High-entropy metal oxide positive electrode material and preparation method therefor, and sodium-ion battery

Abstract

A high-entropy metal oxide positive electrode material and a preparation method therefor, and a sodium-ion battery. The chemical formula of the high-entropy metal oxide positive electrode material is NaxNiaFebMncM1dM2eM3fM4gO2, wherein 0.8≤x≤1.05, 0.1≤a≤0.2, 0.1≤b≤0.2, 0.1≤c≤0.2, 0≤d≤0.25, 0≤e≤0.25, 0≤f≤0.25, and 0≤g≤0.25; d, e, f, and g cannot be 0 at the same time; a+b+c+d+e+f+g=1; and M1, M2, M3, and M4 are each independently selected from Li, Mg, Cu, Zn, Ca, V, Al, or Zr. A plurality of specific types of low-cost metal elements are introduced into the layered oxide positive electrode material by using a high-entropy strategy; therefore, the structure of the O3-type material can be stabilized, and the stability of the material during a cycling process is improved.

Description

High-entropy metal oxide positive electrode material, preparation method thereof and sodium ion battery TECHNICAL FIELD

[0001] The application belongs to the technical field of positive electrode materials, and particularly relates to a high-entropy metal oxide positive electrode material, a preparation method thereof and a sodium ion battery. BACKGROUND

[0002] As a promising energy storage device to replace lithium ion batteries, sodium ion batteries have received extensive attention in recent years, especially in the case of potential shortage of lithium resources. The abundance of sodium in the earth's crust is much higher than that of lithium, which makes sodium ion batteries have potential advantages in production cost, sustainability and environmental friendliness. In recent years, developing high-performance and low-cost sodium ion battery positive electrode materials is a research hotspot in the field of current energy storage technology, which is expected to occupy an important position in the future energy storage market. Among them, layered transition metal oxide positive electrode materials are considered as one of the most promising positive electrode materials in sodium ion batteries due to their high energy density and low cost.

[0003] The structural general formula of the layered transition metal oxide positive electrode material is Na x TM02, wherein TM represents a transition metal element, for example, including Fe, Mn, Ni or Co, etc., which is similar in structure to the ternary positive electrode material of lithium ion batteries. In addition, layered oxides can be divided into O3 and P2 two configurations, wherein the O3 structure has a higher initial sodium content and capacity, and the P2 structure has a larger sodium interlayer spacing, which is beneficial to the rapid transmission of sodium ions and structural stability.

[0004] However, the layered transition metal oxide positive electrode material faces many challenges in the process of practical application, including poor air stability, interface side reaction and complex phase change in the charging and discharging process. In order to improve the comprehensive performance of the layered transition metal oxide positive electrode material, researchers have adopted various modification strategies, such as chemical element substitution, surface and interface modification and structure regulation, in order to improve its air stability, reduce interface side reaction and inhibit phase change. The preparation method of the layered transition metal oxide positive electrode material disclosed in the related art is to mix transition metal source, oxidizing agent and sodium source and then sinter at high temperature to obtain the layered transition metal oxide positive electrode material. However, the solid phase mixing method cannot guarantee the complete mixing of multiple metal elements, and the reaction is easy to be incomplete. In addition, the particle size of the transition metal oxide raw material used must be nanoscale, which makes the cost of the preparation raw material higher.

[0005] Therefore, in the art, there is an urgent need to develop a layered transition metal oxide positive electrode material with stable structure and low cost and a preparation method thereof to solve the above problems.

[0006] SUMMARY

[0007] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0008] The application provides a high-entropy metal oxide positive electrode material, a preparation method thereof and a sodium ion battery. The application introduces multiple specific low-cost metal elements into a layered oxide positive electrode material by using a high-entropy strategy, which can stabilize the stability of the O3-type material structure and further improve the stability in the cycle process.

[0009] In a first aspect, the application provides a high-entropy metal oxide positive electrode material, the chemical formula of the high-entropy metal oxide positive electrode material is Na x Ni a Fe b Mn c M1 d M2 e M3 f M4 g O2, wherein 0.8≤x≤1.05, 0.1≤a≤0.2, 0.1≤b≤0.2, 0.1≤c≤0.2, 0≤d≤0.25, 0≤e≤0.25, 0≤f≤0.25, 0≤g≤0.25; d, e, f, g cannot be 0 at the same time; and a+b+c+d+e+f+g=1; M1, M2, M3, and M4 are each independently selected from Li, Mg, Cu, Zn, Ca, V, Al, or Zr.

[0010] Firstly, the application can inhibit the phase change process in the electrochemical process by introducing multiple different types of metal elements into the layered metal oxide positive electrode material, thereby enhancing the stability of the O3-type material structure and improving the stability of the assembled sodium ion battery in the cycle process; secondly, due to the disordered distribution of multiple ions in the high-entropy metal oxide positive electrode material provided by the application, the migration energy barrier of sodium ions can be reduced, the diffusion coefficient of sodium ions can be improved, and the rate performance of the battery can be enhanced; in addition, different transition metal ions in the high-entropy metal oxide positive electrode material provided by the application can provide different redox reactions, thereby increasing the total capacity of the layered metal oxide positive electrode material; finally, the content of the high-cost nickel metal element is diluted to a certain extent by introducing other types of metal elements, thereby further reducing the production cost and achieving a balance between the high capacity density and the low production cost of the positive electrode material.

[0011] In one embodiment, the chemical formula of the high-entropy metal oxide positive electrode material is NaNi 0.1 Mg 0.05 Cu 0.25 Fe 0.2 Mn 0.2 Zn 0.1 Ca0.1 O2.

[0012] In an embodiment, the particle size of the high-entropy metal oxide positive electrode material is in the range of 0.1-8 μm, for example, 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc. The high-entropy metal oxide positive electrode material product obtained by mixing different particle sizes can improve the compaction density of the positive electrode material.

[0013] In the present application, by adjusting the particle size range of the high-entropy metal oxide positive electrode material, the positive electrode material exhibits different sodium ion deintercalation rates, thereby exhibiting different rate performance.

[0014] In a second aspect, the present application provides a method for preparing the high-entropy metal oxide positive electrode material according to the first aspect, the method comprising the following steps:

[0015] Mixing at least one of M1 source, M2 source, M3 source and M4 source, nickel source, iron source, manganese source and solvent according to the formula amount to obtain a mixed solution;

[0016] Spray pyrolysis of the mixed solution to obtain an oxide composite precursor material;

[0017] Calcining the oxide composite precursor material and sodium source to obtain the high-entropy metal oxide positive electrode material.

[0018] In an embodiment, the M1 source, M2 source, M3 source and M4 source are each independently selected from lithium source, magnesium source, copper source, zinc source, calcium source, vanadium source, aluminum source or zirconium source.

[0019] Optionally, the lithium source includes lithium chloride.

[0020] Optionally, the magnesium source includes magnesium chloride or magnesium sulfate, and is optionally magnesium chloride.

[0021] Optionally, the copper source includes copper chloride or copper sulfate, and is optionally copper chloride.

[0022] Optionally, the zinc source includes zinc chloride or zinc sulfate, and is optionally zinc chloride.

[0023] Optionally, the calcium source includes calcium chloride or calcium sulfate, and is optionally calcium chloride.

[0024] Optionally, the vanadium source includes vanadium chloride.

[0025] Optionally, the aluminum source includes aluminum chloride.

[0026] Optionally, the zirconium source includes zirconium chloride.

[0027] Optionally, the nickel source comprises nickel chloride or nickel sulfate, and is optionally nickel chloride.

[0028] Optionally, the iron source comprises iron chloride or iron sulfate, and is optionally iron chloride.

[0029] Optionally, the manganese source comprises manganese chloride or manganese sulfate, and is optionally manganese chloride.

[0030] Optionally, the solvent comprises water.

[0031] In one embodiment, the total concentration of the combination of all metal ions in the mixed solution is 1-3 mol / L, for example, it can be 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, 2.8 mol / L, 3 mol / L, etc. The present application further adjusts the particle size range of the prepared high-entropy metal oxide positive electrode material by regulating the concentration of the combination of all metal elements in the mixed solution before spraying.

[0032] In one embodiment, the temperature of spraying in the spray pyrolysis is 200-240°C, for example, it can be 200°C, 210°C, 220°C, 230°C, 240°C, etc.

[0033] Optionally, the pyrolysis in the spray pyrolysis is carried out under sintering.

[0034] Optionally, the temperature of sintering is 630-670°C, for example, it can be 630°C, 640°C, 650°C, 660°C, 670°C, etc., and the time is 3-5 h, for example, it can be 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc.

[0035] In the present application, by regulating the temperature of spraying and sintering in the spray pyrolysis, the high-entropy metal oxide positive electrode material can be fully crystallized. If the sintering temperature is too low, the positive electrode material crystal will not be fully crystallized, resulting in more defects in the crystal, which is not conducive to capacity development, and the structure stability of the material is poor. On the contrary, it will make the crystal particles grow too large, thereby affecting the repeated deintercalation of sodium ions, resulting in a low capacity of the positive electrode material.

[0036] In one embodiment, the molar ratio of the combination of all metal elements in the oxide composite precursor material to the sodium element in the sodium source is 1:1.

[0037] Optionally, the sodium source comprises sodium carbonate.

[0038] In one embodiment, the temperature of the calcination is 830-950℃, for example, it can be 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 900℃, 910℃, 920℃, 950℃, etc., and the time is 9-11h, for example, it can be 9h, 10h, 11h, etc.

[0039] In the present application, by using the chlorides of a plurality of different metal elements with low cost to carry out spray pyrolysis, an oxide composite precursor material is obtained, and then it is mixed with a sodium source for calcination, so as to obtain a high-entropy metal oxide positive electrode material. Compared with the method of mixing and calcining oxides of a plurality of transition metal elements disclosed in the related art, the preparation method of the high-entropy metal oxide positive electrode material has the advantages of low cost of raw materials, uniform mixing of different metal elements, and simple process flow, and the prepared high-entropy metal oxide positive electrode material exhibits excellent sodium ion deintercalation capacity and cycle stability.

[0040] In a third aspect, the present application provides a sodium ion battery, which comprises a positive electrode, a negative electrode, an electrolyte and a separator, and the positive electrode comprises the high-entropy metal oxide positive electrode material according to the first aspect.

[0041] Compared with the related art, the present application has the following beneficial effects:

[0042] The present application provides a high-entropy metal oxide positive electrode material. On the one hand, first, the present application introduces a plurality of different types of metal elements into the layered metal oxide positive electrode material, which can inhibit the phase change process in the electrochemical process, thereby enhancing the stability of the O3-type material structure and improving the cycle stability of the assembled sodium ion battery. Second, due to the disordered distribution of a plurality of ions in the high-entropy metal oxide positive electrode material provided by the present application, the migration energy barrier of sodium ions can be reduced, and the diffusion coefficient of sodium ions can be improved, thereby enhancing the rate performance of the battery. In addition, different transition metal ions in the high-entropy metal oxide positive electrode material provided by the present application can provide different redox reactions, thereby increasing the total capacity of the layered metal oxide positive electrode material. Finally, the introduction of other types of metal elements in the present application dilutes the content of high-cost nickel metal elements to some extent, thereby further reducing the production cost and achieving a balance between high capacity density and low production cost of the positive electrode material.

[0043] On the other hand, the present application adopts a spray pyrolysis synthesis route with low cost and simple process flow, obtains an oxide composite precursor material of a plurality of metal elements by spray pyrolysis, and then mixes it with a sodium source for calcination, so as to finally obtain a corresponding high-entropy metal oxide positive electrode material, thereby improving the uniformity of mixing of different metal elements and the process yield.

[0044] Other aspects can become apparent from a review of the drawings and detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0045] The accompanying drawings are included to provide a further understanding of the technical solutions of the present application, constitute a part of the specification and are used to explain the technical solutions of the present application together with the embodiments of the present application, but do not constitute a limitation on the technical solutions of the present application.

[0046] FIG. 1 is a scanning electron microscope image of the NaNi 0.1 Mg 0.05 Cu 0.25 Fe 0.2 Mn 0.2 Zn 0.1 Ca 0.1 A scanning electron microscope image of the O2 positive electrode material, with a scale of 5 μm;

[0047] FIG. 2 is a scanning electron microscope image of the NaNi 0.1 Mg 0.05 Cu 0.25 Fe 0.2 Mn 0.2 Zn 0.1 Ca 0.1 A cycle performance diagram of a sodium ion battery assembled from the O2 positive electrode material. DETAILED DESCRIPTION

[0048] The technical solutions of the present application will be further described below by combining the drawings and the specific embodiments. It should be understood by those skilled in the art that the embodiments are only used to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0049] Embodiment 1

[0050] The present embodiment provides a high-entropy metal oxide positive electrode material, and the chemical formula of the high-entropy metal oxide positive electrode material is NaNi 0.1 Mg 0.05 Cu 0.25 Fe 0.2 Mn 0.2 Zn 0.1 Ca 0.1 O2, with a particle size range of 1-5 μm, as shown in FIG. 1.

[0051] The present embodiment also provides a preparation method of the above high-entropy metal oxide positive electrode material, which comprises the following steps:

[0052] chloride, manganese chloride, zinc chloride and calcium chloride are fully mixed with water in a proportion of 1:0.5:2.5:2:2:1:1 of element molar ratio of nickel element, magnesium element, copper element, iron element, manganese element, zinc element and calcium element, and a mixed solution is obtained after complete dissolution, wherein the concentration of the combination of nickel ion, magnesium ion, copper ion, iron ion, manganese ion, zinc ion and calcium ion in the mixed solution is 1 mol / L;

[0053] The mixed solution is subjected to spray pyrolysis, the temperature of spraying is 220℃, the material sprayed out directly reaches a pyrolysis furnace for sintering, the temperature of sintering is set to 650℃, and the sintering time is 4h, to obtain an oxide composite precursor material;

[0054] The oxide composite precursor material and sodium carbonate are fully mixed and then subjected to calcination treatment in a muffle furnace, wherein the molar ratio of the combination of all metal elements in the oxide composite precursor material and sodium element in the sodium carbonate is 1:1; the temperature of calcination is 950℃, the calcination time is 10h, and the high-entropy metal oxide positive electrode material is obtained.

[0055] Example 2

[0056] The embodiment provides a high-entropy metal oxide positive electrode material, and the chemical formula of the high-entropy metal oxide positive electrode material is NaNi 0.1 Mg 0.05 Cu 0.25 Fe 0.2 Mn 0.2 Zn 0.1 Ca 0.1 O2, and the particle size range is 2-6μm.

[0057] The embodiment also provides a preparation method of the high-entropy metal oxide positive electrode material, and the preparation method comprises the following steps:

[0058] chloride, manganese chloride, zinc chloride and calcium chloride are fully mixed with water in a proportion of 1:0.5:2.5:2:2:1:1 of element molar ratio of nickel element, magnesium element, copper element, iron element, manganese element, zinc element and calcium element, and a mixed solution is obtained after complete dissolution, wherein the concentration of the combination of nickel ion, magnesium ion, copper ion, iron ion, manganese ion, zinc ion and calcium ion in the mixed solution is 1 mol / L;

[0059] The mixed solution is subjected to spray pyrolysis, the temperature of spraying is 220℃, the material sprayed out directly reaches a pyrolysis furnace for sintering, the temperature of sintering is set to 650℃, and the sintering time is 4h, to obtain an oxide composite precursor material;

[0060] The oxide composite precursor material and sodium carbonate are mixed thoroughly and then calcined in a muffle furnace, wherein the molar ratio of the combination of all metal elements in the oxide composite precursor material and the sodium element in the sodium carbonate is 1:1; the calcination temperature is 950°C, and the calcination time is 10h, to obtain the high-entropy metal oxide positive electrode material.

[0061] Example 3

[0062] The present embodiment provides a high-entropy metal oxide positive electrode material, which has a chemical formula of NaNi 0.1 Mg 0.05 Cu 0.25 Fe 0.2 Mn 0.2 Zn 0.1 Ca 0.1 O2, and the particle size range is 3-8μm.

[0063] The present embodiment also provides a preparation method of the high-entropy metal oxide positive electrode material, which comprises the following steps:

[0064] Nickel chloride, magnesium chloride, copper chloride, iron chloride, manganese chloride, zinc chloride and calcium chloride are mixed with water in a proportion of 1:0.5:2.5:2:2:1:1 of the element molar ratio of nickel element, magnesium element, copper element, iron element, manganese element, zinc element and calcium element, and a mixed solution is obtained after complete dissolution, wherein the concentration of the combination of nickel ions, magnesium ions, copper ions, iron ions, manganese ions, zinc ions and calcium ions in the mixed solution is 3mol / L;

[0065] The mixed solution is subjected to spray pyrolysis at a temperature of 220°C, and the material sprayed out is directly sent to a pyrolysis furnace for sintering, wherein the sintering temperature is set to 650°C, and the sintering time is 4h, to obtain an oxide composite precursor material;

[0066] The oxide composite precursor material and sodium carbonate are mixed thoroughly and then calcined in a muffle furnace, wherein the molar ratio of the combination of all metal elements in the oxide composite precursor material and the sodium element in the sodium carbonate is 1:1; the calcination temperature is 950°C, and the calcination time is 10h, to obtain the high-entropy metal oxide positive electrode material.

[0067] Example 4

[0068] The difference between the present embodiment and Example 1 is that the sintering temperature in the spray pyrolysis is 600°C, and the other conditions are the same as those in Example 1.

[0069] Example 5

[0070] The embodiment differs from example 1 in that the sintering temperature in the spray pyrolysis is 700℃, and the others are the same as example 1.

[0071] Comparative example 1

[0072] The present comparative example provides a preparation method of solid phase mixing calcination, which comprises the following steps:

[0073] The metal atoms in the chemical formula are weighed respectively NiO, CuO, Fe2O3, MnO, ZnO and CaO powders, and uniformly mixed. The above materials and sodium carbonate are prepared according to the molar ratio of 1:1.02, put into a ball mill tank, add zirconia balls, the mass ratio of zirconia balls and raw materials is 10:1, the dispersing agent is anhydrous ethanol, the ball milling speed is 400r / min, and the ball milling time is 6h, so as to ensure that the raw materials are fully mixed and refined. The mixture after ball milling is dried at 60℃ to prepare a precursor. The precursor is calcined in an air atmosphere, the calcination temperature is 950℃, and the calcination time is 10h. The calcined sample is ground in a mortar and sieved.

[0074] Comparative example 2

[0075] The present comparative example provides a positive electrode material, the chemical formula is NaNi 0.1 Cu 0.3 Fe 0.2 Mn 0.2 Zn 0.1 Ca 0.1 O2.

[0076] Comparative example 3

[0077] The present comparative example provides a positive electrode material, the chemical formula is NaNi 0.1 Mg 0.05 Cu 0.25 Fe 0.2 Mn 0.2 Zn 0.2 O2.

[0078] Comparative example 4

[0079] The present comparative example provides a positive electrode material, the chemical formula is NaNi

[0080] Test conditions

[0081] The oxide positive electrode materials provided by examples 1 to 5 and comparative examples 1 to 4 are tested, and the test method is as follows:

[0082] The sodium ion battery positive electrode materials obtained by the above examples and comparative examples are prepared into positive electrode sheets, and then prepared into sodium ion batteries with sodium sheets.

[0083] Cycle performance test:

[0084] The battery was first charged at a constant current of 0.1C to a voltage of 4.0V, charged at a constant voltage to a current of 0.05V, and then discharged at a constant current of 0.1C to a voltage of 2.0V at a temperature of 25°C. The voltage test range of 2.0-4.0V was maintained, and then the second and third cycles of charge-discharge cycles were carried out at a rate of 0.2C and 0.5C, respectively, which was the activation process of the battery. Then, the charge-discharge cycle was carried out at a rate of 1C for 50 cycles to observe the cycle stability.

[0085] The test results are shown in Table 1:

[0086] Table 1

[0087] As can be seen from Table 1, by introducing multiple different types of metal elements into the layered metal oxide positive electrode material, the capacity and structural stability of the O3-type material are enhanced, and ultimately the stability and specific capacity of the assembled sodium ion battery are improved. As can be seen from Figure 2, the high-entropy metal oxide positive electrode material provided in Example 1 has a high discharge specific capacity and good cycle performance.

[0088] As can be seen from the comparison of Example 1, Example 4-5, by adjusting the sintering temperature in the spray pyrolysis, the high-entropy metal oxide positive electrode material can be fully crystallized, thereby improving its capacity.

[0089] As can be seen from the comparison of Example 1 and Comparative Example 1, compared with the method of mixing and calcining oxides of multiple transition metal elements disclosed in the related art, the preparation method of the high-entropy metal oxide positive electrode material provided in the present application has the advantages of low raw material cost, uniform mixing of different metal elements, and simple process flow, and the prepared high-entropy metal oxide positive electrode material exhibits excellent sodium ion deintercalation capacity and cycle stability.

[0090] As can be seen from the comparison of Example 1 and Comparative Examples 2-4, conventional single-element doping or lack of doping of a certain element makes the comprehensive performance of the sodium ion battery assembled from the prepared high-entropy metal oxide positive electrode material worse.

[0091] The applicant declares that the above examples are used to illustrate the process method of the present application, but the present application is not limited to the above process steps, i.e. it does not mean that the present application must rely on the above process steps to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the raw materials selected by the present application, addition of auxiliary ingredients, selection of specific methods, etc. fall within the scope of protection and disclosure of the present application.

Claims

1. A high-entropy metal oxide cathode material, wherein, The chemical formula of the high-entropy metal oxide cathode material is Na. x Ni a Fe b Mn c M1 d M2 e M3 f M4 g O2, where 0.8≤x≤1.05, 0.1≤a≤0.2, 0.1≤b≤0.2, 0.1≤c≤0.2, 0≤d≤0.25, 0≤e≤0.25, 0≤f≤0.25, 0≤g≤0.25; d, e, f, g cannot all be 0; and a+b+c+d+e+f+g=1; M1, M2, M3, and M4 are each independently selected from Li, Mg, Cu, Zn, Ca, V, Al, or Zr.

2. The high-entropy metal oxide cathode material according to claim 1, wherein, The chemical formula of the high-entropy metal oxide cathode material is NaNi. 0.1 Mg 0.05 Cu 0.25 Fe 0.2 Mn 0.2 Zn 0.1 Ca 0.1 O2.

3. The high-entropy metal oxide cathode material according to claim 1 or 2, wherein, The particle size range of the high-entropy metal oxide cathode material is 0.1 μm-8 μm.

4. A method for preparing a high-entropy metal oxide cathode material according to any one of claims 1-3, comprising the following steps: According to the formula, at least one of the sources M1, M2, M3 and M4, a nickel source, an iron source, and a manganese source are mixed with a solvent to obtain a mixed solution; The mixed solution was subjected to spray pyrolysis to obtain an oxide composite precursor material; The oxide composite precursor material and sodium source are calcined to obtain the high-entropy metal oxide cathode material.

5. The method according to claim 4, wherein, The M1 source, M2 source, M3 source and M4 source are each independently selected from lithium source, magnesium source, copper source, zinc source, calcium source, vanadium source, aluminum source or zirconium source; Optionally, the lithium source includes lithium chloride; Optionally, the magnesium source includes magnesium chloride or magnesium sulfate, and may be magnesium chloride; Optionally, the copper source includes copper chloride or copper sulfate, and copper chloride may be selected as the copper source. Optionally, the zinc source includes zinc chloride or zinc sulfate, and may be zinc chloride; Optionally, the calcium source includes calcium chloride or calcium sulfate, and may be calcium chloride; Optionally, the vanadium source includes vanadium chloride; Optionally, the aluminum source includes aluminum chloride; Optionally, the zirconium source includes zirconium chloride; Optionally, the nickel source includes nickel chloride or nickel sulfate, and may be nickel chloride; Optionally, the iron source includes ferric chloride or ferric sulfate, and may be ferric chloride; Optionally, the manganese source includes manganese chloride or manganese sulfate, and may be manganese chloride; Optionally, the solvent includes water.

6. The method according to claim 4 or 5, wherein, The total concentration of all metal ions in the mixed solution is 1-3 mol / L.

7. The method according to any one of claims 4-6, wherein, The temperature of the spray in the spray pyrolysis is 200-240℃; Optionally, the pyrolysis in the spray pyrolysis is carried out under sintering conditions; Optionally, the sintering temperature is 630-670℃ and the time is 3-5h.

8. The method according to any one of claims 4-7, wherein, The molar ratio of all metal elements in the oxide composite precursor material to sodium in the sodium source is 1:

1. Optionally, the sodium source includes sodium carbonate.

9. The method according to any one of claims 4-8, wherein, The calcination temperature is 830-950℃, and the time is 9-11 hours.

10. A sodium-ion battery comprising a positive electrode, a negative electrode, an electrolyte, and a separator, wherein the positive electrode comprises a high-entropy metal oxide positive electrode material according to any one of claims 1-3.

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