Antiperovskite-type positive electrode material and preparation method thereof, and lithium-ion battery

Abstract

The present application relates to an antiperovskite cathode material and a preparation method thereof, and a lithium-ion battery, belonging to the technical field of lithium batteries. The preparation method comprises: mixing a metal salt containing metal M with ethanethiol and water, performing a hydrolysis reaction to obtain a product solution; adjusting the pH of the product solution to 2-4, adding a metal salt containing metal N, lithium ethoxide, a polymerization monomer, a crosslinking agent, and an initiator to the product solution for polymerization reaction to generate a wet gel; drying the wet gel and then heat-treating it to obtain an antiperovskite cathode material Li2M x N y Through this preparation method, the internal particle size of the positive electrode material can be made smaller and the internal particle distribution more uniform, thereby improving the cycle performance and rate performance of the lithium-ion battery.

Description

Technical Field

[0001] The present application relates to the technical field of lithium batteries, and in particular to an antiperovskite-type positive electrode material and a preparation method thereof, and a lithium-ion battery. Background Art

[0002] In just a few decades of development, lithium-ion batteries have become crucial in electronics, transportation, aerospace, and other fields. Generally speaking, a lithium-ion battery consists of a cathode, electrolyte, separator, anode, and current collector. Of these components, the cathode material is the primary factor limiting capacity and has the highest cost of all battery components. Currently, widely studied cathode materials include the polyanionic olivine-structured LiFePO4, layered LiCoO2, the high-nickel ternary material NCM811, and the spinel-structured LiMn2O4.

[0003] Li represented by polyanionic structure 1-x FePO4, due to its poor ionic and electronic conductivity, usually requires small particles to be coated with carbon, which has problems such as low tap density, low energy density, and poor low temperature performance. 1-x CoO2, because Co itself is easily soluble, expensive and harmful to the environment, has problems such as capacity fading, poor safety, environmental pollution and high cost. 1+x Mn2O4, due to the disproportionate dissolution of Mn, has problems such as short life, poor high-temperature performance, gas generation, and bulging.

[0004] The recently proposed new lithium-ion battery positive electrode material with antiperovskite structure has a high theoretical specific capacity, but it also has various problems: including low voltage platform, inability to fully release capacity, poor cycle performance and rate performance, etc. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of the embodiments of the present application includes providing a method for preparing an antiperovskite-type positive electrode material so that the particle size of the internal particles of the positive electrode material is smaller and the internal particle distribution is more uniform, thereby improving the cycle performance and rate performance of lithium-ion batteries.

[0006] In a first aspect, the present invention provides a method for preparing an antiperovskite cathode material, comprising: mixing a metal salt containing a metal M with ethanethiol and water, performing a hydrolysis reaction to obtain a product solution; adjusting the pH of the product solution to 2-4, adding a metal salt containing a metal N, lithium ethoxide, a polymerization monomer, a crosslinking agent, and an initiator to the product solution for polymerization reaction to generate a wet gel; drying the wet gel and then heat-treating it to obtain an antiperovskite cathode material Li2M x Ny SO; wherein 0<x<1, 0<y<1; M and N are different and are metal elements or metalloid elements other than lithium; the metal salt includes carboxylates and / or alkoxides; and the polymerizable monomer includes a vinyl monomer or an allyl monomer.

[0007] In this preparation method, under the initiation of an initiator, a cross-linking agent is used to cause the free radicals of the polymerizable monomers to undergo a polymerization reaction to form a three-dimensional network gel structure; at the same time, a metal salt containing metal N, lithium ethanolate and a hydrolysis product react to form antiperovskite inorganic particles. Due to the presence of the three-dimensional network structure, the inorganic particles can be prevented from agglomerating, which plays a role in refining the grains and can also make the grains uniformly dispersed in the wet gel; then, after heat treatment, the gelled organic matter is fully volatilized, thereby obtaining nano-sized Li2M x N y SO crystals. Through such a preparation method, the internal particle size of the antiperovskite-type positive electrode material can be made smaller and the internal particle distribution more uniform, thereby improving the cycle performance and rate performance of the lithium-ion battery.

[0008] In some embodiments of the present application, M and N each independently include any one of Na, K, Mg, Ca, Sr, Ba, Zn, Sc, Y, Al, Ga, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Si, Sn and Sb.

[0009] In some embodiments of the present application, the metal salt includes at least one of manganese acetate, sodium acetate, iron ethoxide, and cobalt ethoxide.

[0010] In some embodiments of the present application, the acrylic monomer includes acrylamide.

[0011] In some embodiments of the present application, the vinyl monomer includes any one of ethylene, propylene and acrylic acid.

[0012] After the polymerization reaction, the polymerized monomers form a cross-linked structure that can encapsulate and disperse the particles of the metal salt containing the metal M and the metal salt containing the metal N. This helps increase the uniformity of the material, improve the dispersion of the particles, and refine the grain size, thereby improving the performance of the lithium-ion battery cathode material. Vinyl monomers or propenyl monomers are selected as the polymerized monomers because they can provide the required network structure in this preparation method, which helps improve the material's performance, including particle dispersion and grain refinement, thereby enhancing the performance of the lithium-ion battery cathode material.

[0013] In some embodiments of the present application, the crosslinking agent includes any one of N,N-methylenebisacrylamide and divinyldisiloxane. N,N-methylenebisacrylamide and divinyldisiloxane have high crosslinking ability and can form a three-dimensional network gel structure in the polymerization reaction, which is used to support the antiperovskite crystals dispersed in the wet gel. Due to the presence of the three-dimensional network structure, the agglomeration of the grains can be prevented, and the grain distribution can be more uniform, thereby improving the electrochemical performance of the positive electrode material of the lithium-ion battery. At the same time, these two compounds also have good chemical stability and are not easy to decompose, which is beneficial to improving the cycle life of the material.

[0014] In some embodiments of the present application, the initiator includes ammonium persulfate. Ammonium persulfate is a free radical initiator that can initiate free radical polymerization of the monomers, promoting polymer formation. In this preparation method, it helps form a wet gel and catalyzes the polymerization reaction, ultimately producing a well-structured lithium-ion battery cathode material. Ammonium persulfate is easy to use and highly efficient.

[0015] In some embodiments of the present application, the hydrolysis reaction temperature is 20-25°C and the hydrolysis reaction time is 6-8 hours. Controlling the hydrolysis reaction temperature and time within the above ranges can make the hydrolysis reaction more complete and generate the desired important intermediates or precursors for the preparation of antiperovskite cathode materials.

[0016] In some embodiments of the present application, the polymerization reaction temperature is 20-25°C, and the polymerization reaction time is 10-14 hours. Controlling the polymerization reaction temperature and time within these ranges facilitates better control of the free radical polymerization of the monomers during the reaction. This can slow the polymerization reaction rate, helping to ensure the polymerization process proceeds fully, thereby forming a uniform network structure and achieving a more uniform distribution of particles throughout the wet gel.

[0017] In some embodiments of the present application, the drying temperature is 105-120°C and the drying time is 8-10 hours. Within this temperature range, water can be effectively evaporated from the wet gel, which helps reduce the water content in the material and improve its stability.

[0018] In some embodiments of the present application, the heat treatment temperature is 300-500°C and the heat treatment time is 5-7 hours. Heat treatment at 300-500°C for 5-7 hours can fully volatilize the organic matter remaining in the wet gel, reduce the content of organic residues in the material, and thus improve the thermal stability of the material.

[0019] In some embodiments of the present application, the amount of polymerization monomer added is 20-30% of the total mass of the product solution. Adding 20-30% polymerization monomer is conducive to allowing sufficient monomer to participate in the polymerization reaction and form sufficient cross-linking structure, which can effectively prevent particle aggregation, thereby providing appropriate support and dispersion effects.

[0020] In some embodiments of the present application, the amount of cross-linking agent added is 20-30% of the total mass of the product solution. Adding 20-30% of the cross-linking agent can effectively form a cross-linked structure and increase the stability and durability of the material.

[0021] In some embodiments of the present application, the amount of initiator added is 20-30% of the total mass of the product solution. Adding 20-30% of the initiator is beneficial to the initiation reaction, so that the polymerized monomers form a polymer network structure, and the polymerization reaction is more complete.

[0022] In some embodiments of the present application, the particle size of the antiperovskite cathode material is 50-100 nm.

[0023] In a second aspect, an embodiment of the present application provides an antiperovskite positive electrode material prepared by the above-mentioned preparation method.

[0024] In a third aspect, an embodiment of the present application provides a lithium-ion battery comprising the above-mentioned antiperovskite positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 The antiperovskite cathode material Li2Fe prepared in Example 1 of the present application 0.5 Mn 0.5 XRD pattern of SO;

[0027] Figure 2 The antiperovskite cathode material Li2Fe prepared in Example 1 of the present application 0.5 Mn 0.5 SEM image of SO;

[0028] Figure 3 The charge and discharge curves of a battery prepared using the cathode material provided in Example 1 of the present application;

[0029] Figure 4 This is a rate performance diagram of a battery prepared using the positive electrode material provided in Example 1 of the present application. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0031] The present invention provides a method for preparing an antiperovskite cathode material, comprising:

[0032] (1) A metal salt containing metal M is mixed with ethanethiol and water, and stirred at 20-25°C for 2-3 hours using a magnetic stirrer to perform a hydrolysis reaction to obtain a product solution. The purpose of the hydrolysis reaction is to generate important intermediates or precursors for the preparation of the desired antiperovskite cathode material, which include metal ions (M), sulfide ions (S 2- ), and other possible ions and ligands.

[0033] In the present application, the hydrolysis reaction temperature is 20-25° C., and the hydrolysis reaction time is 6-8 hours. This is equivalent to performing the hydrolysis reaction at room temperature. Controlling the hydrolysis reaction time to 6-8 hours can make the hydrolysis reaction more complete.

[0034] The metal M includes any one of Na, K, Mg, Ca, Sr, Ba, Zn, Sc, Y, Al, Ga, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Si, Sn, and Sb. The metal N includes any one of Na, K, Mg, Ca, Sr, Ba, Zn, Sc, Y, Al, Ga, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Si, Sn, and Sb.

[0035] (2) Using nitric acid to adjust the pH of the product solution to 2-4, a metal salt containing metal N, lithium ethanol, a polymerization monomer, a cross-linking agent and an initiator are added to the product solution to generate a wet gel, and the free radicals of the polymerization monomer undergo a polymerization reaction to form a three-dimensional network structure support dispersed in the wet gel.

[0036] The pH of the product solution is adjusted to 2-4 because under this acidic condition, the hydrolysis reaction and polymerization process can be better controlled, so that the synthesis reaction can proceed smoothly. 2+ ) and sulfide ions (S 2-) is more likely to undergo hydrolysis to generate the desired intermediates. Furthermore, within this pH range, the free radical polymerization of the polymerizable monomers can be better promoted, forming a three-dimensional network structure, which helps prevent particle agglomeration and achieve uniform dispersion of fine grains.

[0037] In the present application, metal salts include carboxylates and / or alkoxides; moreover, the metal salt of metal M can be either a carboxylate or an alkoxide; similarly, the metal salt of metal N and the metal salt of metal M can be either a carboxylate or an alkoxide.

[0038] The metal salt includes, but is not limited to, at least one of manganese acetate, sodium acetate, iron ethoxide, and cobalt ethoxide.

[0039] The polymerizable monomers include vinyl monomers or propenyl monomers; propenyl monomers include but are not limited to acrylamide; vinyl monomers include but are not limited to any one of ethylene, propylene and acrylic acid. After the polymerization reaction of the polymerizable monomers, a cross-linked structure is formed, which can wrap and disperse the particles of the metal salt. This helps to increase the uniformity of the material, improve the dispersion of the particles, and refine the grains, thereby improving the performance of the positive electrode material of the lithium-ion battery. The reason for selecting vinyl monomers or propenyl monomers is because they have good polymerization properties and appropriate chemical properties in the polymerization reaction. These two monomers are generally easy to polymerize and can be polymerized under acidic conditions. In addition, their polymerization reactions can usually be carried out at relatively low temperatures, which is suitable for this application.

[0040] In the present application, the cross-linking agent includes but is not limited to any one of N,N-methylenebisacrylamide and divinyldisiloxane; the initiator includes but is not limited to ammonium persulfate. N,N-methylenebisacrylamide and divinyldisiloxane have high cross-linking ability and can form a three-dimensional network structure in the polymerization reaction to support the antiperovskite crystals dispersed in the wet gel. This helps to prevent the agglomeration of grains and make the grain distribution more uniform, thereby improving the electrochemical performance of the lithium-ion battery positive electrode material. At the same time, these two compounds also have good chemical stability and are not easy to decompose, which is beneficial to improving the cycle life of the material. Ammonium persulfate is a free radical initiator that can initiate the free radical polymerization reaction of the polymerized monomer and promote the formation of the polymer. In this preparation method, it helps to form a wet gel and catalyze the polymerization reaction, ultimately generating a lithium-ion battery positive electrode material with a good structure. Ammonium persulfate is easy to use and has high efficiency.

[0041] In the present application, the amount of polymerization monomer added is 20-30% of the total mass of the product solution; the amount of cross-linking agent added is 20-30% of the total mass of the product solution; and the amount of initiator added is 20-30% of the total mass of the product solution. Adding 20-30% of polymerization monomer is conducive to allowing enough monomers to participate in the polymerization reaction and form sufficient cross-linking structure, which can effectively prevent particle aggregation, thereby providing suitable support and dispersion effects. Adding 20-30% of cross-linking agent can effectively form a cross-linking structure and increase the stability and durability of the material. Adding 20-30% of initiator is conducive to the initiation reaction, so that the polymerization monomer forms a polymer network structure, and the polymerization reaction is more complete.

[0042] In the present application, the polymerization reaction temperature is 20-25°C, and the polymerization reaction time is 10-14 hours. Controlling the polymerization reaction temperature and time within these ranges facilitates better control of the free radical polymerization of the monomers during the reaction. This can slow the polymerization reaction rate, helping to fully progress the polymerization process, thereby forming a uniform network structure and achieving a more uniform distribution of particles throughout the wet gel.

[0043] (3) The wet gel is dried and then heat treated to obtain the antiperovskite cathode material Li2M x N y SO. wherein 0<x<1, 0<y<1; M and N are different and are metal elements or metalloid elements other than lithium.

[0044] In this application, the drying temperature is 105-120°C and the drying time is 8-10 hours. Within this temperature range, water can be effectively evaporated from the wet gel, which helps reduce the water content in the material and improve the stability of the material.

[0045] In this application, the heat treatment temperature is 300-500°C and the heat treatment time is 5-7 hours. Heat treatment at 300-500°C for 5-7 hours can fully volatilize the organic matter remaining in the wet gel, reduce the content of organic residues in the material, and thus improve the thermal stability of the material. Moreover, within the above heat treatment temperature and time range, it promotes grain growth, thereby improving the crystallinity of the material, which can improve the conductivity and ion conductivity of the lithium-ion battery positive electrode material, helping to improve battery performance.

[0046] In this preparation method, under the initiation of an initiator, a cross-linking agent is used to cause the free radicals of the polymerizable monomer to undergo a polymerization reaction, forming a three-dimensional network structure that is supported and dispersed in the wet gel, thereby preventing particle agglomeration, playing a role in refining the grains, and also making the grains uniformly dispersed in the wet gel; then, after heat treatment, the gelled organic matter is fully volatilized, thereby obtaining nano-sized Li2M x N ySO crystals. Through such a preparation method, the internal particle size of the antiperovskite-type positive electrode material can be made smaller and the internal particle distribution more uniform, thereby improving the cycle performance and rate performance of the lithium-ion battery.

[0047] The features and performance of the present application are further described in detail below with reference to the embodiments.

[0048] Example 1

[0049] This embodiment provides an antiperovskite cathode material Li2Fe 0.5 Mn 0.5 SO, its preparation method comprises the following steps:

[0050] (1) 2 mg of manganese acetate, 4 mg of ethyl mercaptan, and 6 mg of water were mixed and hydrolyzed at 25° C. The mixture was stirred at room temperature for 8 h using a magnetic stirrer to generate a hydrolysis product, methyl manganese disulfide.

[0051] The chemical equation for the hydrolysis reaction is: Mn(CH3COO)2+2C2H5SH+3H2O=Mn(SCH3)2+3CH3CH2OH+2O2

[0052] (2) adding nitric acid to adjust the pH value to 3, then adding 2 mg of ferric ethoxide and 4 mg of lithium ethoxide to the hydrolyzate solution of step (1), adding acrylamide as a polymerization monomer, ammonium persulfate as an initiator, and N,N-methylenebisacrylamide as a crosslinking agent to the hydrolyzate solution to generate a wet gel, and the free radicals of the polymerization monomer undergo a polymerization reaction to form a three-dimensional network structure supported and dispersed in the wet gel; wherein the amount of the polymerization monomer added is 25% of the total mass of the product solution, the amount of the initiator added is 20% of the total mass of the product solution, and the amount of the crosslinking agent added is 25% of the total mass of the product solution.

[0053] The chemical equation for the polymerization reaction is: Mn(SCH3)2+(CH3CH2O)2Fe+2CH3CH2Oli+1 / 2O2+2H2O=2Li2Fe 0.5 Mn 0.5 SO + 5CH3CH2OH

[0054] (3) The wet gel prepared in step (2) was dried at 115°C for 10 h, and then the dried product was heat treated at 400°C for 7 h to obtain nano-sized Li2Fe 0.5 Mn 0.5 SO crystal.

[0055] Example 2

[0056] This embodiment provides an antiperovskite cathode material Li2Na 0.5 Co 0.5SO, its preparation method comprises the following steps:

[0057] (1) 2 mg of sodium acetate, 4 mg of ethyl mercaptan, and 2 mg of water were mixed and hydrolyzed at 25°C. The mixture was stirred at room temperature for 8 h using a magnetic stirrer to generate a hydrolysis product, sodium dimethyldithiocarbamate.

[0058] The chemical equation for the hydrolysis reaction is: 2CH3COONa+4C2H5SH+2H2O=2(CH3)2CNS2Na+6CH3OH+N2

[0059] (2) adding nitric acid to adjust the pH value to 3, then adding 1 mg of cobalt ethoxide and 4 mg of lithium ethoxide to the hydrolyzed product solution of step (1), adding acrylamide as a polymerization monomer, ammonium persulfate as an initiator, and N,N-methylenebisacrylamide as a cross-linking agent to the hydrolyzed product solution to generate a wet gel, and the free radicals of the polymerization monomer undergo a polymerization reaction to form a three-dimensional network structure supported and dispersed in the wet gel; wherein the amount of the polymerization monomer added is 25% of the total mass of the product solution, the amount of the initiator added is 20% of the total mass of the product solution, and the amount of the cross-linking agent added is 25% of the total mass of the product solution.

[0060] The chemical equation for the polymerization reaction is: (CH3)2CNS2Na+(CH3CH2O)3Co+4CH3CH2Oli+2O2+H2O=2Li2Na 0.5 Co 0.5 SO + 7CH3CH2OH + 1 / 2N2

[0061] (3) The wet gel prepared in step (2) was dried at 115°C for 10 h, and then the dried product was heat treated at 400°C for 7 h to obtain nano-sized Li2Na 0.5 Co 0.5 SO crystal.

[0062] The remaining embodiments and comparative examples are basically the same as Example 1, except that the parameters in the preparation process are different. Please see Table 1 for details of some parameters.

[0063] Table 1

[0064]

[0065]

[0066] Test Example 1

[0067] 1. This test example tests the antiperovskite cathode material Li2Fe prepared in Example 1. 0.5 Mn 0.5 SO is used for material structure analysis, and its XRD pattern is as follows Figure 1 shown.

[0068] from Figure 1 It can be seen that the Li2Fe synthesized by this method 0.5 Mn 0.5 SO has good crystallinity and contains almost no impurities, indicating that this synthesis method can be used to synthesize Li2Fe 0.5 Mn 0.5 SO.

[0069] 2. This test example tests the antiperovskite cathode material Li2Fe prepared in Example 1. 0.5 Mn 0.5 SO was characterized by scanning electron microscopy, and its SEM image is as follows Figure 2 shown.

[0070] from Figure 2 It can be seen from the figure that the internal particle size of the sample synthesized using this method is smaller and the internal particle distribution is more uniform.

[0071] Test Example 2

[0072] In this test example, the antiperovskite positive electrode materials prepared in Examples 1-6, Comparative Examples 1 and 2 were mixed with a binder (PVDF, PVDF-HFP, PTFE, etc.) and a conductive agent (Super P, Ketjen Black, carbon nanotubes, graphene, etc.) using a traditional blade coating / spin coating method to make electrode sheets. A commercial lithium electrolyte (1M LiPF6 in EC:DEC 1:1) and a metal lithium sheet were used as the counter electrode to prepare a half-cell, and the electrochemical charge and discharge performance was tested in a charge and discharge device.

[0073] 1. First cycle discharge capacity measurement: 0.1C (1C = 230mA g -1 ) discharge capacity when discharged to the lower limit voltage.

[0074] 2. Coulombic efficiency: (first discharge capacity / first charge capacity)*100%.

[0075] 3. Place the battery in a constant temperature box at 25°C and set it at 0.1C (1C = 230mAg -1 ) current, perform constant current charge and discharge tests with a charge and discharge voltage range of 1.2-3V to observe the battery capacity attenuation and battery efficiency changes.

[0076] 4. Rate performance: The test method is to first activate at a rate of 0.05C, and then perform charge and discharge tests at 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, and 0.1C respectively.

[0077] 4. Cycle performance: The test method is to first activate at a rate of 0.05C, and then perform charge and discharge tests at 0.1C.

[0078] The test results of the above items are detailed in Table 2, where the charge and discharge curves of the battery prepared with the positive electrode material provided in Example 1 are shown in Table 2. Figure 3 As shown, the rate performance diagram of the battery prepared by the positive electrode material provided in Example 1 is as shown in Figure 4 shown.

[0079] Table 2

[0080]

[0081] From Table 2, Figure 3 and Figure 4 It can be seen that the battery prepared with the positive electrode material provided in Example 1 has a first cycle charge capacity of 366 mAh / g, a first cycle discharge capacity of 362 mAh / g, and a first cycle coulombic efficiency of 99%. Moreover, it can still maintain 0.28 Ah g at 1C. -1 The capacity is about 0.046Ah g at a rate of 5C. -1 The specific capacity is because the material prepared by the preparation method provided by the present application has a small particle size and a uniform powder distribution, which is conducive to ion transmission.

[0082] By comparing Example 1, Comparative Example 1, and Comparative Example 2, it can be seen that when the pH is 2-4, the electrochemical performance of the battery is better. Under these conditions, the hydrolysis reaction and polymerization reaction rates are balanced, the yield is high, and the grains are uniform. When the pH is lower than 2, the hydrolysis reaction rate is faster and the polymerization reaction rate is slower, resulting in incomplete polymerization. When the pH is higher than 4, the hydrolysis rate is lower and the polymerization reaction rate is faster, resulting in incomplete hydrolysis. Therefore, the electrochemical performance of the resulting battery is poor.

[0083] By comparing Examples 1, 3, and 4, it can be found that when the amount of crosslinker added is 20-30% of the total mass of the product solution, the electrochemical performance of the battery is better. When the amount of crosslinker is small (less than 20%), the degree of grain refinement will be reduced because the small amount of crosslinker cannot form a dense three-dimensional network and cannot prevent particle agglomeration. When the amount of crosslinker is large (greater than 30%), the crosslinker forms a network structure in the solution. These network structures will intersect with each other, forming more gaps and voids, making the gel structure more loose and resulting in reduced gel stability.

[0084] Comparison of Examples 1, 5, and 6 reveals that the electrochemical performance of the battery is better when the heat treatment temperature is 300-500°C. Heat treatment temperatures below 300°C can affect the decomposition of organic matter, resulting in incomplete decomposition. Heat treatment temperatures above 500°C can lead to grain growth, and excessively large grains may reduce the conductivity of the material, affecting battery performance.

[0085] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A method for preparing an antiperovskite cathode material, characterized in that: include: Mixing a metal salt containing metal M with ethanethiol and water to perform a hydrolysis reaction to obtain a product solution; Adjusting the pH of the product solution to 2-4, adding a metal salt containing metal N, lithium ethoxide, a polymerization monomer, a crosslinking agent, and an initiator to the product solution to carry out a polymerization reaction to generate a wet gel; The wet gel is dried and then heat-treated to obtain the antiperovskite cathode material Li2M x N y SO; Among them, 0<x<1, 0<y<1; The M and N are different and are metal elements or metalloid elements other than lithium; the metal salt includes carboxylates and / or alkoxides; M and N each independently include any one of Na, K, Mg, Ca, Sr, Ba, Zn, Sc, Y, Al, Ga, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Si, Sn and Sb; The polymerizable monomer includes any one of acrylamide, ethylene, propylene and acrylic acid; the crosslinking agent includes any one of N,N-methylenebisacrylamide and divinyldisiloxane; the initiator includes ammonium persulfate; The temperature of the hydrolysis reaction is 20-25°C, and the time of the hydrolysis reaction is 6-8 hours; the temperature of the polymerization reaction is 20-25°C, and the time of the polymerization reaction is 10-14 hours; the temperature of the heat treatment is 300-500°C, and the time of the heat treatment is 5-7 hours.

2. The preparation method according to claim 1, characterized in that The metal salt includes at least one of manganese acetate, sodium acetate, iron ethoxide and cobalt ethoxide.

3. The preparation method according to claim 1 or 2, characterized in that The drying temperature is 105-120° C., and the drying time is 8-10 hours.

4. The preparation method according to claim 1 or 2, characterized in that The amount of the polymerization monomer added is 20-30% of the total mass of the product solution.

5. The preparation method according to claim 1 or 2, characterized in that The added amount of the cross-linking agent is 20-30% of the total mass of the product solution.

6. The preparation method according to claim 1 or 2, characterized in that The added amount of the initiator is 20-30% of the total mass of the product solution.

7. The preparation method according to claim 1 or 2, characterized in that The particle size of the antiperovskite positive electrode material is 50-100 nm.

8. An antiperovskite cathode material, characterized in that: An antiperovskite positive electrode material prepared by the preparation method according to any one of claims 1 to 7.

9. A lithium-ion battery, characterized in that: Comprising the antiperovskite positive electrode material according to claim 8.

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