High-entropy layered oxide positive electrode material and preparation method and application thereof

Abstract

The invention discloses a high-entropy layered oxide positive electrode material and a preparation method and application thereof, and belongs to the technical field of sodium ion battery materials. The chemical formula of the positive electrode material is Na < 0.67 > M < x > Mn < y > O < 2 >. According to the invention, a plurality of functional metal elements are introduced through a multi-element co-doped high-entropy strategy, a multi-element high-entropy co-doped system containing transition metal and alkaline earth metal is constructed, and maximization of configuration entropy and minimization of Gibbs free energy are realized, so that a stable crystal framework is constructed on the thermodynamic level. A micron hollow spherical structure formed by gathering nanoscale primary crystal grains is synthesized through a simple solvothermal method, and the transmission kinetics of sodium ions is further optimized. According to the invention, the design limitation of a traditional positive electrode material is broken through, the material shows excellent electrochemical performance in the aspects of cycling stability, rate capability and the like, and an innovative solution is provided for developing a high-performance sodium ion battery positive electrode material.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium-ion battery materials, and particularly relates to a high-entropy layered oxide cathode material, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, with the continuous rise of lithium resource prices, lithium batteries are facing severe challenges in terms of resource supply, safety, and cost control. Developing a new alternative battery system has become an urgent need in the energy storage field. In this context, sodium-ion batteries are generally regarded as one of the preferred technologies for the next-generation energy storage system due to their advantages such as rich resources, low cost, environmental friendliness, good rate performance, and fast reaction kinetics.

[0003] However, the development of sodium-ion batteries still faces major challenges. Since the sodium ion radius (1.02 Å) is about 1.3 times that of the lithium ion radius (0.76 Å), its energy density and power density are relatively low, which to a certain extent restricts its commercialization process. Among them, the cathode material, as the core component of the sodium-ion battery, is the key factor determining its electrochemical performance. Among many cathode material systems, layered transition metal oxides have attracted much attention due to their high specific capacity, simple preparation process, and good structural stability. Especially manganese-based layered oxides have become a hot research direction for current sodium-ion battery cathode materials due to their high theoretical specific capacity, low toxicity, and cost advantages. However, there are still many bottlenecks in the practical application of such materials: irreversible oxygen redox reactions lead to capacity decay; significant phase changes during charge and discharge cause structural instability; the Jahn-Teller effect causes lattice distortion; Mn element dissolution results in the loss of active substances; and problems such as the formation of microcracks caused by stress accumulation seriously restrict their cycle stability and practical application value.

[0004] In order to solve the above key problems, the latest research shows that the high entropy co-doping strategy provides an innovative solution for improving the electrochemical performance of manganese-based hierarchical oxide cathode materials. High entropy materials can effectively regulate the intrinsic properties of materials by virtue of their unique multi-element synergistic effects, including high entropy effect in thermodynamics, hysteresis diffusion effect in kinetics, lattice distortion effect in structure, and "cocktail" effect in performance. Specifically, the various elements in high entropy materials occupy different positions in the lattice to form a stable crystal structure, which can effectively alleviate the structural stress and phase change problems during the electrochemical cycle. In addition, the charge compensation mechanism in high entropy cathode materials enables the positive ion and anion redox reactions to jointly provide their overall capacity, significantly improving the reversible capacity and energy density of the cathode materials. Therefore, the high entropy co-doping strategy breaks through the design limitations of traditional ternary materials, optimizes material performance through multi-atom synergistic effects, and provides new research ideas for the innovative design of sodium ion battery cathode materials. It has important scientific significance and application value for promoting the commercialization of sodium ion battery technology. Summary of the invention

[0005] In view of the above-mentioned prior art, the present invention provides a high-entropy layered oxide positive electrode material and a preparation method and application thereof, so as to solve the technical problem of poor electrical performance of sodium ion battery positive electrode materials in the prior art.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is to provide a high entropy layered oxide positive electrode material, the chemical formula of the high entropy layered oxide positive electrode material is Na 0.67 M x Mn y O2; wherein, M is Li, Mg, Co and Cu; 0.4<x<0.5, 0.7<y<0.8.

[0007] Based on the above technical solution, the present invention can also be improved as follows.

[0008] Furthermore, the chemical formula of the high entropy layered oxide cathode material is Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2.

[0009] Furthermore, the high entropy layered oxide cathode material is in the shape of a hollow sphere with a diameter of 3 to 6 μm.

[0010] The present invention also discloses a method for preparing the high entropy layered oxide positive electrode material, comprising the following steps: S1: dissolving urea in a mixed solvent of glycerol and water to obtain solution A; S2: Add the magnesium source, cobalt source, copper source, and manganese source to solution A according to the molar ratio, and stir until completely dissolved to obtain solution B; S3: Perform a hydrothermal reaction on solution B; after the reaction ends, collect the product, wash and dry it, then calcine it in an air atmosphere, and then naturally cool it to room temperature to obtain the precursor powder; S4: Dissolve the sodium source and lithium source in water according to the molar ratio, then add the precursor powder, mix evenly, and grind it under an infrared lamp until completely dry; S5: Calcinate the dried mixture in an air atmosphere, and then naturally cool it to room temperature to obtain the product.

[0011] Furthermore, the volume ratio of glycerol to water in the mixed solvent is 50 - 100:10 - 20; the material ratio of urea to the mixed solvent is 1 - 5 g:60 - 120 mL.

[0012] Furthermore, the magnesium source is at least one of magnesium chloride, magnesium carbonate, magnesium sulfate, and magnesium nitrate; the cobalt source is at least one of cobalt chloride, cobalt sulfate, and cobalt nitrate; the copper source is at least one of copper chloride, copper sulfate, and copper nitrate; the manganese source is at least one of manganese chloride, manganese nitrate, manganese sulfate, and manganese acetate.

[0013] Furthermore, in S3, the hydrothermal reaction temperature is 100 - 200 °C, and the hydrothermal reaction time is 10 - 20 h; the product washing method is to wash it 3 times with deionized water first, and then wash it 2 times with ethanol; the product drying temperature is 80 - 100 °C, and the drying time is 12 - 24 h; the calcination temperature is 400 - 600 °C, and the calcination time is 2 - 10 h.

[0014] Furthermore, the sodium source is at least one of sodium chloride, sodium hydroxide, sodium carbonate, sodium nitrate, and sodium acetate; the lithium source is at least one of lithium carbonate, lithium chloride, lithium hydroxide, lithium sulfate, lithium nitrate, and lithium acetate; the material ratio of the sodium source, lithium source, and water is 0.1 - 0.5 g:0.01 - 0.05 g:1 - 5 mL.

[0015] Furthermore, the calcination method in S5 is: first pre-calcine at 300 - 600 °C for 2 - 10 h, then raise the temperature to 700 - 1000 °C and continue to calcine for 5 - 20 h.

[0016] The present invention also discloses the application of the above high-entropy layered oxide cathode material in the preparation of sodium-ion batteries.

[0017] The beneficial effects of the present invention are: 1. The present invention breaks through the conventional design strategy of traditional single / double-element doping, and innovatively constructs a multi-element high-entropy co-doping system containing transition metals (Cu, Mn, Co) and alkaline earth metals (Mg), achieving the maximization of configurational entropy and the minimization of Gibbs free energy, thereby constructing a stable crystal framework at the thermodynamic level. The high-entropy system constructed by the present invention forms a single P2 phase through the atomic-level solid solution of five main elements (Mn, Cu, Co, Mg, Li) in the transition metal layer, fundamentally suppressing the structural degradation during the electrochemical cycle. Specifically, the present invention introduces a variety of functional metal elements, among which, Cu 2+ 、Mn 3 + and Co 3+ are electrochemically active components, jointly constructing a multi-stage redox system, which respectively contribute capacities in different voltage ranges, and synergistically improve the reversible capacity of the material; Mn 4+ and Mg 2+ as structure stabilizers can form a rigid lattice framework, which can effectively inhibit the phase transformation and lattice distortion during charge and discharge, and enhance the structural stability of the material; The introduction of Li + and Mg 2+ can trigger the reversible redox reaction of anions (O 2- / O - ), significantly broadening the voltage window of the material and additionally contributing capacity. Through the multi-element high-entropy co-doping strategy, the present invention realizes the structure-property synergistic regulation at the atomic scale, breaks through the design limitations of traditional cathode materials, and provides an innovative solution for the development of low-cost and high-energy-density cathode materials for sodium-ion batteries.

[0018] 2. The high-entropy layered oxide cathode material in the present invention has a uniform micron-sized hollow spherical morphology formed by the aggregation of nanoscale primary grains. This unique structure can provide more active sites during the cycling process, which is not only beneficial to the rapid insertion and extraction of sodium ions, but also enhances the anion redox kinetics, and significantly improves the structural stability and thermal stability of the material, effectively alleviating the stress accumulation and microcrack formation during charge and discharge.

[0019] 3. The present invention uses a solvothermal reaction to prepare the high-entropy layered oxide cathode material. The preparation method has a simple process and is easy to scale up production. The raw materials selected are common sodium sources, lithium sources, magnesium sources, cobalt sources, copper sources, and manganese sources, which are low-cost and easy to obtain. Through steps such as hydrothermal reaction and calcination, the precise regulation of the crystal structure and electronic structure of the material is achieved, ensuring the consistency and high performance of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the SEM image of the high-entropy layered oxide cathode material prepared in Example 1 of the present invention; Figure 2 TEM image of the high-entropy layered oxide cathode material prepared in Example 1 of the present invention; Figure 3 X-ray diffraction pattern of the high-entropy layered oxide cathode material prepared in Example 1 of the present invention; spectrum Figure 4 Cyclic voltammogram of the sodium-ion battery assembled with the high-entropy layered oxide in Example 1 of the present invention as the cathode material; Figure 5 Cycling performance graph of the sodium-ion batteries assembled with the cathode materials in Example 1 and Comparative Example 1 of the present invention at a small current; Figure 6 Cycling performance graph of the sodium-ion batteries assembled with the cathode materials in Example 1 and Comparative Example 1 of the present invention at a large current; Figure 7 Charge-discharge capacity-voltage graph of the sodium-ion battery assembled with the high-entropy layered oxide in Example 1 of the present invention as the cathode material. Detailed Description of the Invention

[0021] The following examples are used to illustrate the specific implementation of the present invention in detail. Examples

[0022] A high-entropy layered oxide cathode material, the chemical formula of the high-entropy layered oxide cathode material is Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2; It is prepared through the following steps: S1: Dissolve 3 g of urea in a mixed solvent of 51.5 mL of glycerol and 17.5 mL of deionized water to form a homogeneous solution A; S2: Weigh anhydrous magnesium chloride, cobalt chloride hexahydrate, copper chloride dihydrate, and manganese chloride tetrahydrate according to the molar ratio of Mg:Co:Cu:Mn = 0.13:0.08:0.08:0.71, dissolve them in solution A, and stir evenly until completely dissolved to form a homogeneous solution B; the total mass of anhydrous magnesium chloride, cobalt chloride hexahydrate, copper chloride dihydrate, and manganese chloride tetrahydrate and the feed liquid ratio of solution A is 0.01 g:1 mL; S3: Transfer solution B to a 100 mL hydrothermal reaction kettle, place it in an oven, and react at 180 °C for 12 h; after the reaction, centrifuge and wash the product, collect the bottom solid, wash it 3 times with deionized water first, and then wash it 2 times with ethanol; transfer the washed product to a vacuum drying oven and dry it at 80 °C for 12 h; then calcine the dried product in an air atmosphere at a temperature of 500 °C for 6 h, and then cool it naturally to room temperature to obtain the precursor powder; S4: Weigh sodium carbonate and lithium carbonate according to the molar ratio of Na:Li = 0.67:0.18, dissolve them in deionized water (the ratio of the total mass of sodium carbonate and lithium carbonate to the feed liquid of deionized water is 0.088:1 mL), then add the above-mentioned precursor powder, mix evenly and grind it under an infrared lamp until it is completely dry; S5: Calcinate the dried mixture in an air atmosphere. The calcination method is as follows: first, pre-calcinate it at a constant temperature of 350 °C for 2 h, then raise the temperature to 850 °C and continue to calcinate for 12 h, and then naturally cool it to room temperature and take it out to obtain the high-entropy layered oxide cathode material Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2. Example

[0023] A high-entropy layered oxide cathode material, and the chemical formula of the high-entropy layered oxide cathode material is Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2; It is prepared through the following steps: S1: Dissolve 1 g of urea in a mixed solvent of 50 mL of glycerol and 10 mL of deionized water to form a uniform solution A; S2: Weigh magnesium nitrate, cobalt nitrate, copper nitrate and manganese nitrate according to the molar ratio of Mg:Co:Cu:Mn = 0.13:0.08:0.08:0.71, dissolve them in solution A, and stir evenly until completely dissolved to form a uniform solution B; the ratio of the total mass of magnesium nitrate, cobalt nitrate, copper nitrate and manganese nitrate to the feed liquid of solution A is 0.01 g:1 mL; S3: Transfer solution B to a 100 mL hydrothermal reactor, place it in an oven, and react at 100 °C for 20 h; after the reaction, centrifuge and wash the product, collect the bottom solid, wash it 3 times with deionized water first, and then wash it 2 times with ethanol; transfer the washed product to a vacuum drying oven and dry it at 80 °C for 24 h; then calcinate the dried product in an air atmosphere at a temperature of 400 °C for 10 h, and then naturally cool it to room temperature to obtain the precursor powder; S4: Weigh sodium chloride and lithium chloride according to the molar ratio of Na:Li = 0.67:0.18, dissolve them in deionized water (the ratio of the total mass of sodium chloride and lithium chloride to the feed liquid of deionized water is 0.08:1 mL), then add the above-mentioned precursor powder, mix evenly and grind it under an infrared lamp until it is completely dry; S5: Calcinate the dried mixture in an air atmosphere. The calcination method is as follows: First, perform isothermal pre-calcination at 300 °C for 10 h, then raise the temperature to 700 °C and continue to calcinate for 20 h. Then, let it cool naturally to room temperature and take it out to obtain the high-entropy layered oxide cathode material Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2. Example

[0024] A high-entropy layered oxide cathode material, the chemical formula of the high-entropy layered oxide cathode material is Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2; It is prepared through the following steps: S1: Dissolve 5 g of urea in a mixed solvent of 100 mL of glycerol and 20 mL of deionized water to form a homogeneous solution A; S2: Weigh magnesium sulfate, cobalt sulfate, copper sulfate and manganese sulfate according to the molar ratio of Mg:Co:Cu:Mn = 0.13:0.08:0.08:0.71, dissolve them in solution A, and stir evenly until completely dissolved to form a homogeneous solution B; The total mass of magnesium sulfate, cobalt sulfate, copper sulfate and manganese sulfate and the feed liquid ratio of solution A is 0.01 g:1 mL; S3: Transfer solution B to a 100 mL hydrothermal reaction kettle, place it in an oven, and react at 200 °C for 10 h; After the reaction is completed, centrifuge and wash the product, collect the bottom solid, wash it 3 times with deionized water first, and then wash it 2 times with ethanol; Transfer the washed product to a vacuum drying oven and dry it at 100 °C for 12 h; Then calcinate the dried product in an air atmosphere at a temperature of 600 °C for 2 h, and then let it cool naturally to room temperature to obtain the precursor powder; S4: Weigh sodium nitrate and lithium nitrate according to the molar ratio of Na:Li = 0.67:0.18, dissolve them in deionized water (the total mass of sodium chloride and lithium chloride and the feed liquid ratio of deionized water is 0.08:1 mL), then add the above precursor powder, mix evenly and grind it under an infrared lamp until completely dry; S5: Calcinate the dried mixture in an air atmosphere. The calcination method is as follows: First, perform isothermal pre-calcination at 600 °C for 2 h, then raise the temperature to 1000 °C and continue to calcinate for 5 h. Then, let it cool naturally to room temperature and take it out to obtain the high-entropy layered oxide cathode material Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08Mn 0.71 O2.

[0025] Comparative Example 1 An oxide cathode material, which is the common Na 0.67 MnO2 in the prior art.

[0026] The high-entropy layered oxide cathode materials prepared in Examples 1 to 3 of the present invention have similar properties. Taking the high-entropy layered oxide cathode material in Example 1 as an example, the properties of the cathode material will be described in detail.

[0027] Experimental Example 1: Morphology Analysis of High-Entropy Layered Oxide Cathode Material Perform SEM test on Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2 in Example 1, and the results are as Figure 1 shown. It can be seen from the figure that the prepared Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2 shows a secondary particle structure formed by aggregation of fine particles into spherical shapes. The size of most individual small particles is below 1 μm, and the smaller particle size shortens the distance for sodium ions to diffuse from the inside of the particles to the surface.

[0028] Perform TEM test on Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2 in Example 1, and the results are as Figure 2 shown. It can be seen from the figure that the prepared Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2 has a uniform hollow spherical layered structure with an average diameter of 3 - 6 μm. The unique hollow spherical morphology is beneficial to the infiltration of the electrolyte, ensuring that the particles can contact the electrolyte, thereby enhancing the electrochemical reaction activity of the material.

[0029] Perform on Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71XRD analysis was performed on O2, and the results are as Figure 3 shown. As can be seen from the figure, the XRD diffraction curve shows that the prepared Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 All the diffraction peaks in the O2 sodium-ion battery cathode material can correspond well to the standard card of the P2-type structure in the hexagonal crystal system P63 / mmc space group, indicating that the material has a typical P2-phase layered structure and there are no obvious impurity peaks, indicating that the high-entropy strategy of multi-element co-doping does not damage the crystal structure of the material, but enhances its structural stability through the multi-element synergistic effect.

[0030] Experimental Example 2: Performance Analysis of High-Entropy Layered Oxide Cathode Material Based on the above high-entropy layered oxide cathode material, a high-energy-density sodium-ion secondary battery was assembled; hard carbon was used as the anode material of the sodium-ion secondary battery, and the high-entropy layered oxide cathode material was used as the cathode material of the sodium-ion secondary battery; the sodium-ion secondary battery was prepared through the following steps: (1) In a stainless-steel glove box under an inert atmosphere, the high-entropy layered oxide cathode material, conductive agent, and binder were ground and mixed according to a mass ratio of 6:2:2, and then coated on an aluminum foil current collector to make a positive electrode plate; among them, the conductive agent was acetylene black (conductive carbon black or Super P can also be used), the binder was polyacrylic acid (polytetrafluoroethylene or polyvinylidene fluoride can also be used), and the grinding time was 15 minutes; (2) In a stainless-steel glove box under an inert atmosphere, the positive electrode plate was dried at 90 °C and then cut to obtain an electrode plate, and the prepared positive electrode plate was assembled with the negative electrode plate to form a button-type sodium-ion secondary battery; among them, the electrolyte was prepared by mixing 1M NaPF6, EC / DME (v:v = 1:1) and 5% by mass of fluoroethylene carbonate, and assembled in a stainless-steel glove box with an Ar gas atmosphere where the water and oxygen contents were both less than 1 ppm using glass fiber.

[0031] Using the same method, a sodium-ion secondary battery was assembled with the cathode material in Comparative Example 1 as the cathode material of the sodium-ion secondary battery.

[0032] Cyclic voltammetry testing was performed on the sodium-ion secondary battery assembled with the high-entropy layered oxide cathode material in Example 1, and its cyclic voltammogram is as Figure 4As shown. It can be seen from the figure that the high-entropy layered oxide cathode material exhibits good reversibility during charge and discharge, with clear and symmetric redox peaks, and there is an obvious lattice oxygen oxidation peak above 4.3 V, indicating that the high-entropy strategy of multi-element co-doping effectively inhibits the Jahn-Teller effect and phase transition problems during charge and discharge, improves the reversibility of oxygen redox and contributes a certain capacity.

[0033] The cyclic performance tests of sodium-ion secondary batteries assembled with the high-entropy layered oxide cathode material in Example 1 and the oxide cathode material in Comparative Example 1 were respectively carried out at a small current, and the results are as Figure 5 shown. It can be seen from the figure that after 100 cycles at a rate of 0.5C, the capacity retention rate of the high-entropy layered oxide cathode material in Example 1 can reach more than 80%, showing excellent cyclic stability, indicating that the multi-element synergistic effect based on the high-entropy strategy effectively alleviates the structural stress and capacity decay problems of the material during cycling The cyclic performance tests of sodium-ion secondary batteries assembled with the high-entropy layered oxide cathode material in Example 1 and the oxide cathode material in Comparative Example 1 were respectively carried out at a large current, and the results are as Figure 6 shown. It can be seen from the figure that the high-entropy layered oxide cathode material in Example 1 can still maintain a high specific capacity at high rates, indicating that the unique hollow spherical structure and multi-element synergistic effect of the material optimize the sodium-ion transport kinetics and electrochemical reaction activity and significantly improve the rate performance of the material.

[0034] The charge-discharge capacity test of the sodium-ion secondary battery assembled with the high-entropy layered oxide cathode material in Example 1 was carried out in the voltage range of 1.5 - 4.5 V, and the results are as Figure 7 shown. It can be seen from the figure that the difference in the voltages corresponding to the charge-discharge curve platforms is small, indicating small polarization, and the coincidence degree of the charge-discharge curves during cycling is good, indicating good cyclic performance of the material.

[0035] In summary, the multi-element co-doping synergistic effect based on the high-entropy strategy of the present invention improves the structural stability, electrochemical reversibility and rate performance of the material. The unique micron-scale hollow spherical structure synthesized by a simple solvothermal method further optimizes the sodium-ion transport kinetics. The experimental results show that the material exhibits excellent electrochemical performance in terms of cyclic stability, rate performance, etc., providing an important technical reference for the development of high-performance sodium-ion battery cathode materials.

[0036] Although the specific implementation manners of the present invention have been described in detail in combination with the embodiments, it should not be construed as a limitation on the protection scope of this patent. Within the scope described in the claims, various modifications and deformations that can be made by those skilled in the art without creative labor still fall within the protection scope of this patent.

Claims

1. A high-entropy layered oxide cathode material, characterized in that: The chemical formula of the high-entropy layered oxide cathode material is Na 0.67 M x Mn y O2; wherein, M is Li, Mg, Co and Cu; 0.4 < x < 0.5, 0.7 < y < 0.

8.

2. The high-entropy layered oxide cathode material according to claim 1, characterized in that: The chemical formula of the high-entropy layered oxide cathode material is Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2.

3. The high-entropy layered oxide cathode material according to claim 1 or 2, characterized in that: The high-entropy layered oxide cathode material is in the shape of a hollow sphere with a diameter of 3-6 μm.

4. The preparation method of the high-entropy layered oxide cathode material according to any one of claims 1 to 3, characterized in that, The method includes the following steps: S1: Dissolve urea in a mixed solvent of glycerol and water to obtain solution A; S2: Add a magnesium source, a cobalt source, a copper source, and a manganese source to solution A according to a molar ratio, and stir until completely dissolved to obtain solution B; S3: Perform a hydrothermal reaction on solution B; after the reaction ends, collect the product, wash and dry it, then calcine it in an air atmosphere, and then naturally cool it to room temperature to obtain a precursor powder; S4: Dissolve a sodium source and a lithium source in water according to a molar ratio, then add the precursor powder, and after uniform mixing, grind it under an infrared lamp until completely dry; S5: Calcinate the dried mixture in an air atmosphere, and then naturally cool it to room temperature to obtain the product.

5. The preparation method according to claim 4, characterized in that: The volume ratio of glycerol to water in the mixed solvent is 50-100:10-20; the material ratio of urea to the mixed solvent is 1-5 g:60-120 mL.

6. The preparation method according to claim 4, characterized in that: The magnesium source is at least one of magnesium chloride, magnesium carbonate, magnesium sulfate, and magnesium nitrate; the cobalt source is at least one of cobalt chloride, cobalt sulfate, and cobalt nitrate; the copper source is at least one of copper chloride, copper sulfate, and copper nitrate; the manganese source is at least one of manganese chloride, manganese nitrate, manganese sulfate, and manganese acetate.

7. The preparation method according to claim 4, wherein: In S3, the hydrothermal reaction temperature is 100-200 °C, and the hydrothermal reaction time is 10-20 h; the product washing method is to wash it 3 times with deionized water first, and then wash it 2 times with ethanol; the product drying temperature is 80-100 °C, and the drying time is 12-24 h; the calcination temperature is 400-600 °C, and the calcination time is 2-10 h.

8. The preparation method according to claim 4, characterized in that: The sodium source is at least one of sodium chloride, sodium hydroxide, sodium carbonate, sodium nitrate, and sodium acetate; the lithium source is at least one of lithium carbonate, lithium chloride, lithium hydroxide, lithium sulfate, lithium nitrate, and lithium acetate; the material ratio of the sodium source, the lithium source, and water is 0.1-0.5 g:0.01-0.05 g:1-5 mL.

9. The preparation method according to claim 4, characterized in that, In S5, the calcination method is: first pre-calcine at 300-600 °C for 2-10 h, then raise the temperature to 700-1000 °C, and continue to calcine for 5-20 h.

10. Application of the high-entropy layered oxide cathode material according to any one of claims 1-3 in the preparation of a sodium-ion battery.

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