparation conditions. First, a transition metal-organic framework material is synthesized by a hydrothermal method, and then another transition metal source is introduced to react at a certain temperature to form a double transition metal hydroxide with a yolk-shell structure. The coated transition metal-organic framework material is finally selenized in a tube furnace to obtain the target material.

Description of drawings

Figures 1a-d are all SEM images of the heterostructured yolk-shell type cobalt diselenide/iron diselenide material prepared in Example 1 of the present invention.

Figures 2a-b are TEM images of the heterostructure yolk-shell type cobalt diselenide/iron diselenide material prepared in Example 1 of the present invention.

Fig. 3 is a graph of the rate performance of a battery assembled from heterogeneous yolk-shell type cobalt diselenide/iron diselenide materials prepared in Example 1 of the present invention.

Fig. 4 is a cycle performance diagram of batteries assembled from materials prepared in Example 1 and Comparative Example 1 of the present invention at a low current density of 0.2 Ag ⁻¹ .

Fig. 5 is a diagram of the cycle performance of a battery assembled from the heterostructured yolk-shell type cobalt diselenide/iron diselenide material prepared in Example 1 of the present invention at a high current density of 2Ag ^-1 .

Detailed ways

The technical solutions adopted in the present invention will be clearly and specifically described below through the examples and comparative examples. The examples and comparative examples are only examples of the present invention, do not represent all examples, and do not limit the scope of the present invention. . Embodiments in the present invention, as well as various changes or modifications made by those skilled in the art according to the present invention, these equivalent forms also belong to the protection scope of the present invention. Unless otherwise specified, the equipment and reagents used in the present invention are conventional commercially available products in the technical field.

<Example 1>

S1. Dissolve 0.233g fumaric acid and 0.325g FeCl ₃ 6H ₂ O in 20mL N,N-dimethylformamide, stir vigorously to form a transparent yellow solution, then transfer the solution to 50mL polytetrafluoroethylene In a lined stainless steel autoclave, heat at 120°C for 2h, collect the sample by centrifugation after cooling, alternately wash with water and ethanol three times, and dry at 60°C for 12h to obtain an iron-based metal-organic framework.

S2. Ultrasonic disperse 60 mg of iron-based metal-organic framework in 20 mL of ethanol for 5 min to form solution A, then dissolve 250 mg of Co(NO ₃ ) ₂ 6H ₂ O and 750 mg of urea in 30 mL of distilled water to form solution B, and dissolve A , B solution is mixed and poured into a 100mL glass bottle with a cover, then put the glass bottle in an oven, heat at 90°C for 5 hours without stirring, after cooling, centrifuge the brown product, wash it with water and ethanol for many times until there is no impurity , and dried at 60°C for 12h to obtain Co-Fe LDH yolk-shell nanocages.

S3. Put Co-Fe LDH egg yolk shell nanocages and selenium powder in the same porcelain boat with a mass ratio of 1:2. The temperature was kept at 350°C for 4h at a heating rate of 2°C min ^-1 , then kept at 400°C for 1.5h at a heating rate of 2°C min ^-1 under a nitrogen atmosphere, and finally cooled with the furnace to obtain the composite material FeSe ₂ @CoSe ₂ /FeSe ₂ heterostructure yolk-shell polyhedra.

<Example 2>

S1. Dissolve 0.245g benzoic acid and 0.581g Ni(NO ₃ ) ₂ 6H ₂ O in 20mL absolute ethanol, stir vigorously to form a transparent green solution, then transfer the solution to 50mL PTFE-lined stainless steel In an autoclave, heat at 110° C. for 5 h, collect the sample by centrifugation after cooling, alternately wash with water and ethanol three times, and dry at 80° C. for 24 h to obtain a nickel-based metal-organic framework.

S2. Ultrasonic dispersion of 60 mg of nickel-based metal-organic framework in 20 mL of methanol for 5 min to form solution A. Dissolve 250mg Co(NO ₃ ) ₂ ·6H ₂ O and 1250mg sodium carbonate in 30mL distilled water to form solution B. Mix A and B solutions and pour them into a 100mL glass bottle with a cover, then put the glass bottle into the oven , heated at 90°C for 5h without stirring, and after cooling, the product was collected by centrifugation, washed with water and ethanol several times until free of impurities, and dried at 60°C for 24h to obtain Co-Ni LDH yolk-shell nanocages.

S3. Put Co-Ni LDH yolk-shell nanocages and selenium powder in the same ceramic boat with a mass ratio of 1:4, and the selenium powder is placed at the upstream end of the tube furnace gas path. Afterwards, it was firstly kept at 300°C for 4 hours at a heating rate of 5°C min ^-1 under a hydrogen/argon mixed atmosphere, then kept at 500°C at a heating rate of 5°C min ^-1 under an argon atmosphere for 5 hours, and finally cooled in the furnace , to obtain composite NiSe ₂ @CoSe ₂ /NiSe ₂ heterostructure yolk-shell polyhedra.

<Example 3>

S1. Dissolve 0.180g oxalic acid and 0.108g FeCl ₃ 6H ₂ O in 20mL deionized water, stir vigorously to form a transparent yellow solution, then transfer the solution to a 50mL polytetrafluoroethylene-lined stainless steel autoclave, Heating at 120°C for 3 hours, centrifuging to collect samples after cooling, washing with water and ethanol three times alternately, and drying at 60°C for 8 hours to obtain iron-based metal-organic frameworks.

S2. Ultrasonic disperse 60 mg of iron-based metal-organic framework in 20 mL of ethanol for 5 minutes to form solution A, then dissolve 250 mg of C ₄ H ₁₄ MnO ₈ and 250 mg of urea in 30 mL of distilled water to form solution B, and mix A and B solutions Then pour it into a 100mL glass bottle with a lid. Then put the glass bottle into the oven and heat it at 60°C for 12h without stirring. After cooling, the product was collected by centrifugation, washed with water and ethanol several times until no impurities, and dried at 60°C for 8h to obtain the Fe-Mn LDH egg yolk shell nanocage.

S3. Put Fe-Mn LDH yolk-shell nanocages and selenium powder in the same porcelain boat with a mass ratio of 1:1. The temperature was kept at 350 °C for 6 h at a heating rate of 3 °C min ^-1 , and then kept at 500 °C for 6 h at a heating rate of 3 °C min ^-1 under a nitrogen atmosphere, and finally cooled in the furnace to obtain the composite material FeSe ₂ @MnSe ₂ / FeSe ₂ heterostructure yolk-shell polyhedra.

The double transition metals selected in Examples 1, 2, and 3 were iron/cobalt, nickel/cobalt, and iron/manganese, respectively, and the organic ligand reagents selected were fumaric acid, benzoic acid, and oxalic acid, respectively.

<Example 4>

S1. According to the mass ratio of 7:2:1, weigh the composite material prepared by the method described in Example 1, acetylene black, and polyvinylidene fluoride 0.14g, 0.04g, and 0.02g respectively, and dissolve them in 1mL NMP , and mix uniformly in a mixer to obtain electrode slurry.

S2. Coat the mixed electrode slurry evenly on the aluminum foil, place it in a vacuum drying oven and dry it at 100°C for 12 hours, cut into electrode discs with a loading capacity of about 1 mg, and assemble them with CR2032 button cells .

S3. The negative electrode sheet made of composite material is used as the working electrode, the metal sodium sheet is used as the counter electrode, and the glass fiber diaphragm and 1mol L ^- 1 sodium hexafluorophosphate (NaPF ₆ ) are dissolved in diethylene glycol methyl ether (DME). Assemble a battery for the electrolyte and conduct a performance test.

<Example 5>

S1. According to the mass ratio of 5:1:1, weigh the composite material prepared by the method described in Example 1, acetylene black, and polyvinylidene fluoride 0.10g, 0.02g, and 0.02g respectively, and dissolve them in 1mL NMP , and mix uniformly in a mixer to obtain electrode slurry.

S2. Coat the mixed electrode slurry evenly on the aluminum foil, place it in a vacuum drying oven and dry it at 100°C for 12 hours, cut into electrode discs with a loading capacity of about 1 mg, and assemble them with CR2032 button cells .

S3. The negative electrode sheet made of composite material is used as the working electrode, the metal sodium sheet is used as the counter electrode, and the glass fiber diaphragm and 1mol L ^- 1 sodium hexafluorophosphate (NaPF ₆ ) are dissolved in diethylene glycol methyl ether (DME). Assemble a battery for the electrolyte and conduct a performance test.

<Example 6>

S1. According to the mass ratio of 5:1:1, weigh the composite material prepared by the method described in Example 1, acetylene black, and polyvinylidene fluoride 0.10g, 0.02g, and 0.02g respectively, and dissolve them in 1mL NMP , and mix uniformly in a mixer to obtain electrode slurry.

S2. Coat the mixed electrode slurry evenly on the aluminum foil, place it in a vacuum drying oven and dry it at 100°C for 12 hours, cut into electrode discs with a loading capacity of about 1 mg, and assemble them with CR2032 button cells .

S3. The negative plate made of composite material is used as the working electrode, the sodium vanadium phosphate material is used as the counter electrode, and the glass fiber diaphragm and 1mol L ^-1 sodium hexafluorophosphate (NaPF ₆ ) are dissolved in diethylene glycol methyl ether (DME ) for the electrolyte to assemble into a battery and perform a performance test.

<Example 7>

S1. According to the mass ratio of 7:2:1, weigh the composite material prepared by the method described in Example 1, acetylene black, and polyvinylidene fluoride 0.14g, 0.04g, and 0.02g respectively, and dissolve them in 1mL NMP , and mix uniformly in a mixer to obtain electrode slurry.

S2. Coat the mixed electrode slurry evenly on the aluminum foil, place it in a vacuum drying oven and dry it at 100°C for 12 hours, cut into electrode discs with a loading capacity of about 1 mg, and assemble them with CR2032 button cells .

S3. The negative plate made of composite material is used as the working electrode, the sodium vanadium phosphate material is used as the counter electrode, and the glass fiber diaphragm and 1mol L ^-1 sodium hexafluorophosphate (NaPF ₆ ) are dissolved in diethylene glycol methyl ether (DME ) for the electrolyte to assemble into a battery and perform a performance test.

<Comparative example 1>

S1. Dissolve 0.233g fumaric acid and 0.325g FeCl ₃ 6H ₂ O in 20mL N,N-dimethylformamide, stir vigorously to form a transparent yellow solution, then transfer the solution into 50mL Teflon In a stainless-steel-lined autoclave, heat at 120°C for 2 hours, collect the sample by centrifugation after cooling, alternately wash with water and ethanol three times, and dry at 60°C for 12 hours to obtain an iron-based metal-organic framework.

S2. Ultrasonic disperse 60 mg of iron-based metal-organic framework in 20 mL of ethanol for 5 minutes to form solution A, then dissolve 750 mg of urea in 30 mL of distilled water to form solution B, mix A and B solutions and pour them into a 100 mL glass bottle with a cover Then put the glass bottle into the oven and heat at 90°C for 5h without stirring. After cooling, the brown product was collected by centrifugation, washed with water and ethanol several times, and dried at 60°C for 12h to obtain ferric hydroxide.

S3, ferric hydroxide and selenium powder are placed in the same porcelain boat with a mass ratio of 1:2, and the selenium powder is placed near the upstream end of the tube furnace. Afterwards, it was firstly incubated at 350°C for 4 hours at a heating rate of 2°C min ^-1 under a mixed atmosphere of hydrogen and argon, and then kept at 400°C for 1.5 hours at a heating rate of 2°C min ^-1 under a nitrogen atmosphere. Finally, it is cooled with the furnace to obtain the target material FeSe ₂ .

<Comparative example 2>

S1. According to the mass ratio of 7:2:1, weigh the composite material prepared by the method described in Comparative Example 1, acetylene black, and polyvinylidene fluoride 0.14g, 0.04g, and 0.02g, respectively, and dissolve them in 1mL NMP , and mix uniformly in a mixer to obtain electrode slurry.

S2. Coat the mixed electrode slurry evenly on the aluminum foil, place it in a vacuum drying oven and dry it at 100°C for 12 hours, cut into electrode discs with a loading capacity of about 1 mg, and assemble them with CR2032 button cells .

S3. The negative electrode sheet made of composite material is used as the working electrode, the metal sodium sheet is used as the counter electrode, and the glass fiber diaphragm and 1mol L ^- 1 sodium hexafluorophosphate (NaPF ₆ ) are dissolved in diethylene glycol methyl ether (DME). Assemble a battery for the electrolyte and conduct a performance test.

Taking the composite material FeSe ₂ @CoSe ₂ /FeSe ₂ obtained in Example 1 as an example, its particle size is about 1-2 μm, and its scanning electron microscope (SEM) and transmission electron microscope (TEM) are shown in Figure 1 and Figure 2 respectively Show.

As shown in Figure 3, the rate performance diagram of the battery assembled in Example 4, the voltage range is 0.3-2.9V, at 0.1Ag ^-1 , 0.2Ag ^-1 , 0.5Ag ^-1 , 1Ag ^-1 , 2Ag ^-1 , The galvanostatic charge and discharge tests were carried out under the current density of 3Ag ^-1 and 5Ag ^-1 , and the discharge specific capacities were 708.8, 550.4, 539.2, 533.6, 522.8, 512.5 and 495.4mAh g ^-1 , showing excellent rate performance.

As shown in Figure 4, the cycle performance diagrams of the assembled batteries prepared in Example 4 and Comparative Example 2 at a low current density ^{of 0.2Ag} The shell-type composite material FeSe ₂ @CoSe ₂ /FeSe ₂ is used as the negative electrode material of the battery, which can make the battery have higher capacity and better stability.

As shown in Figure 5, it is the cycle performance diagram of the battery assembled in Example 4 at a high current density of 2Ag ^-1 . It can be seen from Figure 5 that the material still has a specific capacity of 529mAh g ^-1 after charging and discharging for 1800 times, and the capacity remains The efficiency is as high as 78%, showing excellent cycle performance and long life, and is an ideal anode material for realizing high-capacity, high-power sodium-ion batteries.

In this article, the orientation words such as front, back, upper, and lower involved are defined by the positions of the parts in the drawings and the positions between the parts in the drawings, and the positions between the parts are only for the clarity and convenience of expressing the technical solution. It should be understood that the use of the location words should not limit the scope of protection claimed in this application.

In the case of no conflict, the above-mentioned embodiments and features in the embodiments herein may be combined with each other.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. a preparation method of heterogeneous structure egg yolk shell type double transition metal selenide composite material, is characterized in that, comprises the following steps: S1. Dissolving the organic ligand reagent and TM ₁ source in the reagent, and sequentially subjecting the solution to hydrothermal reaction, cooling, centrifugation, washing and drying, to obtain a transition metal-organic framework; wherein the TM ₁ source is Ti One or more of nitrate, phosphate, sulfate and chloride of Cr, Mn, Fe, Co, Ni, Cu or Zn; S2. Uniformly disperse the transition metal-organic framework prepared in S1 in the reagent to obtain solution A; dissolve the _TM2 source and the precipitating agent in the reagent to obtain solution B; after mixing solution A and solution B, pass through heat preservation, cooling, centrifugation, washing and drying to obtain a transition metal-organic framework material coated with a double transition metal hydroxide of an egg yolk shell structure; the TM _source is Ti, Cr, Mn, Fe, Co, Ni, One or more of nitrate, phosphate, sulfate and chloride of Cu or Zn; S3. Under the protection of an inert gas, the transition metal-organic framework material coated with double transition metal hydroxide prepared in S2 is annealed and heat-treated with a certain proportion of selenium powder, and after cooling in the furnace, the composite material TM ₁ Se ₂ is obtained @TM ₁ Se ₂ /TM ₂ Se ₂ . 2. the preparation method of heterogeneous structure egg yolk shell type double transition metal selenide composite material as _claimed in claim 1, is characterized in that, the ratio of the amount of substance of Tm source and described organic ligand reagent in S1 The ratio is 1~5:5, the temperature of hydrothermal reaction is 100~160°C, the time is 1~5h, the temperature condition of drying is 60~100°C, and the time condition is 8~24h. 3. the preparation method of heterogeneous structure yolk-shell type double transition metal selenide compound material as claimed in claim 1, it is characterized in that, in S2, described precipitation agent, described transition metal-organic framework, described TM _source The mass ratio is 1-5:0.24:1, the temperature condition of heat preservation treatment is 60-90°C, the time condition is 4-12h, the temperature condition of drying is 60-100°C, and the time condition is 8-24h. 4. the preparation method of heterogeneous structure egg yolk shell type double transition metal selenide compound material as claimed in claim 1, is characterized in that, in S3, the transition metal-organic framework of described double transition metal hydroxide coating The mass ratio of the material to the selenium powder is 1:1～4; Place the porcelain boat containing the transition metal-organic framework material coated with the double transition metal hydroxide and the selenium powder in a tube furnace, and first heat it to 200 °C in a hydrogen/argon or hydrogen/nitrogen mixed atmosphere. ~400°C, keep warm for 1~6h; then heat to 400~800°C under nitrogen or argon atmosphere, keep warm for 1~6h, the two-stage heating rate is 2~8°C/min. 5. the preparation method of heterogeneous structure egg yolk shell type double transition metal selenide composite material as claimed in claim 1, is characterized in that, described organic ligand reagent is the in fumaric acid, benzoic acid, oxalic acid, pyrazine one or more; The reagents in S1 and S2 are one or more of deionized water, methanol, ethanol, N,N-dimethylformamide, N,N-diethylformamide, acetonitrile, and acetone; The precipitant includes one or more of ammonium chloride, urea, sodium hydroxide, and sodium carbonate. 6. The heterogeneous structure yolk-shell type double-transition metal selenide composite material prepared by the preparation method according to any one of claims 1-5. 7 . The yolk-shell double-transition metal selenide composite material with heterogeneous structure according to claim 6 , wherein the composite material has a hollow yolk-eggshell structure, and the particle size is 1-2 microns. 8. The application of the heterostructure yolk-shell type double transition metal selenide composite material as claimed in claim 7 in the preparation of negative electrode active materials for sodium ion batteries. 9. A sodium-ion battery, characterized in that, comprises an electrode sheet, a counter electrode, a diaphragm and an electrolyte, wherein the electrode sheet is composed of a heterogeneous structure egg yolk shell type double transition metal selenide compound according to claim 7 The material is mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 5-7:1-2:1, the counter electrode is a sodium metal sheet, the diaphragm is a glass fiber diaphragm, and the electrolyte consists of 1mol ·L ^-1 Sodium hexafluorophosphate is prepared by dissolving diethylene glycol methyl ether. 10. A sodium-ion battery, characterized in that, comprises an electrode sheet, a counter electrode, a diaphragm and an electrolyte, wherein the electrode sheet is composed of a heterogeneous structure egg yolk shell type double transition metal selenide compound according to claim 7 The material is mixed with acetylene black and polyvinylidene fluoride at a mass ratio of 5 to 7:1 to 2:1, the counter electrode is a sodium vanadium phosphate positive electrode material, the diaphragm is a glass fiber diaphragm, and the electrolyte It is obtained by dissolving 1mol·L ^-1 sodium hexafluorophosphate in diethylene glycol methyl ether.

Images