High-entropy layered oxide cathode material, preparation method and application thereof

Abstract

This invention discloses a high-entropy layered oxide cathode material, its preparation method, and its applications, belonging to the field of sodium-ion battery materials technology. The chemical formula of the cathode material is Na. 0.67 M x Mn y O2. This invention introduces various functionalized metal elements through a high-entropy multi-element co-doping strategy, constructing a multi-element high-entropy co-doped system containing transition metals and alkaline earth metals. This maximizes configurational entropy and minimizes Gibbs free energy, thereby constructing a stable crystal framework at the thermodynamic level. A micron-sized hollow spherical structure formed by the aggregation of nanoscale primary grains was synthesized via a simple solvothermal method, further optimizing the transport dynamics of sodium ions. This invention overcomes the design limitations of traditional cathode materials, exhibiting excellent electrochemical performance in terms of cycle stability and rate performance, providing an innovative solution for developing high-performance sodium-ion battery cathode materials.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery materials technology, specifically relating to a high-entropy layered oxide cathode material, its preparation method, and its application. Background Technology

[0002] In recent years, with the continuous rise in lithium resource prices, lithium batteries have faced severe challenges in terms of resource supply, safety, and cost control. Developing new alternative battery systems has become an urgent need in the energy storage field. Against this backdrop, sodium-ion batteries, with their advantages of abundant resources, low cost, environmental friendliness, good rate performance, and fast reaction kinetics, are widely considered one of the preferred technologies for next-generation energy storage systems.

[0003] However, the development of sodium-ion batteries still faces significant challenges. Because the radius of sodium ions (1.02 Å) is approximately 1.3 times that of lithium ions (0.76 Å), their energy and power densities are relatively low, which to some extent restricts their commercialization. Among these, the cathode material, as the core component of sodium-ion batteries, is a key factor determining their electrochemical performance. Among various cathode material systems, layered transition metal oxides have attracted considerable attention due to their high specific capacity, simple preparation process, and good structural stability. In particular, manganese-based layered oxides, due to their high theoretical specific capacity, low toxicity, and cost advantages, have become a hot research direction for sodium-ion battery cathode materials. However, these materials still face many bottlenecks in practical applications: irreversible oxygen redox reactions lead to capacity decay; significant phase transitions during charge and discharge cause structural instability; the Jahn-Teller effect causes lattice distortion; Mn element dissolution causes loss of active material; and stress accumulation leads to microcrack formation, severely restricting their cycle stability and practical application value.

[0004] To address the aforementioned key challenges, recent research has demonstrated that high-entropy co-doping strategies offer an innovative solution for enhancing the electrochemical performance of manganese-based layered oxide cathode materials. High-entropy materials, with their unique multi-element synergistic effects—including thermodynamic high-entropy, kinetic hysteresis diffusion, lattice distortion, and a "cocktail" effect—can effectively modulate the intrinsic properties of the material. Specifically, in high-entropy materials, multiple elements occupy different positions in the crystal lattice, forming a stable crystal structure that effectively alleviates structural stress and phase transition issues during electrochemical cycling. Furthermore, the charge compensation mechanism in high-entropy cathode materials allows the redox reactions of positive and anions to jointly contribute to the overall capacity, significantly improving the reversible capacity and energy density of the cathode material. Therefore, the high-entropy co-doping strategy overcomes the design limitations of traditional ternary materials, optimizing material performance through multi-atom synergistic effects. This provides new research ideas for the innovative design of sodium-ion battery cathode materials and has significant scientific 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 cathode material, its preparation method and application, so as to solve the technical problem of poor electrical performance of sodium-ion battery cathode materials in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is to provide a high-entropy layered oxide cathode material, wherein the chemical formula of the high-entropy layered oxide cathode material is Na. 0.67 M x Mn y O2; where 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 be further 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 hollow spherical with a diameter of 3~6μm.

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

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

[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; and the manganese source is at least one of manganese chloride, manganese nitrate, manganese sulfate, and manganese acetate.

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

[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; and the ratio of sodium source, lithium source, and water is 0.1~0.5g:0.01~0.05g:1~5mL.

[0015] Furthermore, the calcination method in S5 is as follows: first, pre-calcining at 300~600℃ for 2~10h, then raising the temperature to 700~1000℃ and continuing calcination for 5~20h.

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

[0017] The beneficial effects of this invention are: 1. This invention breaks through the conventional design strategy of single / dual element doping, innovatively constructing a multi-element high-entropy co-doping system containing transition metals (Cu, Mn, Co) and alkaline earth metals (Mg), maximizing configurational entropy and minimizing Gibbs free energy, thereby constructing a stable crystal framework at the thermodynamic level. The high-entropy system constructed in this invention forms a single P2 phase through atomic-level solid solution of five main elements (Mn, Cu, Co, Mg, Li) in the transition metal layer, fundamentally suppressing structural degradation during electrochemical cycling. Specifically, this invention introduces a variety of functionalized metal elements, among which Cu... 2+ Mn 3 + and Co 3+ As electrochemically active components, they jointly construct a multi-level redox system, contributing capacity in different voltage ranges and synergistically enhancing the material's reversible capacity; Mn 4+ and Mg 2+ As a structural stabilizer, Li can form a rigid lattice framework, effectively suppressing phase transitions and lattice distortions during charging and discharging, thus enhancing the structural stability of the material; + and Mg 2+ The introduction of anions (O) can trigger the reaction of anions (O) 2- / O - The reversible redox reaction significantly broadens the voltage window of the material and contributes additional capacity. This invention achieves synergistic structure-performance regulation at the atomic scale through a multi-element high-entropy co-doping strategy, breaking through the design limitations of traditional cathode materials and providing an innovative solution for developing low-cost, high-energy-density sodium-ion battery cathode materials.

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

[0019] 3. This invention employs a solvothermal reaction to prepare high-entropy layered oxide cathode materials. The preparation method is simple and easy to scale up. Commonly used raw materials such as sodium, lithium, magnesium, cobalt, copper, and manganese are selected, which are inexpensive and readily available. Through hydrothermal reaction and calcination steps, precise control of the material's crystal structure and electronic structure is achieved, ensuring product consistency and high performance. Attached Figure Description

[0020] Figure 1 This is a SEM image of the high-entropy layered oxide cathode material prepared in Example 1 of the present invention; Figure 2 This is a TEM image of the high-entropy layered oxide cathode material prepared in Example 1 of the present invention; Figure 3 The X-ray diffraction pattern of the high-entropy layered oxide cathode material prepared in Example 1 of this invention; spectrum. Figure 4 The figure shows the cyclic voltammetry curve of a sodium-ion battery assembled using the high-entropy layered oxide as the positive electrode material in Example 1 of this invention. Figure 5 The graph shows the cycle performance of sodium-ion batteries assembled with the cathode materials in Example 1 and Comparative Example 1 of this invention under low current. Figure 6 The graph shows the cycling performance of sodium-ion batteries assembled with the cathode materials in Example 1 and Comparative Example 1 of this invention under high current. Figure 7 The charge / discharge capacity-voltage diagram shows the sodium-ion battery assembled using the high-entropy layered oxide as the positive electrode material in Example 1 of this invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in detail below with reference to examples. Example

[0022] A high-entropy layered oxide cathode material, the chemical formula of which is Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2 is obtained through the following steps: S1: Dissolve 3g of urea in a mixed solvent of 51.5mL glycerol and 17.5mL 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 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 to the material-liquid ratio of solution A is 0.01g:1mL; S3: Transfer solution B to a 100mL hydrothermal reactor, place it in an oven, and react at 180℃ for 12h. After the reaction, centrifuge and wash the product, collect the bottom solid, wash it 3 times with deionized water, and then wash it 2 times with ethanol. Transfer the washed product to a vacuum drying oven and dry it at 80℃ for 12h. Then calcine the dried product at 500℃ for 6h in air atmosphere, 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 Na:Li=0.67:0.18, dissolve them in deionized water (the total mass of sodium carbonate and lithium carbonate to the deionized water is 0.088:1mL), then add the above precursor powder, mix evenly, and grind under an infrared lamp until completely dry. S5: The dried mixture was calcined in air. The calcination method was as follows: first, pre-calcination was carried out at a constant temperature of 350℃ for 2 hours, then the temperature was increased to 850℃ and calcined for another 12 hours. After cooling naturally to room temperature, the mixture was removed 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, the chemical formula of which is Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2 is obtained through the following steps: S1: Dissolve 1g of urea in a mixed solvent of 50mL glycerol and 10mL deionized water to form a homogeneous solution A; S2: Weigh magnesium nitrate, cobalt nitrate, copper nitrate, and manganese nitrate according to the molar ratio 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 nitrate, cobalt nitrate, copper nitrate, and manganese nitrate to the material-liquid ratio of solution A is 0.01 g: 1 mL; S3: Transfer solution B to a 100mL hydrothermal reactor, place it in an oven, and react at 100℃ for 20h. After the reaction, centrifuge and wash the product, collect the bottom solid, wash it three times with deionized water, and then wash it twice with ethanol. Transfer the washed product to a vacuum drying oven and dry it at 80℃ for 24h. Then calcine the dried product at 400℃ for 10h in air atmosphere, and then cool it naturally to room temperature to obtain the precursor powder. S4: Weigh sodium chloride and lithium chloride according to the molar ratio Na:Li=0.67:0.18, dissolve them in deionized water (the total mass of sodium chloride and lithium chloride to the deionized water is 0.08:1mL), then add the above precursor powder, mix evenly, and grind under an infrared lamp until completely dry. S5: The dried mixture was calcined in air. The calcination method was as follows: first, pre-calcination was carried out at a constant temperature of 300℃ for 10 hours, then the temperature was increased to 700℃ and calcined for another 20 hours. After that, it was naturally cooled to room temperature and removed 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 which is Na 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2 is obtained through the following steps: S1: Dissolve 5g of urea in a mixed solvent of 100mL of glycerol and 20mL 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 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 to the material-liquid ratio of solution A is 0.01 g: 1 mL; S3: Transfer solution B to a 100mL hydrothermal reactor, place it in an oven, and react at 200℃ for 10h; after the reaction, centrifuge and wash the product, collect the bottom solid, wash it 3 times with deionized water, and then wash it 2 times with ethanol; transfer the washed product to a vacuum drying oven and dry it at 100℃ for 12h; then calcine the dried product at 600℃ for 2h in air atmosphere, and then cool it naturally to room temperature to obtain the precursor powder; S4: Weigh sodium nitrate and lithium nitrate according to the molar ratio Na:Li=0.67:0.18, dissolve them in deionized water (the total mass of sodium chloride and lithium chloride to the deionized water is 0.08:1mL), then add the above precursor powder, mix evenly, and grind under an infrared lamp until completely dry. S5: The dried mixture was calcined in air. The calcination method was as follows: first, it was pre-calcined at a constant temperature of 600℃ for 2 hours, then the temperature was increased to 1000℃ and calcined for another 5 hours. After that, it was naturally cooled to room temperature and removed 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, wherein the oxide cathode material is Na, which is commonly used in the prior art. 0.67 MnO2.

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

[0027] Experimental Example 1: Morphology Analysis of High-Entropy Layered Oxide Cathode Materials Na in Example 1 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2 was subjected to SEM testing, and the results were as follows: Figure 1 As shown in the figure. 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 exhibits a secondary particle structure consisting of fine particles agglomerated into spherical shapes. The size of most individual particles is less than 1 μm, and the smaller particle size shortens the distance that sodium ions inside the particles diffuse to the surface.

[0028] For Na in Example 1 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2 was subjected to TEM testing, and the results were as follows: Figure 2 As shown in the figure. 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 3~6μm. The unique hollow spherical morphology is conducive to the wetting of electrolyte, ensuring that the particles can contact the electrolyte, thereby improving the electrochemical reactivity of the material.

[0029] For Na in Example 1 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 follows: Figure 3 As shown in the figure, the XRD diffraction curves reveal 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 correspond well to the standard card of the P2 type structure of the hexagonal crystal system P63 / mmc space group, indicating that the material has a typical P2 phase layered structure. The absence of obvious impurity peaks indicates that the high-entropy strategy of multi-element co-doping has not destroyed the crystal structure of the material, but has instead enhanced its structural stability through the synergistic effect of multi-element doping.

[0030] Experimental Example 2: Performance Analysis of High-Entropy Layered Oxide Cathode Materials Based on the aforementioned high-entropy layered oxide cathode material, a high-energy-density sodium-ion secondary battery is assembled; hard carbon is used as the negative electrode material for the sodium-ion secondary battery, and the high-entropy layered oxide cathode material is used as the positive electrode material; the sodium-ion secondary battery is prepared through the following steps: (1) In a stainless steel glove box under an inert atmosphere, the high-entropy layered oxide positive electrode material is ground and mixed with a conductive agent and a binder in a mass ratio of 6:2:2, and then coated onto an aluminum foil current collector to form a positive electrode sheet; wherein, the conductive agent is acetylene black (or conductive carbon black or Super P), the binder is polyacrylic acid (or polytetrafluoroethylene or polyvinylidene fluoride), and the grinding time is 15 minutes. (2) In a stainless steel glove box under an inert atmosphere, the positive electrode sheet is dried at 90°C and then cut to obtain an electrode sheet. The prepared positive electrode sheet and negative electrode sheet are matched and assembled into a button sodium-ion secondary battery. The electrolyte is prepared by mixing 1M NaPF6, EC / DME (v:v=1:1) and 5% fluoroethylene carbonate. The battery is assembled with glass fiber in an Ar atmosphere stainless steel glove box with water and oxygen content of less than 1ppm.

[0031] Using the same method, sodium-ion secondary batteries were assembled using the positive electrode material from Comparative Example 1 as the positive electrode material.

[0032] Cyclic voltammetry tests were performed on the sodium-ion secondary battery assembled using the high-entropy layered oxide cathode material described in Example 1, and the cyclic voltammetry curves are shown below. Figure 4As shown in the figure, the high-entropy layered oxide cathode material exhibits good reversibility during charge and discharge, with clear and symmetrical redox peaks. Furthermore, a significant lattice oxygen oxidation peak exists above 4.3V, indicating that the high-entropy strategy of multi-element co-doping effectively suppresses the Jahn-Teller effect and phase transition during charge and discharge, improves the reversibility of oxygen redox, and contributes to a certain capacity.

[0033] The sodium-ion secondary batteries assembled with the high-entropy layered oxide cathode material of Example 1 and the oxide cathode material of Comparative Example 1 were subjected to cycle performance tests at low currents, and the results are as follows. Figure 5 As shown in the figure, the high-entropy layered oxide cathode material in Example 1 retains over 80% of its capacity after 100 cycles at 0.5C, demonstrating excellent cycle stability. This indicates 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 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 subjected to high-current cycle performance tests, and the results are as follows: Figure 6 As shown in the figure, the high-entropy layered oxide cathode material in Example 1 can maintain a high specific capacity even at high rates, indicating that the material's unique hollow spherical structure and multi-element synergistic effect optimize sodium ion transport kinetics and electrochemical reaction activity, and significantly improve the material's rate performance.

[0034] The sodium-ion secondary battery assembled using the high-entropy layered oxide cathode material in Example 1 was subjected to charge-discharge capacity tests within a voltage range of 1.5-4.5V. The results are as follows: Figure 7 As shown in the figure, the voltage difference corresponding to the plateau of the charge-discharge curve is small, indicating small polarization. The charge-discharge curves overlap well during cycling, indicating good cycling performance of the material.

[0035] In summary, this invention leverages the synergistic effect of multi-element co-doping based on a high-entropy strategy to enhance the material's structural stability, electrochemical reversibility, and rate performance. The unique micron-sized hollow spherical structure synthesized via a simple solvothermal method further optimizes sodium ion transport kinetics. Experimental results demonstrate that this material exhibits excellent electrochemical performance in terms of cycle stability and rate performance, providing important technical reference for the development of high-performance sodium-ion battery cathode materials.

[0036] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A high-entropy layered oxide cathode material, characterized in that: The high-entropy layered oxide cathode material is hollow spherical with a diameter of 3-6 μm; its chemical formula is Na. 0.67 Li 0.18 Mg 0.13 Co 0.08 Cu 0.08 Mn 0.71 O2.

2. The method for preparing the high-entropy layered oxide cathode material according to claim 1, characterized in that, Includes the following steps: S1: Dissolve urea in a mixed solvent of glycerol and water to obtain solution A; S2: Add magnesium source, cobalt source, copper source and manganese source to solution A according to the molar ratio, stir until completely dissolved to obtain solution B; S3: Perform a hydrothermal reaction on solution B; after the reaction is complete, collect the product, wash and dry it, then calcine it in air and cool it naturally to room temperature to obtain the precursor powder. S4: Dissolve sodium source and lithium source in water according to the molar ratio, then add precursor powder, mix evenly, and grind under infrared lamp until completely dry; S5: Calcine the dried mixture in air atmosphere, and then let it cool naturally to room temperature to obtain the final product.

3. The preparation method according to claim 2, characterized in that: The volume ratio of glycerol to water in the mixed solvent is 50~100:10~20; the material-to-liquid ratio of urea to the mixed solvent is 1~5g:60~120mL.

4. The preparation method according to claim 2, 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; and the manganese source is at least one of manganese chloride, manganese nitrate, manganese sulfate, and manganese acetate.

5. The preparation method according to claim 2, characterized in that: The hydrothermal reaction temperature in S3 is 100~200℃, and the hydrothermal reaction time is 10~20h; the product is washed 3 times with deionized water and then 2 times with ethanol; the product is dried at 80~100℃ for 12~24h; and the calcination temperature is 400~600℃ for 2~10h.

6. The preparation method according to claim 2, 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 ratio of sodium source, lithium source, and water is 0.1~0.5g:0.01~0.05g:1~5mL.

7. The preparation method according to claim 2, characterized in that, The calcination method in S5 is as follows: first, pre-calcinate at 300~600℃ for 2~10h, then raise the temperature to 700~1000℃ and continue calcining for 5~20h.

8. The application of the high-entropy layered oxide cathode material according to claim 1 in the preparation of sodium-ion batteries.

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