Amorphous double-metal sulfide material, preparation method, electrode material and application

Abstract

The application relates to the technical field of batteries, and particularly discloses an amorphous bimetal sulfide material, a preparation method, an electrode material and applications. The preparation method selects two metal elements with certain synergistic effects to prepare a DMF homogeneous polymer, combines an alkaline non-solvent induced phase separation method, and then regulates and controls pre-oxidation, sulfuration and carbonization and cooling processes to obtain an amorphous bimetal sulfide material which can be applied to lithium and sodium ion batteries and has excellent electrochemical performance. In particular, the two different metal elements can break through the limit of the theoretical capacity of a single metal element and further break through the existing specific capacity limit; a step-by-step sulfuration and carbonization process is adopted, a stable and sufficient sulfuration process is first carried out, and then a carbonization process with a short time is carried out; after the carbonization process is completed, a cooling process is immediately carried out, so that the crystal is difficult to nucleate and crystallize and grow, thereby preparing nanoscale amorphous particles, and the volume expansion rate is fundamentally reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, and discloses an amorphous double-metal sulfide material for manufacturing an electrode material, a preparation method, an electrode material and application. BACKGROUND

[0002] Lithium and sodium ion batteries, as the most promising rechargeable batteries in energy storage devices, have attracted extensive attention and research. As the core component of energy storage devices, electrode materials bear electrochemical reactions and play the roles of ion and electron transmission. The research and development of negative electrode materials, as an important part of electrode materials, are particularly important. By selecting a suitable negative electrode material, the electrochemical performance can be improved while the cost is reduced.

[0003] The application with the publication number CN117747849A discloses a flow battery multi-scale electrode and method based on non-solvent induced phase separation, which specifically comprises the following steps: S1, adding dimethylformamide solvent to the mixed powder of polyacrylonitrile and polyvinylpyrrolidone, uniformly stirring in an oil bath to obtain a clear yellowish viscous solution; S2, uniformly pouring the obtained yellowish viscous solution into a mold, first pretreating the mold containing the solution, then immersing the mold in a constant-temperature water bath for phase separation to obtain a small-scale porous polymer matrix for preparing a porous electrode; S3, wiping dry the obtained polymer matrix and clamping it between two aluminum oxide ceramic sheets, placing the completely dried polymer matrix and the two aluminum oxide ceramic sheets clamped on both sides into a muffle furnace for pre-carbonization, then transferring them into a tube furnace for carbonization treatment in a nitrogen environment; S4, based on the simulation results of the pore scale model, perforating the product obtained in S3 by infrared laser to realize the processing of large-scale pores in the multi-scale electrode, thereby completing the preparation of the multi-scale electrode. The application discloses a new type of multi-scale electrode structure based on the non-solvent induced phase separation technology and the infrared laser perforation technology, and cooperates with the typical symmetrical structure of the cross-type flow channel. The application belongs to the field of flow batteries and cannot effectively solve the problems in the field of lithium and sodium ion batteries.

[0004] The application with the publication number CN115602845A discloses a modified graphene negative electrode material, a preparation method thereof, a negative electrode sheet and a battery. The method specifically comprises the following steps: mixing and stirring modified graphene obtained by esterification modification of carboxylated graphene, polyvinylpyrrolidone and tetrahydrofuran to obtain a homogeneous solution; after adjusting the pH of the homogeneous solution to weak acidity by adding glacial acetic acid, gradually adding a mixed solution of titanate and anhydrous ethanol to form a gelation system, and then using a non-solvent induced phase separation method to precipitate a porous graphene precipitate in which titanium dioxide is deposited. The selected modified graphene material only has good performance improvement in the application field of lithium ion batteries and is not involved in the field of sodium ion batteries.

[0005] Xiao Tien of Central South University published a paper in the Journal of Energy Storage entitled "In-situ growth of flake SnS in three-dimensional hierarchical porous carbon boosting lithium storage performance, Journal of Energy Storage, Volume 78, 2024, 109897, ISSN 2352-152X". The paper discloses a crystalline tin sulfide grown on the surface of a hierarchical porous carbon matrix, and achieves excellent performance in the field of lithium ion batteries. As a lithium ion battery, it can maintain a discharge specific capacity of 917.6 mAhg -1 at a current density of 0.1 Ag -1 after 100 cycles, but the final product in the paper has a high carbon content and generates crystalline tin sulfide, and the effective charge and discharge active sites are insufficient.

[0006] In summary, there is an urgent need for a material that can be applied to lithium and sodium ion batteries and has good electrochemical performance to solve the problems in the prior art. SUMMARY

[0007] The purpose of the present application is to provide an amorphous double metal sulfide material that can be applied to lithium and sodium ion batteries and has good electrochemical performance after being made into an electrode material. The specific technical solutions are as follows:

[0008] An amorphous double metal sulfide material, the chemical structure formula of which is represented as MS / NS@HPC, wherein: M and N are two different transition metals selected from V, Cr, Cu, Zr, Sn, Zn, Fe, Co, Mo, Ti, Ni and Mn; MS / NS is a composite amorphous double metal sulfide material; and HPC is a hierarchical porous carbon matrix, which has a hierarchical porous structure under SEM observation.

[0009] Preferably, the mass of HPC is not more than 25% of the total mass of the composite amorphous double metal sulfide material; the amorphous double metal sulfide material is a particle with a size of 8-12 nm, which is located inside the hierarchical porous carbon matrix.

[0010] The present application also discloses a preparation method of the amorphous double metal sulfide material, comprising the following steps:

[0011] Step one, preparing DMF homogeneous polymer, specifically: adding M metal salt and N metal salt into dimethylformamide in proportion, stirring uniformly to obtain a first mixed solution; adding polyacrylonitrile and polyvinylpyrrolidone into the first mixed solution in turn under stirring to obtain DMF homogeneous polymer;

[0012] Step two, preparing hierarchical porous precursor, specifically: adding DMF homogeneous polymer into non-solvent liquid in alkaline environment under stirring, and then washing and drying to obtain hierarchical porous precursor;

[0013] Step three, preparing amorphous double-metal sulfide material, specifically comprising:

[0014] Step 3.1, pre-oxidation treatment, specifically: pre-oxidizing the hierarchical porous precursor to obtain pre-oxidized precursor;

[0015] Step 3.2, sulfuration and carbonization treatment, specifically: under the protection of inert gas, first performing sulfuration reduction reaction of the pre-oxidized precursor and sulfur source at T1 temperature, and then performing carbonization treatment at T2 temperature to obtain sulfuration and carbonization product; T1+340℃<T2;

[0016] Step 3.3, cooling treatment, specifically: cooling the sulfuration and carbonization product by using cooling reagent to obtain amorphous double-metal sulfide material; the chemical structural formula of the amorphous double-metal sulfide material is represented as MS / NS@HPC, wherein: M and N are two different transition metal elements selected from V, Cr, Cu, Zr, Sn, Zn, Fe, Co, Mo, Ti, Ni and Mn.

[0017] The present application selects two metal elements with certain synergistic effect to prepare DMF homogeneous polymer, combines non-solvent liquid in alkaline environment as reagent of non-solvent induced phase separation method, and then obtains amorphous double-metal sulfide material with good electrical performance applied in lithium and sodium ion batteries by regulating pre-oxidation, sulfuration and carbonization processes. In particular, two different metal elements can break through the limit of theoretical capacity of single metal element and further break through the limit of existing specific capacity; the step-by-step sulfuration and carbonization process is adopted, first performing stable and sufficient sulfuration process, and then performing short carbonization process; immediately performing cooling process after the completion of carbonization process, so that crystal nucleation and crystallization growth are difficult, thereby preparing nanoscale amorphous particles and fundamentally reducing volume expansion rate.

[0018] Preferably, in the step one, the M metal salt and the N metal salt are two of ferrous chloride tetrahydrate, stannous chloride dihydrate, nickel chloride hexahydrate, copper chloride dihydrate, zinc sulfate heptahydrate, vanadyl sulfate, cobalt chloride hexahydrate, zirconium nitrate trihydrate, chromium chloride hexahydrate, molybdenum trichloride, titanyl sulfate, and manganese chloride tetrahydrate, and the molar ratio of the M element in the M metal salt to the N element in the N metal salt is 1:1; the mass ratio of the polyacrylonitrile to the polyvinylpyrrolidone is 4:1; and the total mass of the polyacrylonitrile and the polyvinylpyrrolidone is half of the mass of the composite amorphous bimetallic sulfide material MS / NS.

[0019] Preferably, in the step two, the non-solvent liquid in the alkaline environment contains at least one of potassium hydroxide, sodium hydroxide, aqueous ammonia, sodium carbonate, and sodium bicarbonate; the DMF homopolymer is added to the non-solvent liquid in the alkaline environment at a drop rate of 1-2 ml / min; the stirring speed is 300-400 rpm; the washing is specifically repeated 3-6 times using deionized water; and the drying is specifically freeze-drying for 24 h-48 h using a freeze dryer.

[0020] Preferably, in the step two, the hierarchical porous precursor contains a hierarchical porous carbon matrix and metal oxides and / or metal hydroxides encapsulated inside the hierarchical porous carbon matrix, the metal oxides contain at least one of M oxide and N oxide, and the metal hydroxides contain at least one of M hydroxide and N hydroxide.

[0021] Preferably, in the step three, in the pre-oxidation process, the temperature is raised to 260℃-270℃ at a heating rate of 0.5℃-1℃ / min and maintained for 2 h-3 h; in the sulfidation and carbonization process, the temperature is raised to 220℃-300℃ at a heating rate of 1℃-2℃ / min and maintained for 0.5 h-1 h for a sulfidation and reduction reaction, the sulfur source is at least one of thiourea and sulfur powder, the mass ratio of the sulfur source to the pre-oxidized precursor is 5:1, the temperature is raised to 650℃-800℃ at a heating rate of 3℃-5℃ / min, and the carbonization process is ended; the inert gas is at least one of argon, hydrogen-argon, and nitrogen, the argon accounts for 95% and the hydrogen accounts for 5% in the hydrogen-argon; and in the cooling process, the sulfidation and carbonization product is placed in a container, liquid nitrogen is poured into the container for sealing, and the cooling is performed at a cooling rate of 50℃-80℃ / sec.

[0022] Preferably, in the sulfidation process, when the thiourea is used for sulfidation, the thiourea is placed in the upstream of the tube furnace, and the pre-oxidized precursor is placed in the downstream of the tube furnace, the thiourea is decomposed to generate a substance containing hydrogen sulfide, which diffuses downstream with the continuously introduced inert gas, and the sulfidation and reduction reaction occurs with the pre-oxidized precursor; when the sulfur powder is used for sulfidation, the sulfur powder is mixed uniformly with the pre-oxidized precursor and placed in the downstream of the tube furnace, and the sulfidation and reduction reaction occurs with the pre-oxidized precursor.

[0023] The present invention also discloses an electrode material, which is made from an amorphous bimetallic sulfide material obtained by the above-described preparation method.

[0024] The present invention also discloses an application of the above-mentioned electrode material, wherein the electrode material is applied to lithium-ion batteries and / or sodium-ion batteries.

[0025] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1(a) is a SEM image of the amorphous bimetallic sulfide material of Example 1 of the present invention;

[0028] Figure 1(b) is a SEM image of the amorphous bimetallic sulfide material in Comparative Example 1;

[0029] Figure 2(a) shows the electrode material in 2Ag in Embodiment 1 of the present invention. -1 The cycle performance curves of lithium-ion batteries at current densities;

[0030] Figure 2(b) shows the electrode material in Comparative Example 1 under 2Ag conditions. -1 The cycle performance curves of lithium-ion batteries at current densities;

[0031] Figure 3(a) shows the electrode material in Example 1 of the present invention at 1Ag. -1 Cyclic performance curves of sodium-ion batteries at current densities;

[0032] Figure 3(b) shows the electrode material in Comparative Example 1 at 1Ag. -1 Cyclic performance curves of sodium-ion batteries at current densities;

[0033] Figure 4(a) is a thermogravimetric analysis curve of Embodiment 1 of the present invention;

[0034] Figure 4(b) is a thermogravimetric analysis curve of Comparative Example 1. Detailed Implementation

[0035] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered by the claims.

[0036] Example 1:

[0037] An amorphous double-metal sulfide material, a chemical structural formula of which is represented as MS / NS@HPC, wherein: M and N are two different transition metals in V, Cr, Cu, Zr, Sn, Zn, Fe, Co, Mo, Ti, Ni and Mn; MS / NS is a composite amorphous double-metal sulfide material; HPC is a hierarchical porous carbon matrix, a mass of the HPC is not more than 25% of a total mass of the composite amorphous double-metal sulfide material; the amorphous double-metal sulfide material is a particle of 8-12 nm, which is located inside the hierarchical porous carbon matrix.

[0038] The preparation method of the amorphous double-metal sulfide material comprises the following steps:

[0039] Step one, preparing a DMF homogeneous polymer, specifically: M metal salt and N metal salt are proportionally put into dimethylformamide and stirred uniformly to obtain a first mixed solution; polyacrylonitrile and polyvinylpyrrolidone are sequentially added to the first mixed solution under stirring to obtain the DMF homogeneous polymer.

[0040] In this embodiment, the molar ratio of the M metal salt and the N metal salt is 1:1, specifically, 2.25 g of stannous chloride dihydrate and 2.07 g of zinc sulfate heptahydrate are used; dimethylformamide (DMF) is 25 ml; the first mixed solution is obtained by quickly dissolving at room temperature with a stirring speed of 600 rpm until the dimethylformamide becomes clear and transparent again; under the condition of keeping sufficient stirring, polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP) are sequentially added, the mass ratio of polyacrylonitrile to polyvinylpyrrolidone is 4:1; the total mass of polyacrylonitrile and polyvinylpyrrolidone is half of the mass of the composite amorphous double-metal sulfide material MS / NS, here, 0.6 g of polyacrylonitrile (PAN) and 0.15 g of polyvinylpyrrolidone (PVP) are sequentially added, and then the mixture is placed in a water bath at 80℃ for 40 min of water bath heating with a stirring speed of 600 rpm; after the water bath program is completed, the homogeneous polymer is continuously stirred and mixed at room temperature for 12 h to obtain the DMF homogeneous polymer.

[0041] Step two, preparing a hierarchical porous precursor, specifically: the DMF homogeneous polymer is added to a non-solvent liquid in an alkaline environment under stirring, and after the addition is completed, washing and drying are performed to obtain the hierarchical porous precursor.

[0042] The preferred embodiment of the present application is that the DMF homogenous polymer is dropped into 0.5 mol / L potassium hydroxide liquid at a speed of 1 ml / min using a needle with a 0.5 mm caliber. The polymer is prevented from agglomerating by constant stirring at a speed of 400 rpm. After the dropping of the DMF homogenous polymer is completed, the stirring is stopped and the alkaline non-solvent liquid in the container is removed. The primary product remaining in the container is washed repeatedly with deionized water for 3 times, and then is subjected to 24 h of freeze-drying using a freeze-drying machine, and finally a hierarchical porous precursor is obtained, and the hydroxides of tin and iron metals are encapsulated in the polyacrylonitrile precursor skeleton.

[0043] Step three, preparation of amorphous double-metal sulfide material, specifically comprising:

[0044] Step 3.1, pre-oxidation treatment, specifically: the hierarchical porous precursor is subjected to pre-oxidation treatment to obtain a pre-oxidized precursor.

[0045] The preferred embodiment of the present application is that the hierarchical porous precursor is subjected to pre-oxidation treatment using a muffle furnace. The temperature is raised to 260°C at a heating rate of 0.5°C / min and is maintained for 2 h.

[0046] Step 3.2, sulfidation and carbonization treatment, specifically: under the protection of inert gas, the pre-oxidized precursor is first subjected to sulfidation reduction reaction with a sulfur source at T1 temperature, and then is subjected to carbonization treatment at T2 temperature to obtain a sulfidation and carbonization product; T1+340°C

[0047] The preferred embodiment of the present application is that five times the mass of thiourea (CH4N2S) is added to the pre-oxidized double-metal precursor, and the pre-oxidized double-metal precursor is placed in the upstream of the tube furnace and the thiourea is placed in the downstream of the tube furnace. Under the protection of argon, the temperature is raised to 250°C at a heating rate of 1°C / min and is maintained for 0.5 h to complete the sulfidation treatment. Subsequently, the heating rate is changed to 3°C / min to raise the temperature to 750°C to complete the carbonization treatment.

[0048] Step 3.3, cooling treatment, specifically: the sulfidation and carbonization product is subjected to cooling treatment using a cooling reagent to obtain an amorphous double-metal sulfide material.

[0049] The preferred embodiment of the present application is that the product is rapidly cooled by liquid nitrogen after the tube furnace temperature maintaining program is completed.

[0050] The electrode material preparation technology used for the electrode material made of the above-mentioned amorphous double-metal sulfide material is a conventional technology, and the purpose is to prove the feasibility of the self-growth of the amorphous double-metal sulfide material in the hierarchical porous carbon matrix by the above-mentioned preparation method based on data examples.

[0051] Negative electrode slurry preparation process: The final product was ground into powder by mortar and pestle, and was ground with acetylene black (ACET), polyacrylic acid (PAA) according to a mass ratio of 7:2:1 for 40 min, followed by dropwise addition of N-methyl pyrrolidone (NMP) solution. After stirring at room temperature for 12 h, a working electrode slurry was formed. The negative electrode slurry was uniformly coated on a clean copper foil surface by a coating machine, and the average mass loading of the battery electrode sheet was controlled by controlling the coating thickness. Subsequently, vacuum drying was performed in a vacuum drying oven at 90°C for 12 h. After complete drying, the copper foil was punched into a circular electrode sheet using a manual sheet puncher for standby use.

[0052] The lithium and sodium ions were assembled using a CR-2016 size button cell shell, and the entire assembly process was carried out in an argon atmosphere (water and oxygen content less than 0.5 ppm) glove box. The lithium ion half-cell was composed of a bimetallic sulfide electrode as the working electrode, a lithium metal sheet as the counter electrode, and a separator (porous polyethylene). The lithium ion battery electrolyte added during assembly was lithium hexafluorophosphate (LiPF6) with 1.0% vinylene carbonate (VC) by mass ratio and ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate (EC:DEC:EMC) at a volume ratio of 1:1:1. The sodium ion half-cell was composed of a bimetallic sulfide as the working electrode, a sodium metal sheet as the counter electrode, and a separator (glass fiber). The sodium ion battery electrolyte added during assembly was sodium perchlorate (NaClO4) with 5.0% fluoroethylene carbonate (FEC) by mass ratio and ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate (EC:DEC:EMC) at a volume ratio of 1:1:1. Finally, the assembled battery was tightly packaged by a battery packaging machine and left to stand for a period of time to allow the electrolyte to fully soak (lithium ion battery for 24 h, sodium ion battery for 5 h).

[0053] Example 2-3:

[0054] Example 2-3 differs from Example 1 only in the parameters shown in Table 1:

[0055] Table 1: Parameter statistics of Examples 1-3

[0056]

[0057] The SEM images of the amorphous bimetallic sulfide material obtained in Example 2 and Example 3 are similar to those of Example 1.

[0058] Comparative Example 1:

[0059] An amorphous bimetallic sulfide material was prepared as follows:

[0060] First step, preparation of DMF homogenous polymer:

[0061] Into 25ml of dimethylformamide (DMF) was put 5g of metal salt (specifically stannous chloride dihydrate), which was quickly dissolved into dimethylformamide at room temperature with a stirring speed of 600rpm until the dimethylformamide became clear and transparent again. Under the condition of keeping sufficient stirring, 2g of polyacrylonitrile (PAN) and 0.5g of polyvinylpyrrolidone (PVP) were added in sequence, and then the mixture was placed in a water bath at 80℃ for 40min of water bath heating with a stirring speed of 600rpm. After the end of the water bath procedure, the homogeneous polymer was kept at room temperature for 12h of further stirring and mixing.

[0062] Second step, preparation of hierarchical porous precursor:

[0063] The DMF homogeneous polymer after completing sufficient mixing was dropped into deionized water at a speed of 1ml / min using a needle with a diameter of 0.5mm, and stirring was kept during the process to prevent polymer agglomeration, with a stirring speed of 400rpm. After the completion of dropping all the DMF homogeneous polymer, stirring was stopped and the deionized water in the container was removed. The primary product remaining in the container was first washed repeatedly with deionized water for 3 times, and then was subjected to 24h of freeze-drying using a freeze-drying machine, to finally obtain the hierarchical porous precursor, with the hydroxide of tin metal being encapsulated in the polyacrylonitrile precursor skeleton.

[0064] Third step, preparation of amorphous double-metal sulfide material:

[0065] Step ①, pre-oxidation process: the hierarchical porous precursor was subjected to pre-oxidation treatment using a muffle furnace, specifically: heating at a rate of 0.5℃ / min to 260℃ and keeping for 2h.

[0066] Step ②, sulfuration and carbonization process: according to five times the mass, thiocarbamide (CH4N2S) was added to the pre-oxidized tin metal precursor, and the pre-oxidized precursor was placed downstream of the tube furnace, under the protection of argon, and was directly heated at a rate of 2℃ / min to 550℃ and kept for 3h.

[0067] Step ③, cooling process: furnace cooling, specifically: after the end of the sulfuration and carbonization process, the tube furnace was naturally cooled, with the purpose of preparing a crystalline single-metal sulfide for comparison.

[0068] The electrode material was prepared using the above amorphous double-metal sulfide material, in the same manner as in Example 1.

[0069] Comparative Examples 2-5:

[0070] Comparative Examples 2-5 differed from Comparative Example 1 in Table 2:

[0071] Table 2: Parameter statistics of Comparative Examples 1-5

[0072]

[0073]

[0074] The prepared negative electrode material Example 1 and Comparative Example 1 were subjected to phase analysis characterization and electrochemical performance test, and the test results are as follows:

[0075] In combination with FIG. 1(a) and FIG. 1(b): As can be seen from FIG. 1(a), the amorphous tin-zinc sulfide in Example 1 does not grow on the surface of the hierarchical porous carbon matrix; as can be seen from FIG. 1(b), the crystalline stannous sulfide in Comparative Example 1 grows on the surface of the hierarchical porous carbon matrix.

[0076] In combination with FIG. 2(a) and FIG. 2(b): Comparing FIG. 2(a) and FIG. 2(b), the lithium ion battery was tested at a current density of 2 Ag -1 for the cycle performance of 500 cycles in Example and Comparative Example 1, and it can be seen that, whether it is the first cycle charge and discharge capacity, the discharge specific capacity after 500 cycles, or the stability of the discharge specific capacity, the example is better than the comparative example.

[0077] In combination with FIG. 3(a) and FIG. 3(b): Comparing FIG. 3(a) and FIG. 3(b), the sodium ion battery was tested at a current density of 1 Ag -1 for the cycle performance of 500 cycles in Example and Comparative Example 1, and it can be seen that, whether it is the first cycle charge and discharge capacity, the discharge specific capacity after 500 cycles, or the stability of the discharge specific capacity, the example is better than the comparative example.

[0078] In combination with FIG. 4(a) and FIG. 4(b): The carbon content ratio in the amorphous bimetallic sulfide material obtained in Example 1 shown in FIG. 4(a) is only 21.2%, which is much lower than the carbon content ratio of 48.2% in the amorphous bimetallic sulfide material obtained in Comparative Example 1 shown in FIG. 4(b), which can fully illustrate that the alkaline non-solvent environment causes less metal ion loss, and most of them are stored in the carbon matrix skeleton.

[0079] The prepared negative electrode material Example 1-3 and Comparative Example 1-5 were subjected to phase analysis characterization and electrochemical performance test, and the results are shown in Table 3 and Table 4:

[0080] Table 3: Electrochemical performance test data table of Example 1-3 and Comparative Example 1-5

[0081]

[0082] Table 4: Phase analysis characterization data table of Example 1-3 and Comparative Example 1-5

[0083] Case / Characterization Crystal structure of final product Thermogravimetric analysis of carbon content after sulfidation, carbonization process Example 1 Amorphous 21.2％ Example 2 Amorphous 22.3％ Example 3 Amorphous 19.4％ Comparative Example 1 Crystalline 48.2％ Comparative Example 2 Structure collapse 23.8％ Comparative Example 3 Crystalline 22.6％ Comparative Example 4 Crystalline 20.1％ Comparative Example 5 Crystalline 24.7％

[0084] From Table 2, Table 3 and Table 4, it can be seen that:

[0085] Comparative Example 2 differs from Example 1 in that: single metal and no pre-oxidation step. The role of pre-oxidation is to prevent the collapse of the hierarchical porous structure formed in the precursor stage. Comparative Example 2 did not perform the pre-oxidation step, and due to the rapid heating rate in the sulfidation and carbonization stages, the structure collapsed, and finally no complete morphology structure was formed, and no electrochemical performance test was performed. In Example 1, the phase separation step was performed in an alkaline non-solvent environment, which can effectively inhibit the loss of metal ions, and finally all are sealed into the hierarchical porous precursor.

[0086] Comparative Example 3 differs from Example 1 in that: the sulfidation and carbonization process is performed in one step. In Comparative Example 3, the sulfidation and carbonization process at a higher temperature for a long time leads to crystal nucleation and crystal growth, and finally forms a crystalline structure, and the electrochemical performance of lithium and sodium ion batteries is poor. In Example 1, the phase separation step is performed in an alkaline non-solvent environment, which can effectively inhibit the loss of metal ions, and finally all are sealed into the hierarchical porous precursor.

[0087] Comparative Example 4 differs from Example 1 in that: three kinds of metal salts are used. In Comparative Example 4, the addition of more metal elements has limited performance improvement, and it is difficult to control the nucleation and growth of multiple metal sulfides, resulting in the formation of a crystalline structure and poor electrochemical performance of lithium and sodium ion batteries. In Example 1, the phase separation step is performed in an alkaline non-solvent environment, which can effectively inhibit the loss of metal ions, and finally all are sealed into the hierarchical porous precursor.

[0088] Comparative Example 5 differs from Example 1 in that: four kinds of metal salts are used. In Comparative Example 5, the addition of more metal elements has limited performance improvement, and it is difficult to control the nucleation and growth of multiple metal sulfides, resulting in the formation of a crystalline structure and poor electrochemical performance of lithium and sodium ion batteries. In Example 1, it can be seen that the phase separation step is performed in an alkaline non-solvent environment, which can effectively inhibit the loss of metal ions, and finally all are sealed into the hierarchical porous precursor.

[0089] Based on the above:

[0090] 1. Consideration of lithium and sodium ion battery applications: In the process of non-solvent induced phase separation in the present application, an alkaline non-solvent environment is created, which can promote the hydrolysis of metal ions, thereby forming metal hydroxide / oxide products. These hydrolysis products will be sealed on the precursor skeleton, thereby preventing the loss of a large amount of soluble metal ions. The final product after pre-oxidation, sulfidation, carbonization and cooling processes has more electrochemically active sites, and can be applied in both lithium and sodium ion battery fields.

[0091] 2. Two different metal elements produce synergistic effect: In the present application, two different metal elements are combined with the hierarchical porous carbon matrix in the precursor preparation process. Due to the different physical and chemical properties of the two different metal elements, the limit of the theoretical capacity of a single metal element can be broken through, and the existing specific capacity limit can be further broken through.

[0092] 3. The size of the amorphous structure is nanoscale, and the volume expansion is slowed down: The amorphous bimetallic sulfide material formed by the pre-oxidation, carbon sulfuration and cooling process has a nanoscale size. Compared with single metal sulfide, the amorphous bimetallic sulfide material is easy to grow to a size of several orders of magnitude smaller than micron size, has a larger specific surface area and more reaction active sites, and the electrochemical performance can be greatly improved. At the same time, the volume expansion brings smaller influence, and the electrochemical cycle performance is better.

[0093] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An amorphous double metal sulfide material, characterized in that, The chemical structural formula of the amorphous bimetallic sulfide material is represented as MS / NS@HPC, wherein: M and N are two different transition metal elements in V, Cr, Cu, Zr, Sn, Zn, Fe, Co, Mo, Ti, Ni and Mn; MS / NS is a composite amorphous bimetallic sulfide material; and HPC is a hierarchical porous carbon matrix. The mass of the HPC is not more than 25% of the total mass of the composite amorphous bimetallic sulfide material; the amorphous bimetallic sulfide material is 8-12 nm particles located inside the hierarchical porous carbon matrix.

2. A method of preparing an amorphous double metal sulfide material, characterized by, The method comprises the following steps: Step 1: preparing a DMF homogeneous polymer, specifically: adding M metal salt and N metal salt into dimethylformamide in a certain proportion and stirring uniformly to obtain a first mixed solution; adding polyacrylonitrile and polyvinylpyrrolidone into the first mixed solution under stirring to obtain the DMF homogeneous polymer; Step 2: preparing a hierarchical porous precursor, specifically: adding the DMF homogeneous polymer into a non-solvent liquid in an alkaline environment under stirring, and then washing and drying to obtain the hierarchical porous precursor; Step 3: preparing the amorphous bimetallic sulfide material, specifically comprising: Step 3.1: pre-oxidation treatment, specifically: pre-oxidizing the hierarchical porous precursor to obtain a pre-oxidized precursor; Step 3.2: sulfidation and carbonization treatment, specifically: under the protection of an inert gas, first performing a sulfidation reduction reaction on the pre-oxidized precursor with a sulfur source at a T1 temperature, and then performing carbonization treatment at a T2 temperature to obtain a sulfidation and carbonization product; T1+340℃<T2; during the sulfidation and carbonization treatment: the temperature is raised to 220-300℃ at a temperature rising rate of 1-2℃ / min in the inert gas and is kept for 0.5-1h to perform the sulfidation reduction reaction; the temperature is raised to 650-800℃ at a heating rate of 3-5℃ / min in the inert gas to end the carbonization treatment; Step 3.3: cooling treatment, specifically: cooling the sulfidation and carbonization product with a cooling reagent to obtain the amorphous bimetallic sulfide material; the chemical structural formula of the amorphous bimetallic sulfide material is represented as MS / NS@HPC, wherein: M and N are two different transition metal elements in V, Cr, Cu, Zr, Sn, Zn, Fe, Co, Mo, Ti, Ni and Mn.

3. The production method according to claim 2, characterized by, In step 1: the M metal salt and the N metal salt are two of ferrous chloride tetrahydrate, stannous chloride dihydrate, nickel chloride hexahydrate, copper chloride dihydrate, zinc sulfate heptahydrate, vanadyl sulfate, cobalt chloride hexahydrate, zirconium nitrate trihydrate, chromium chloride hexahydrate, molybdenum trichloride, titanium sulfate and manganese chloride tetrahydrate; the molar ratio of the M element in the M metal salt to the N element in the N metal salt is 1:1; the mass ratio of the polyacrylonitrile to the polyvinylpyrrolidone is 4:1; and the total mass of the polyacrylonitrile and the polyvinylpyrrolidone is half of the mass of the composite amorphous bimetallic sulfide material MS / NS.

4. The production method according to claim 2, characterized by, In the second step, the non-solvent liquid in the alkaline environment contains at least one of potassium hydroxide, sodium hydroxide, ammonia, sodium carbonate and sodium bicarbonate; the DMF homogenous polymer is added to the non-solvent liquid in the alkaline environment at a drop rate of 1-2 ml / min; the stirring speed is 300-400 rpm; the washing is specifically repeated 3-6 times with deionized water; and the drying is specifically freeze-drying for 24 h-48 h using a freeze dryer.

5. The preparation method according to claim 2, characterized in that, In the second step, the hierarchical porous precursor contains a hierarchical porous carbon matrix and metal oxides and / or metal hydroxides encapsulated inside the hierarchical porous carbon matrix, the metal oxides contain at least one of M oxide and N oxide, and the metal hydroxides contain at least one of M hydroxide and N hydroxide.

6. The preparation method according to claim 2, characterized in that, In the third step, the pre-oxidation treatment is performed by heating to 260-270 °C at a heating rate of 0.5-1 °C / min in air and holding for 2-3 h; in the sulfuration and carbonization treatment, the sulfur source is at least one of thiourea and sulfur powder, the mass ratio of the sulfur source to the pre-oxidized precursor is 5:1; the inert gas is at least one of argon, hydrogen-argon gas and nitrogen, the hydrogen-argon gas contains 95% argon and 5% hydrogen; and in the cooling treatment, the sulfuration and carbonization product is placed in a container, liquid nitrogen is poured into the container and sealed, and the cooling is performed at a cooling rate of 50-80 °C / s.

7. The preparation method according to claim 6, characterized in that, In the sulfuration process using thiourea, the thiourea is placed upstream of the tube furnace, and the pre-oxidized precursor is placed downstream of the tube furnace, the thiourea decomposes to generate a substance containing hydrogen sulfide which diffuses downstream with the continuously introduced inert gas, and a sulfuration and reduction reaction occurs between the pre-oxidized precursor and the substance containing hydrogen sulfide; In the sulfuration process using sulfur powder, the sulfur powder is mixed uniformly with the pre-oxidized precursor and placed downstream of the tube furnace, and a sulfuration and reduction reaction occurs between the sulfur powder and the pre-oxidized precursor.

8. An electrode material, characterized by The electrode material is made of the amorphous double-metal sulfide material obtained by the preparation method of any one of claims 2-7.

9. Use of an electrode material as claimed in claim 8, characterized in that The electrode material is applied to lithium ion batteries and / or sodium ion batteries. The electrode material is applied to lithium ion batteries and / or sodium ion batteries.

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