High-entropy layered oxides having cation-anionic redox, methods for preparation, and uses

Abstract

An object is to provide a high-entropy layered oxide having cation-anion redox, a preparation method thereof, and uses thereof. 【Solution means】The general formula of the high-entropy layered oxide material is Na a [Li b Mg c Ni d Mn e M f O 2+β where M represents a transition metal element containing one or more elements among Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, W; a, b, c, d, e, f, 2+β represent the molar fractions of the corresponding elements respectively, and the relationship among a, b, c, d, e, f, 2+β satisfies b + c + d + e + f = 1 and a + b + 2c + 2d + 4e + mf = 2(2+β), where 0.85≦a≦1, 0.05≦b≦0.2, 0.05≦c≦0.2, 0.05≦d≦0.2, 0.2≦e≦0.6, 0.05≦f≦0.2, 0≦β≦0.1, m represents the oxidation number of M, and a, b, c, d, e, f satisfy the definition of high entropy, that is, satisfy, where R is the gas constant, N≧6, JPEG2026513375000016.jpg86 is any value of a, b, c, d, e, f, the high-entropy layered oxide material is an O3-type layered oxide material, the space group is, and the high-entropy layered oxide material is used as a positive electrode active material for a sodium ion secondary battery.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to the Chinese patent application filed with the Chinese National Intellectual Property Office on April 21, 2023, with application number 202310435218.9, and titled "High-entropy layered oxide having cation-anionic redox, method for preparation, and use."

[0002] Technical field The present invention relates to the technical field of materials, and more particularly to high-entropy layered oxide materials having cation-anionic redox, methods for preparing them, and their uses. [Background technology]

[0003] Against the backdrop of the "double carbon" crisis, the development of sustainable clean energy sources (wind, solar, tidal, etc.) is of great significance in reducing carbon emissions. However, these renewable energy sources are heavily dependent on natural conditions and possess characteristics such as intermittency and variability. High-performance secondary batteries are essential for building clean energy systems and realizing large-scale energy storage as the most efficient and convenient energy storage and conversion devices. Among the many energy storage technologies, physical energy storage such as pumped-storage hydroelectric energy storage, compressed air energy storage, and flywheel energy storage is constrained by factors such as geographical and practical conditions. On the other hand, electrochemical energy storage has advantages such as easy modularization, high energy conversion efficiency, high flexibility, and environmental friendliness, making it one of the most promising energy storage methods and an important guarantee for achieving the "double carbon" goal.

[0004] At present, among electrochemical energy storage technologies, lithium-ion batteries are widely used in daily life due to their advantages such as high energy density, long cycle life, small size, light weight, and pollution-free operation. However, the reserves of lithium resources in the Earth's crust are relatively small, with more than half of the world's lithium resources concentrated in South America. In China, 80% of lithium resources are imported, and the price of lithium carbonate is rising year by year, from approximately 50,000 RMB per ton in 2015 to around 500,000 RMB in 2022. Therefore, due to the constraints of resource reserves, lithium-ion batteries have difficulty simultaneously supporting the development of electric vehicles and large-scale energy storage, and there is a risk of them becoming a "bottleneck" in the future. Sodium-ion batteries, with their abundant and widely distributed resources and low cost, are considered a beneficial complement to lithium-ion batteries and are one of the ideal devices to be applied in the field of large-scale energy storage. Research and development of sodium-ion battery technology is strategically important and has recently attracted widespread attention again.

[0005] The development of high-performance electrode materials is crucial for the commercialization of sodium-ion batteries. In particular, the cathode material plays a decisive role in the overall energy density and electrochemical performance of the battery. Currently, research on sodium-ion cathode materials is still in the early stages of laboratory exploration. Currently, research on cathode materials mainly focuses on transition metal oxides with layered structures, such as sodium oxide. x The focus is on MO2 (where M represents one or more 3d or 4d transition metals). Further improving the specific capacity and energy density of layered oxide materials is an effective means of reducing costs and expanding the application scenarios of sodium-ion batteries. Inspired by the "lithium-rich" cathodes of high-specific-capacity lithium-ion batteries due to anion redox reactions, a new strategy has been developed to improve the energy density of sodium-ion batteries by activating the redox reaction of lattice oxygen in sodium-based oxides. For example, P2-type Na based on anion redox reactions. 0.72 Li 0.24 Mn 0.76O2, as a cathode material for sodium-ion batteries, possesses a high reversible ratio capacity (270 mAh / g) and a maximum energy density (700 Wh / kg) in the 1.5V to 4.5V range. However, inducing the redox reaction of lattice oxygen that results in higher capacity usually requires a high charge termination voltage (4.4V), leading to unwanted structural degradation and serious side reactions. Therefore, many oxygen valency change material electrodes suffer from practical problems such as dynamic hysteresis, voltage hysteresis, oxygen desorption, and significant capacity degradation. These problems have greatly hindered the practical application of oxygen valency change materials in sodium-ion batteries. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Embodiments of the present invention provide a high-entropy layered oxide material having cation-anion redox, a method for preparing it, and its use. The present invention primarily provides charge compensation during the charge-discharge process based on the valence change of electrochemically active transition metal cations and anions (lattice oxygen). Due to the high-entropy arrangement of the transition metals, the material exhibits excellent structural stability and long cycle life characteristics. A half-cell assembled with a positive electrode prepared using this material and a metallic sodium negative electrode shows almost no capacity degradation even after 400 cycles, and its cycle life is 4 to 5 times that of a normal oxygen valence change material, demonstrating excellent cycle stability and cycle life, and high practical value. Furthermore, the method for preparing the high-entropy layered oxide material of the present invention is simple. Sodium-ion batteries containing the high-entropy layered oxide material of the present invention can be used in solar power generation, wind power generation, peak adjustment in smart grids, distributed power plants, backup power sources, or large-scale energy storage facilities for communication base stations. [Means for solving the problem]

[0007] In a first embodiment, an example of the present invention provides a high-entropy layered oxide material having a cation-anion redox, the general formula of the high-entropy layered oxide material being Naa [Li b Mg c Ni d Mn e M f O 2+β is represented by where M represents a transition metal element containing one or more elements selected from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W; a, b, c, d, e, f, and 2 + β represent the molar fractions of the corresponding elements, respectively; the relationship among a, b, c, d, e, f, and 2 + β satisfies b + c + d + e + f = 1 and a + b + 2c + 2d + 4e + mf = 2(2 + β), where 0.85 ≤ a ≤ 1, 0.05 ≤ b ≤ 0.2, 0.05 ≤ c ≤ 0.2, 0.05 ≤ d ≤ 0.2, 0.2 ≤ e ≤ 0.6, 0.05 ≤ f ≤ 0.2, 0 ≤ β ≤ 0.1, and m represents the oxidation number of the said M. a, b, c, d, e, f satisfy the definition of high entropy, that is, they satisfy the following formula [Number] where R is the gas constant and N ≥ 6. [Number] is any value of a, b, c, d, e, f. The high-entropy layered oxide material is an O3-type layered oxide material, and the space group is [Number] is The high-entropy layered oxide material is used as a positive electrode active material for a sodium-ion secondary battery. During the first-cycle charging, the transition metal M ions with electrochemical activity first lose electrons, and then the oxygen ions in the crystal lattice lose electrons. The average valence of the oxygen ions increases from -2 to a valence between -2 and -1. During the first-discharge process, the transition metal M ions with electrochemical activity and the oxygen ions with a high valence regain electrons again. After the second cycle, the oxygen ions and the transition metal M ions with electrochemical activity transfer electrons during the charge-discharge process.

[0008] In a second embodiment, an example of the present invention provides a method for preparing a high-entropy layered oxide material having the cation-anion redox described in the first embodiment, wherein the method is a solid-phase method. A precursor powder is obtained by proportionally mixing a sodium source material in a stoichiometric ratio of 100% to 108% of the required sodium, a lithium source material in a stoichiometric ratio of 100% to 108% of the required lithium, a magnesium source material in the required stoichiometric ratio, a nickel source material, a manganese source material, and a compound M, and then uniformly mixing them. The obtained precursor powder is placed in a crucible, heated in a high-temperature furnace under an air atmosphere, cooled, removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox. Includes.

[0009] Preferably, the sodium source material is sodium carbonate. The lithium source material comprises lithium carbonate and / or lithium hydroxide. The magnesium source material includes magnesium oxide and / or magnesium carbonate. The aforementioned nickel source material is nickel oxide. The manganese source material is manganese dioxide and / or dimanganese trioxide. The compound M comprises an oxide and / or a carbonate of M, where M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The aforementioned method of uniform mixing is grinding and mixing or ball mill mixing. The aforementioned heat treatment specifically involves heat treatment at a temperature of 800°C to 1000°C for 2 to 24 hours.

[0010] In a third embodiment, an example of the present invention provides a method for preparing a high-entropy layered oxide material having the cation-anion redox described in the first embodiment, wherein the method is a sol-gel method. Dissolve 100% to 108% of the required sodium stoichiometric ratio of sodium source material, 100% to 108% of the required lithium-containing water-soluble salt or tetrabutyl titanate, and the required stoichiometric ratio of magnesium, nickel, manganese, and M-containing water-soluble salt or tetrabutyl titanate in a solvent, and add citric acid to form a precursor gel. The precursor gel is placed in a crucible and then placed in a high-temperature furnace, where it is subjected to low-temperature pretreatment in an air atmosphere to obtain a pre-treated powder. The aforementioned pre-treated powder is subjected to high-temperature heat treatment in an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox. Includes.

[0011] Preferably, the sodium source material is one or more of sodium acetate, sodium nitrate, sodium carbonate, and sodium sulfate. M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The solvent includes anhydrous ethanol or deionized water. The aforementioned low-temperature pretreatment specifically involves calcining at a temperature of 250°C to 500°C for 2 to 6 hours. The aforementioned high-temperature heat treatment specifically involves heat treatment at 800°C to 1000°C for 2 to 24 hours.

[0012] In a fourth embodiment, an example of the present invention provides a method for preparing a high-entropy layered oxide material having the cation-anionic redox described in the first embodiment, wherein the method is a spray drying method. The process involves mixing a sodium source material in proportion to 100% to 108% of the required sodium stoichiometric ratio, a lithium source material in proportion to 100% to 108% of the required lithium stoichiometric ratio, a magnesium source material in the required stoichiometric ratio, a nickel source material, a manganese source material, and a compound M in proportion to obtain a precursor after uniform mixing. After adding a predetermined ratio of solvent to the precursor, a slurry is formed by uniformly stirring. The slurry is placed in a spray dryer and spray-dried to obtain a precursor powder. The precursor powder is placed in a crucible, placed in a high-temperature furnace, and heat-treated under an air atmosphere. The heat-treated precursor powder is pulverized to obtain the high-entropy layered oxide material, Includes.

[0013] Preferably, the sodium source material is sodium carbonate. The lithium source material comprises lithium carbonate and / or lithium hydroxide. The magnesium source material includes magnesium oxide and / or magnesium carbonate. The aforementioned nickel source material is nickel oxide. The manganese source material is manganese dioxide and / or dimanganese trioxide. The compound M comprises an oxide and / or a carbonate of M, where M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The aforementioned method of uniform mixing is grinding and mixing or ball mill mixing. The solvent includes anhydrous ethanol or deionized water. The aforementioned heat treatment method specifically involves heat treatment at a temperature of 800°C to 1000°C for 2 to 24 hours. The inlet temperature of the spray dryer is 150°C to 190°C, the outlet temperature is 70°C to 100°C, and the supply rate is 200 mL / h to 600 mL / h.

[0014] In a fifth embodiment, an embodiment of the present invention provides a positive electrode plate for a sodium-ion secondary battery, the positive electrode plate comprising a current collector, a conductive additive and adhesive coated on the current collector, and a high-entropy layered oxide material having the cation-anion redox described in the first embodiment.

[0015] In a sixth embodiment, an example of the present invention provides a sodium-ion secondary battery having the positive electrode plate described in the fifth embodiment above.

[0016] In a seventh embodiment, the embodiment of the present invention provides the use of the sodium-ion secondary battery described in the sixth embodiment above, the sodium-ion secondary battery being used in mobile devices, means of transport, renewable energy generation, peak regulating in smart grids, distributed power plants, backup power sources, or energy storage equipment for communication base stations. [Effects of the Invention]

[0017] In the high-entropy layered oxide material having cation-anion redox according to an embodiment of the present invention, each element in the transition metal layer is distributed disorderly, and during the charging process, nickel and the transition metal element M first take charge compensation, followed by lattice oxygen. Due to the high-entropy arrangement of the transition metals, the starting voltage for oxygen valency change is effectively reduced, and the material completes the charging process when charged to 4.2V, avoiding the significant decomposition of the electrolyte that occurs when conventional oxygen valency change materials require charging above 4.2V, providing a specific capacity of approximately 200mAh / g. Furthermore, the high-entropy arrangement mitigates structural changes in the material, and the material exhibits excellent structural stability. Finally, the material exhibits excellent long-term cycle stability, maintaining a capacity retention rate of 95% or more even after 400 cycles under 1C charge / discharge conditions, and has great utility value. The sodium-ion secondary battery using the high-entropy layered oxide material of the present invention can be used for peak adjustment in smart grids such as new energy generation, as a backup power source, or for large-scale energy storage facilities in communication base stations.

[0018] The method for preparing a high-entropy layered oxide material having cation-anion redox according to an embodiment of the present invention is easy to operate and facilitates the realization of large-scale production.

[0019] The technical proposal of embodiments of the present invention will be described in more detail below with reference to the drawings and examples. [Brief explanation of the drawing]

[0020] [Figure 1] This is a schematic diagram of the high-entropy arrangement of interlayer elements in a high-entropy layered oxide material according to an embodiment of the present invention. [Figure 2] This is a flowchart illustrating a method for preparing a high-entropy layered oxide material by a solid-phase method according to an embodiment of the present invention. [Figure 3] This is a flowchart illustrating a method for preparing a high-entropy layered oxide material by a sol-gel method according to an embodiment of the present invention. [Figure 4] This is a flowchart illustrating a method for preparing a high-entropy layered oxide material by spray drying according to an embodiment of the present invention. [Figure 5] These are the X-ray diffraction (XRD) patterns of high-entropy layered oxide materials according to Examples 1 to 5 of the present invention. [Figure 6] High-entropy layered oxide material according to Example 1 of the present invention <100> This is a transmission electron microscope image corrected for spherical aberration in terms of crystal orientation. [Figure 7] This is a diagram of the initial cycle charge-discharge curve of a sodium-ion secondary battery according to Embodiment 1 of the present invention. [Figure 8] This is a cycle capacity curve diagram of a sodium-ion secondary battery according to Example 1 of the present invention. [Figure 9] This is a diagram of the initial cycle charge-discharge curve of a sodium-ion secondary battery according to Example 2 of the present invention. [Figure 10] This is a diagram showing the initial charge-discharge curve of a sodium-ion secondary battery according to Embodiment 3 of the present invention. [Figure 11] This is a diagram of the initial cycle charge-discharge curve of a sodium-ion secondary battery according to Embodiment 4 of the present invention. [Figure 12] This is a diagram of the initial cycle charge-discharge curve of a sodium-ion secondary battery according to Example 5 of the present invention. [Figure 13] This is a diagram of the initial cycle charge-discharge curve of a sodium-ion secondary battery according to Embodiment 6 of the present invention. [Modes for carrying out the invention]

[0021] The present invention will be described in more detail below with reference to the drawings and specific embodiments, but these embodiments are merely for the purpose of explaining the present invention in more detail and should be understood as not intended to limit the present invention in any way, that is, they are not intended to limit the scope of protection of the present invention.

[0022] Examples of the present invention provide a high-entropy layered oxide material having a cation-anion redox, the general formula of which is Na a [Li b Mg c Ni d Mn e M f ]O 2+β This is expressed as follows: where M represents a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W; a, b, c, d, e, f, and 2+β each represent the mole fraction of the corresponding element; the relationships between a, b, c, d, e, f, and 2+β satisfy b+c+d+e+f=1 and a+b+2c+2d+4e+mf=2(2+β), where 0.85≦a≦1, 0.05≦b≦0.2, 0.05≦c≦0.2, 0.05≦d≦0.2, 0.2≦e≦0.6, 0.05≦f≦0.2, and 0≦β≦0.1; and m represents the oxidation state of M.

[0023] The above a, b, c, d, e, and f must satisfy the definition of high entropy, that is, they must satisfy the requirements of the following equation:

number

number

[0024] The gas constant is equivalent to the Boltzmann constant, and its value is 8.314 J / (mol·K).

[0025]

number

[0026] In the above formula

number

[0027] Figure 1 shows a schematic diagram of the high-entropy configuration of transition metals. In the figure, M1, M2, M3, M4, M5, and M6 represent the transition metals Mn, Ni, Li, Mg, and two of the above transition metal elements M, respectively. It can be seen that the transition metal layer contains at least five different transition metal elements, the elemental arrangement in each layer is disordered, and the types of elements may overlap.

[0028] By employing the high-entropy configuration of the above-mentioned transition metals, the present invention results in a highly disordered arrangement of transition metal elements during the charge-discharge process. As a result, the valence state of some elements changes while that of others remains unchanged during the cycle. This suppresses volume changes in the unit cell and avoids the collapse of the crystal lattice, thereby mitigating structural changes in the material. Consequently, the high-entropy layered oxide material of the present invention exhibits excellent structural stability.

[0029] The high-entropy layered oxide material of the present invention is an O3-type layered oxide material, and the space group is

number

[0030] The above-mentioned high-entropy layered oxide material is used as a positive electrode active material for sodium-ion secondary batteries. During the first cycle of charging, electrochemically active transition metal M ions lose electrons first, followed by oxygen ions in the crystal lattice, causing the average valency of oxygen ions to rise from -2 to a valency between -2 and -1. During the first discharge process, electrochemically active transition metal M ions and oxygen ions with high valencies regain electrons. From the second cycle onward, oxygen ions and electrochemically active transition metal M ions exchange electrons during the charge and discharge process.

[0031] The embodiments of the present invention provide three methods for preparing the above-mentioned high-entropy layered oxide material: a solid-phase method, a sol-gel method, and a spray-drying method. The preparation methods for obtaining the material will be described below.

[0032] Examples of the present invention provide a method for preparing a high-entropy layered oxide material having the above-described cation-anion redox, the method being a solid-phase method, and specifically including the following steps as shown in Figure 2.

[0033] In step 210, a sodium source material in the required stoichiometric ratio of sodium (100% to 108%), a lithium source material in the required stoichiometric ratio of lithium (100% to 108%), a magnesium source material in the required stoichiometric ratio, a nickel source material, a manganese source material, and a compound M are mixed in proportion to obtain a precursor powder after homogeneous mixing. Here, the sodium source material is sodium carbonate, the lithium source material includes lithium carbonate and / or lithium hydroxide, the magnesium source material includes magnesium oxide and / or magnesium carbonate, the nickel source material is nickel oxide, and the manganese source material includes manganese dioxide and / or dimanganese trioxide. The compound of M comprises an oxide and / or carbonate of M, where M is a transition metal element comprising one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. Methods for uniform mixing include grinding and mixing or ball milling.

[0034] In step 220, the obtained precursor powder is placed in a crucible, heated in a high-temperature furnace under an air atmosphere, cooled, removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox.

[0035] Here, the heat treatment specifically involves heat treatment at a temperature of 800°C to 1000°C for 2 to 24 hours.

[0036] The present invention provides another method for preparing a high-entropy layered oxide material having the above-described cation-anion redox, the method being a sol-gel method, and specifically includes the following steps, as shown in Figure 3.

[0037] Step 310: Dissolve 100% to 108% of the required sodium stoichiometric ratio of sodium source material, 100% to 108% of the required stoichiometric ratio of lithium-containing water-soluble salt or tetrabutyl titanate, and the required stoichiometric ratio of magnesium, nickel, manganese, and M-containing water-soluble salt or tetrabutyl titanate in a solvent, add citric acid to form a precursor gel, Here, the sodium source material is one or more of sodium acetate, sodium nitrate, sodium carbonate, and sodium sulfate. M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The solvent includes anhydrous ethanol or deionized water.

[0038] In step 320, the precursor gel is placed in a crucible and placed in a high-temperature furnace, where it is subjected to low-temperature pretreatment in an air atmosphere to obtain a pre-treated powder. Here, low-temperature pretreatment specifically involves calcining at a temperature of 250°C to 500°C for 2 to 6 hours.

[0039] In step 330, the pre-treated powder is subjected to high-temperature heat treatment in an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox. Here, high-temperature heat treatment specifically refers to heat treatment at 800°C to 1000°C for 2 to 24 hours.

[0040] Examples of the present invention provide a method for preparing a high-entropy layered oxide material having the above-described cation-anion redox, the method being a spray-drying method, and specifically including the following steps as shown in Figure 4.

[0041] In step 410, a sodium source material in 100% to 108% of the required sodium stoichiometric ratio, a lithium source material in 100% to 108% of the required lithium stoichiometric ratio, a magnesium source material in the required stoichiometric ratio, a nickel source material, a manganese source material, and a compound M are mixed in proportion to obtain a precursor after homogeneous mixing. Here, the sodium source material is sodium carbonate, the lithium source material includes lithium carbonate and / or lithium hydroxide, the magnesium source material includes magnesium oxide and / or magnesium carbonate, the nickel source material is nickel oxide, and the manganese source material includes manganese dioxide and / or dimanganese trioxide. The compound of M comprises an oxide and / or carbonate of M, where M is a transition metal element comprising one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. Methods for uniform mixing include grinding and mixing or ball milling.

[0042] In step 420, after adding a predetermined ratio of solvent to the precursor, a slurry is formed by uniformly stirring. Here, the solvent includes anhydrous ethanol or deionized water.

[0043] In step 430, the slurry is placed in a spray dryer and spray-dried to obtain a precursor powder. The inlet temperature of the spray dryer is 150°C to 190°C, the outlet temperature is 70°C to 100°C, and the supply rate is 200 mL / h to 600 mL / h.

[0044] In step 440, the precursor powder is placed in a crucible and then placed in a high-temperature furnace, where it is heat-treated under an air atmosphere. Here, the heat treatment method specifically involves heat treatment at a temperature of 800°C to 1000°C for 2 to 24 hours.

[0045] In step 450, the heat-treated precursor powder is pulverized to obtain a high-entropy layered oxide material.

[0046] The above-described high-entropy layered oxide material having cation-anion redox according to an embodiment of the present invention can be used as a positive electrode active material to prepare a slurry together with a conductive additive and an adhesive. By applying the slurry onto a current collector, a positive electrode plate is obtained, and a sodium-ion secondary battery is assembled by combining the positive electrode plate, a negative electrode, a separator placed between the positive and negative electrodes, and an electrolyte according to a conventional manufacturing process. Specifically, metallic sodium is used for the negative electrode, or the negative electrode comprises a negative electrode current collector and a negative electrode material in the negative electrode current collector, and the negative electrode material comprises a negative electrode active material, a conductive additive, and an adhesive.

[0047] The sodium-ion secondary battery assembled as described above can be used in mobile devices, transportation systems, renewable energy generation, peak load balancing in smart grids, distributed power plants, backup power sources, or energy storage equipment for communication base stations.

[0048] To better understand the proposed technology according to the present invention, the preparation process and properties of the high-entropy layered oxide material having cation-anionic redox according to the present invention will be described below with reference to several specific examples.

[0049] (Example 1) The preparation process and performance testing of a high-entropy layered oxide material having cation-anionic redox according to the present invention specifically uses a solid-phase method and includes the following steps.

[0050] (1) Mix Na2CO3 (reagent grade, 3% excess), Li2CO3 (reagent grade, 3% excess), MgO (reagent grade), NiO (reagent grade), CuO (reagent grade), MnO2 (reagent grade), and TiO2 (reagent grade) uniformly in the required stoichiometric ratio to obtain a precursor powder.

[0051] (2) The obtained precursor powder is placed in a crucible, placed in a high-temperature furnace, treated at 900°C for 15 hours under an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox, the chemical formula of which is Na 0.9 Li 0.1 Mg 0.1 Ni 0.1 Cu 0.1 Mn 0.4 Ti 0.2 It is O2.

[0052] High-entropy layered oxide material Na of this embodiment 0.9 Li 0.1 Mg 0.1 Ni 0.1 Cu 0.1 Mn 0.4 Ti 0.2 Figure 5 shows the XRD of O2, and analysis from the X-ray diffraction pattern reveals that Na 0.9 Li 0.1 Mg 0.1 Ni 0.1 Cu 0.1 Mn 0.4 Ti 0.2 The crystalline structure of O2 is an O3-type layered oxide.

[0053] High-entropy layered oxide material Na of this embodiment 0.9 Li 0.1 Mg 0.1 Ni 0.1 Cu 0.1 Mn 0.4 Ti 0.2O2 <100> From spherical aberration-corrected transmission electron microscope images in the crystal orientation, it was observed that atomic spots in the transition metal layer are distributed in a disordered manner with varying brightness levels due to differences in the atomic masses of different elements, indicating a disordered arrangement of different transition metals.

[0054] High-entropy layered oxide material Na of this embodiment 0.9 Li 0.1 Mg 0.1 Ni 0.1 Cu 0.1 Mn 0.4 Ti 0.2 The entropy value of O2 is calculated as S = -R(0.9ln0.9 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.4ln0.4 + 0.2ln0.2) = 1.70R, which satisfies the requirements for high-entropy design of the material of the present invention.

[0055] A sodium-ion secondary battery is fabricated using the high-entropy layered oxide material prepared above as the active material for the battery cathode. The specific steps are as follows. Prepared Na 0.9 Li 0.1 Mg 0.1 Ni 0.1 Cu 0.1 Mn 0.4 Ti 0.2 O2 powder, acetylene black, and polyvinylidene fluoride (PVDF) adhesive are mixed in a mass ratio of 80:10:10. An appropriate amount of N-methylpyrrolidone (NMP) solution is added, and the mixture is ground in a dry environment at room temperature to form a slurry. The slurry is then uniformly applied to the aluminum foil of the current collector, dried under an infrared lamp, and then (8 × 8) mm 2 Cut the electrode plates. After drying the electrode plates at 110°C for 10 hours under vacuum conditions, transfer them to a glove box and set them aside.

[0056] The simulated battery is assembled in a glove box under an argon atmosphere. A sodium metal is used as the counter electrode, and a solution of propylene carbonate (PC) / ethylene carbonate (EC) / diethyl carbonate (DEC) (volume ratio of PC:EC:DEC = 1:1:1) containing 1 mol / L of NaClO4 is used as the electrolyte. A GF / D glass fiber membrane is used as the battery separator, and a CR2032 button cell is assembled according to a normal process.

[0057] Specifically, the battery testing method involved using a constant current charge / discharge mode, with a current density of 20 mA / g. The discharge termination voltage was 2.0 V, and the charge termination voltage was 4.2 V.

[0058] The initial cycle charge-discharge curve is shown in Figure 7, confirming that the battery's reversible capacity in its first cycle is 165 mAh / g.

[0059] The cycle curve is shown in Figure 8, confirming that the battery capacity hardly deteriorates even after 130 cycles.

[0060] (Example 2) The preparation process and performance testing of a high-entropy layered oxide material having cation-anionic redox according to the present invention specifically uses a solid-phase method and includes the following steps.

[0061] (1) Mix Na2CO3 (reagent grade, 3% excess), Li2CO3 (reagent grade, 3% excess), MgO (reagent grade), NiO (reagent grade), ZnO (reagent grade), MnO2 (reagent grade), and TiO2 (reagent grade) uniformly in the required stoichiometric ratio to obtain a precursor powder.

[0062] (2) The obtained precursor powder is placed in a crucible, placed in a high-temperature furnace, treated at 900°C for 15 hours under an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox, the chemical formula of which is Na 0.9 Li 0.1 Mg 0.1 Ni 0.1 Zn 0.1Mn 0.4 Ti 0.2 It is O2.

[0063] High-entropy layered oxide material Na of this embodiment 0.9 Li 0.1 Mg 0.1 Ni 0.1 Zn 0.1 Mn 0.4 Ti 0.2 Figure 5 shows the XRD of O2, and analysis from the X-ray diffraction pattern reveals that Na 0.9 Li 0.1 Mg 0.1 Ni 0.1 Zn 0.1 Mn 0.4 Ti 0.2 The crystalline structure of O2 is an O3-type layered oxide.

[0064] Na prepared in this example 0.9 Li 0.1 Mg 0.1 Ni 0.1 Zn 0.1 Mn 0.4 Ti 0.2 The entropy value of O2 is calculated as S = -R(0.9ln0.9 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.4ln0.4 + 0.2ln0.2) = 1.70R, which satisfies the definition of high entropy.

[0065] A sodium-ion secondary battery was fabricated and tested using the high-entropy layered oxide material prepared above as the active material for the battery cathode. The specific process for assembling and testing the CR2032 button cell was the same as in Example 1.

[0066] The initial cycle charge-discharge curve is shown in Figure 9, confirming that the battery's initial charge capacity was 165.6 mAh / g and its initial discharge capacity was 139 mAh / g.

[0067] (Example 3) The preparation process and performance test of the high-entropy layered oxide material with cation-anion redox according to the present invention specifically use the solid-phase method and include the following steps.

[0068] (1) Mix Na2CO3 (reagent grade, 3% excess), Li2CO3 (reagent grade, 3% excess), MgO (reagent grade), NiO (reagent grade), Fe2O3 (reagent grade), MnO2 (reagent grade), and TiO2 (reagent grade) uniformly in the required stoichiometric ratio to obtain precursor powder.

[0069] (2) Put the obtained precursor powder into a crucible, place it in a high-temperature furnace, treat it at 900 °C for 15 hours in an air atmosphere, cool it and take it out, and then pulverize it to obtain a high-entropy layered oxide material with cation-anion redox. The chemical formula is Na 0.9 Li 0.1 Mg 0.1 Ni 0.1 Fe 0.2 Mn 0.4 Ti 0.1 O2.

[0070] The XRD of the high-entropy layered oxide material Na 0.9 Li 0.1 Mg 0.1 Ni 0.1 Fe 0.2 Mn 0.4 Ti 0.1 O2 in this example is shown in Figure 5. Analyzing from the X-ray diffraction pattern, the crystal structure of Na 0.9 Li 0.1 Mg 0.1 Ni 0.1 Fe 0.2 Mn 0.4 Ti 0.1 O2 is an O3-type layered oxide.

[0071] The Na 0.9 Li 0.1 Mg 0.1 Ni 0.1 Fe 0.2 Mn 0.4 Ti 0.1The entropy value of O2 is calculated as S = -R(0.9ln0.9 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.2ln0.2 + 0.4ln0.4 + 0.1ln0.1) = 1.70R, which satisfies the definition of high entropy.

[0072] A sodium-ion secondary battery was fabricated and tested using the high-entropy layered oxide material prepared above as the active material for the battery cathode. The specific process for assembling and testing the CR2032 button cell was the same as in Example 1.

[0073] The initial cycle charge-discharge curve is shown in Figure 10, confirming that the battery's initial charge capacity was 166.2 mAh / g and its initial discharge capacity was 155 mAh / g.

[0074] (Example 4) The preparation process and performance testing of a high-entropy layered oxide material having cation-anionic redox according to the present invention specifically uses a solid-phase method and includes the following steps.

[0075] (1) Na2CO3 (reagent grade, 3% excess), Li2CO3 (reagent grade, 3% excess), MgO (reagent grade), NiO (reagent grade), Fe2O3 (reagent grade), MnO2 (reagent grade), TiO2 (reagent grade), and Nb2O5 (reagent grade) are uniformly mixed in the required stoichiometric ratio to obtain a precursor powder.

[0076] (2) The obtained precursor powder is placed in a crucible, placed in a high-temperature furnace, treated at 900°C for 15 hours under an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox, the chemical formula of which is Na 0.95 Li 0.1 Mg 0.1 Ni 0.1 Fe 0.2 Mn 0.4 Ti 0.05 Nb 0.05 It is O2.

[0077] High-entropy layered oxide material Na of this embodiment 0.95 Li 0.1 Mg 0.1 Ni 0.1 Fe 0.2 Mn 0.4 Ti 0.05 Nb 0.05 Figure 5 shows the XRD of O2, and analysis from the X-ray diffraction pattern reveals that Na 0.95 Li 0.1 Mg 0.1 Ni 0.1 Fe 0.2 Mn 0.4 Ti 0.05 Nb 0.05 The crystal structure of O2 was found to be an O3-type layered oxide.

[0078] Na prepared in this example 0.95 Li 0.1 Mg 0.1 Ni 0.1 Fe 0.2 Mn 0.4 Ti 0.05 Nb 0.05 The entropy value of O2 is calculated as S = -R(0.95ln0.95 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.2ln0.2 + 0.4ln0.4 + 0.05ln0.05 + 0.05ln0.05) = 1.73R, which satisfies the definition of high entropy.

[0079] A sodium-ion secondary battery was fabricated and tested using the high-entropy layered oxide material prepared above as the active material for the battery cathode. The specific process for assembling and testing the CR2032 button cell was the same as in Example 1.

[0080] The initial cycle charge / discharge curve is shown in Figure 11, confirming that the battery's initial charge capacity was 158.7 mAh / g and its initial discharge capacity was 128.5 mAh / g.

[0081] (Example 5) The preparation process and performance testing of a high-entropy layered oxide material having cation-anionic redox according to the present invention specifically uses a solid-phase method and includes the following steps.

[0082] (1) Na2CO3 (reagent grade, 3% excess), Li2CO3 (reagent grade, 3% excess), MgO (reagent grade), NiO (reagent grade), CuO (reagent grade), MnO2 (reagent grade), RuO2 (reagent grade), and MoO3 (reagent grade) are uniformly mixed in the required stoichiometric ratio to obtain a precursor powder.

[0083] (2) The obtained precursor powder is placed in a crucible, placed in a high-temperature furnace, treated at 900°C for 15 hours under an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox, the chemical formula of which is Na 0.9 Li 0.1 Mg 0.1 Ni 0.15 Cu 0.1 Mn 0.4 Ru 0.1 Mo 0.05 It is O2.

[0084] High-entropy layered oxide material Na of this embodiment 0.9 Li 0.1 Mg 0.1 Ni 0.15 Cu 0.1 Mn 0.4 Ru 0.1 Mo 0.05 Figure 5 shows the XRD of O2, and analysis from the X-ray diffraction pattern reveals that Na 0.9 Li 0.1 Mg 0.1 Ni 0.15 Cu 0.1 Mn 0.4 Ru 0.1 Mo 0.05 The crystal structure of O2 was found to be an O3-type layered oxide.

[0085] Na prepared in this example 0.9 Li 0.1 Mg 0.1 Ni 0.15 Cu 0.1 Mn0.4 Ru 0.1 Mo 0.05 The entropy value of O2 is calculated as S = -R(0.9ln0.9 + 0.1ln0.1 + 0.1ln0.1 + 0.15ln0.15 + 0.1ln0.1 + 0.4ln0.4 + 0.1ln0.1 + 0.05ln0.05) = 1.82R, which satisfies the definition of high entropy.

[0086] A sodium-ion secondary battery was fabricated and tested using the high-entropy layered oxide material prepared above as the active material for the battery cathode. The specific process for assembling and testing the CR2032 button cell was the same as in Example 1.

[0087] The initial cycle charge / discharge curve is shown in Figure 12, confirming that the battery's initial charge capacity was 186.5 mAh / g and its initial discharge capacity was 156 mAh / g.

[0088] (Example 6) The preparation process and performance testing of a high-entropy layered oxide material having cation-anionic redox according to the present invention specifically uses a solid-phase method and includes the following steps.

[0089] (1) Na2CO3 (reagent grade, 3% excess), Li2CO3 (reagent grade, 3% excess), MgO (reagent grade), NiO (reagent grade), CuO (reagent grade), MnO2 (reagent grade), RuO2 (reagent grade), TiO2 (reagent grade), and WO3 (reagent grade) are uniformly mixed in the required stoichiometric ratio to obtain a precursor powder.

[0090] (2) The obtained precursor powder is placed in a crucible, placed in a high-temperature furnace, treated at 900°C for 15 hours under an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox, the chemical formula of which is Na 0.9 Li 0.1 Mg 0.1 Ni 0.15 Cu 0.1 Mn 0.4 Ru 0.05 Ti0.05 W 0.05 It is O2.

[0091] High-entropy layered oxide material Na prepared in this example 0.9 Li 0.1 Mg 0.1 Ni 0.15 Cu 0.1 Mn 0.4 Ru 0.05 Ti 0.05 W 0.05 Figure 5 shows the XRD of O2, and analysis from the X-ray diffraction pattern reveals that Na 0.9 Li 0.1 Mg 0.1 Ni 0.15 Cu 0.1 Mn 0.4 Ru 0.05 Ti 0.05 W 0.05 The crystal structure of O2 was found to be an O3-type layered oxide.

[0092] Na prepared in this example 0.9 Li 0.1 Mg 0.1 Ni 0.15 Cu 0.1 Mn 0.4 Ru 0.05 Ti 0.05 W 0.05 The entropy value of O2 is calculated as S = -R(0.9ln0.9 + 0.1ln0.1 + 0.1ln0.1 + 0.15ln0.15 + 0.1ln0.1 + 0.4ln0.4 + 0.05ln0.05 + 0.05ln0.05 + 0.05ln0.05) = 1.89R, which satisfies the definition of high entropy.

[0093] A sodium-ion secondary battery was fabricated and tested using the high-entropy layered oxide material prepared above as the active material for the battery cathode. The specific process for assembling and testing the CR2032 button cell was the same as in Example 1.

[0094] The initial cycle charge / discharge curve is shown in Figure 13, confirming that the battery's initial charge capacity was 190 mAh / g and its initial discharge capacity was 148 mAh / g.

[0095] (Example 7) The preparation process and performance testing of a high-entropy layered oxide material having cation-anionic redox according to the present invention specifically uses the sol-gel method and includes the following steps.

[0096] (1) Take NaC2H3O2 (reagent grade, 3% excess), LiC2H3O2 (reagent grade, 3% excess), Mg(C2H3O2)2 (reagent grade), Ni(C2H3O2)2 (reagent grade), Cu(C2H3O2)2 (reagent grade), Mn(C2H3O2)2 (reagent grade), and Sb(C2H3O2)3 (reagent grade) in stoichiometric ratios, dissolve them sequentially in deionized water, and add citric acid to form a precursor gel.

[0097] (2) The precursor gel is placed in a crucible and placed in a high-temperature furnace, and calcined at a temperature of 300°C for 3 hours in an air atmosphere to obtain a pre-treated powder.

[0098] (3) The pre-treated powder is heat-treated at 900°C for 5 hours in an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox, the chemical formula of which is NaLi 0.1 Mg 0.1 Ni 0.1 Cu 0.1 Mn 0.5 S 0.1 It is O2.

[0099] The NaLi prepared in this example 0.1 Mg 0.1 Ni 0.1 Cu 0.1 Mn 0.5 S 0.1The entropy value of O2 is calculated as S = -R(ln1 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.5ln0.5 + 0.1ln0.1) = 1.5R, which satisfies the definition of high entropy.

[0100] (Example 8) The preparation process and performance test of a high-entropy layered oxide material having a cation-anionic redox according to the present invention specifically uses a spray drying method and includes the following steps.

[0101] (1) Na2CO3 (reagent grade, 3% excess), Li2CO3 (reagent grade, 3% excess), MgO (reagent grade), NiO (reagent grade), ZnO (reagent grade), MnO2 (reagent grade), and La2O3 (reagent grade) are uniformly mixed in the required stoichiometric ratio to obtain a precursor.

[0102] (2) After adding anhydrous ethanol in a predetermined ratio to the precursor, a slurry is formed by uniformly stirring.

[0103] (3) The slurry is placed in a spray dryer and spray-dried to obtain a precursor powder. Here, the inlet temperature of the spray dryer is 160°C, the outlet temperature is 80°C, and the feed rate is 400 mL / h.

[0104] (4) The precursor powder is placed in a crucible, placed in a high-temperature furnace, and heat-treated at 900°C for 10 hours under an air atmosphere. After cooling and pulverization, a high-entropy layered oxide material is obtained, whose chemical formula is NaLi 0.1 Mg 0.1 Ni 0.1 Zn 0.1 Mn 0.5 La 0.1 It is O2.

[0105] The NaLi prepared in this example 0.1 Mg 0.1 Ni 0.1 Zn 0.1 Mn 0.5 La 0.1The entropy value of O2 is calculated as S = -R(ln1 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.1ln0.1 + 0.5ln0.5 + 0.1ln0.1) = 1.5R, which satisfies the definition of high entropy. [Industrial applicability]

[0106] The high-entropy layered oxide material having cation-anion redox according to the embodiment of the present invention activates the redox reaction of lattice oxygen with Li and Mg, and cooperates with the redox reaction of other interlayered transition metals having high electrochemical activity and high disorder to provide high specific capacity, and consequently improve energy density and cycle stability. Sodium-ion secondary batteries using the high-entropy layered oxide material of the present invention have an appropriate voltage range, relatively low cost, and high energy density, and can be used for peak adjustment in smart grids such as new energy generation, backup power supplies, large-scale energy storage facilities for communication base stations, or power supplies for low-speed electric vehicles, electric boats, motorcycles, etc.

[0107] The specific embodiments described above further elaborate on the objectives, technical proposals, and beneficial effects of the present invention. These are merely specific embodiments of the present invention and are not intended to limit the scope of protection. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are all included within the scope of protection.

[0108] (Note) (Note 1) A high-entropy layered oxide material having a cation-anion redox, wherein the general formula of the high-entropy layered oxide material is Na a [Li b Mg c Ni d Mn e M f ]O 2+β It is represented as, Here, M represents a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W, a, b, c, d, e, f, and 2+β represent the mole fractions of the corresponding elements, and the relationships between a, b, c, d, e, f, and 2+β satisfy b+c+d+e+f=1 and a+b+2c+2d+4e+mf=2(2+β), where 0.85≦a≦1, 0.05≦b≦0.2, 0.05≦c≦0.2, 0.05≦d≦0.2, 0.2≦e≦0.6, 0.05≦f≦0.2, and 0≦β≦0.1, and m represents the oxidation state of M. a, b, c, d, e, f satisfy the definition of high entropy, that is, they satisfy the following equation:

number

number

number

[0109] (Note 2) A method for preparing a high-entropy layered oxide material having a cation-anion redox as described in Appendix 1, wherein the method is a solid-phase method. A precursor powder is obtained by proportionally mixing a sodium source material in a stoichiometric ratio of 100% to 108% of the required sodium, a lithium source material in a stoichiometric ratio of 100% to 108% of the required lithium, a magnesium source material in the required stoichiometric ratio, a nickel source material, a manganese source material, and a compound M, and then uniformly mixing them. The obtained precursor powder is placed in a crucible, heated in a high-temperature furnace under an air atmosphere, cooled, removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox. A preparation method characterized by including the following.

[0110] (Note 3) The aforementioned sodium source material is sodium carbonate. The lithium source material comprises lithium carbonate and / or lithium hydroxide. The magnesium source material includes magnesium oxide and / or magnesium carbonate. The aforementioned nickel source material is nickel oxide. The manganese source material is manganese dioxide and / or dimanganese trioxide. The compound M comprises an oxide and / or a carbonate of M, where M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The aforementioned method of uniform mixing is grinding and mixing or ball mill mixing. The aforementioned heat treatment specifically involves heat treatment at a temperature of 800°C to 1000°C for 2 to 24 hours. The preparation method described in Appendix 2, characterized by the features described herein.

[0111] (Note 4) A method for preparing a high-entropy layered oxide material having a cation-anion redox as described in Appendix 1, wherein the method is a sol-gel method. Dissolve 100% to 108% of the required sodium stoichiometric ratio of sodium source material, 100% to 108% of the required lithium-containing water-soluble salt or tetrabutyl titanate, and the required stoichiometric ratio of magnesium, nickel, manganese, and M-containing water-soluble salt or tetrabutyl titanate in a solvent, and add citric acid to form a precursor gel. The precursor gel is placed in a crucible and then placed in a high-temperature furnace, where it is subjected to low-temperature pretreatment in an air atmosphere to obtain a pre-treated powder. The aforementioned pre-treated powder is subjected to high-temperature heat treatment in an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox. A preparation method characterized by including the following.

[0112] (Note 5) The aforementioned sodium source material is one or more of sodium acetate, sodium nitrate, sodium carbonate, and sodium sulfate. M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The solvent includes anhydrous ethanol or deionized water. The aforementioned low-temperature pretreatment specifically involves calcining at a temperature of 250°C to 500°C for 2 to 6 hours. The aforementioned high-temperature heat treatment specifically involves heat treatment at 800°C to 1000°C for 2 to 24 hours. The preparation method described in Appendix 4, characterized by the features described herein.

[0113] (Note 6) A method for preparing a high-entropy layered oxide material having a cation-anion redox as described in Appendix 1, wherein the method is a spray drying method. The process involves mixing a sodium source material in proportion to 100% to 108% of the required sodium stoichiometric ratio, a lithium source material in proportion to 100% to 108% of the required lithium stoichiometric ratio, a magnesium source material in the required stoichiometric ratio, a nickel source material, a manganese source material, and a compound M in proportion to obtain a precursor after uniform mixing. After adding a predetermined ratio of solvent to the precursor, a slurry is formed by uniformly stirring. The slurry is placed in a spray dryer and spray-dried to obtain a precursor powder. The precursor powder is placed in a crucible, placed in a high-temperature furnace, and heat-treated under an air atmosphere. The heat-treated precursor powder is pulverized to obtain the high-entropy layered oxide material, A preparation method characterized by including the following.

[0114] (Note 7) The aforementioned sodium source material is sodium carbonate. The lithium source material comprises lithium carbonate and / or lithium hydroxide. The magnesium source material includes magnesium oxide and / or magnesium carbonate. The aforementioned nickel source material is nickel oxide. The manganese source material is manganese dioxide and / or dimanganese trioxide. The compound M comprises an oxide and / or a carbonate of M, where M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The aforementioned method of uniform mixing is grinding and mixing or ball mill mixing. The solvent includes anhydrous ethanol or deionized water. The aforementioned heat treatment method specifically involves heat treatment at a temperature of 800°C to 1000°C for 2 to 24 hours. The inlet temperature of the spray dryer is 150°C to 190°C, the outlet temperature is 70°C to 100°C, and the supply rate is 200 mL / h to 600 mL / h. The preparation method described in Appendix 6, characterized by the features described herein.

[0115] (Note 8) A positive electrode plate for a sodium-ion secondary battery, characterized in that the positive electrode plate comprises a current collector, a conductive additive and adhesive coated on the current collector, and a high-entropy layered oxide material having the cation-anion redox described in Appendix 1 above.

[0116] (Note 9) A sodium-ion secondary battery characterized by comprising the positive electrode plate described in Appendix 8 above.

[0117] (Note 10) The use of the sodium-ion secondary battery described in Appendix 9 above, characterized in that the sodium-ion secondary battery is used in mobile devices, means of transportation, renewable energy generation, peak adjustment in smart grids, distributed power plants, backup power sources, or energy storage equipment for communication base stations.

Claims

1. A high-entropy layered oxide material having a cation-anion redox, wherein the general formula of the high-entropy layered oxide material is Na ａ [Li ｂ Mg ｃ Ni ｄ Mn ｅ M ｆ ]O ２＋β It is represented as, Here, M represents a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W, a, b, c, d, e, f, and 2+β represent the mole fractions of the corresponding elements, and the relationships between a, b, c, d, e, f, and 2+β satisfy b+c+d+e+f=1 and a+b+2c+2d+4e+mf=2(2+β), where 0.85≦a≦1, 0.05≦b≦0.2, 0.05≦c≦0.2, 0.05≦d≦0.2, 0.2≦e≦0.6, 0.05≦f≦0.2, and 0≦β≦0.1, and m represents the oxidation number of M. a, b, c, d, e, f satisfy the definition of high entropy, that is, they satisfy the following equation: [Math 1] However, R is the gas constant, and N ≥ 6. [Math 2] is one of the values ​​a, b, c, d, e, or f. The aforementioned high-entropy layered oxide material is an O3-type layered oxide material, and the space group is [Math 3] And, The aforementioned high-entropy layered oxide material is used as a positive electrode active material for sodium-ion secondary batteries. During the initial charging cycle, electrochemically active transition metal M ions first lose electrons, followed by oxygen ions in the crystal lattice, causing the average valency of oxygen ions to rise from -2 to between -2 and -1. During the initial discharge process, electrochemically active transition metal M ions and oxygen ions with high valencies regain electrons. In subsequent cycles, oxygen ions and electrochemically active transition metal M ions exchange electrons during the charging and discharging processes. A high-entropy layered oxide material having cation-anionic redox, characterized by the above.

2. A method for preparing a high-entropy layered oxide material having a cation-anion redox as described in claim 1, wherein the method is a solid-phase method. A precursor powder is obtained by mixing a sodium source material in proportion to 100% to 108% of the required sodium stoichiometric ratio, a lithium source material in proportion to 100% to 108% of the required lithium stoichiometric ratio, a magnesium source material in the required stoichiometric ratio, a nickel source material, a manganese source material, and a compound M in proportion to a uniform mixture. The obtained precursor powder is placed in a crucible, heated in a high-temperature furnace under an air atmosphere, cooled, removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox. A preparation method characterized by including the following.

3. The aforementioned sodium source material is sodium carbonate. The lithium source material includes lithium carbonate and / or lithium hydroxide. The magnesium source material includes magnesium oxide and / or magnesium carbonate. The aforementioned nickel source material is nickel oxide. The manganese source material is manganese dioxide and / or dimanganese trioxide. The compound M comprises an oxide and / or a carbonate of M, where M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The aforementioned method of uniform mixing is grinding and mixing or ball mill mixing. The aforementioned heat treatment specifically involves heat treatment at a temperature of 800°C to 1000°C for 2 to 24 hours. The preparation method according to claim 2, characterized in that

4. A method for preparing a high-entropy layered oxide material having a cation-anion redox as described in claim 1, wherein the method is a sol-gel method, Dissolve 100% to 108% of the required sodium stoichiometric ratio of sodium source material, 100% to 108% of the required lithium-containing water-soluble salt or tetrabutyl titanate, and the required stoichiometric ratio of magnesium, nickel, manganese, and M-containing water-soluble salt or tetrabutyl titanate in a solvent, and add citric acid to form a precursor gel. The precursor gel is placed in a crucible and then placed in a high-temperature furnace, where it is subjected to low-temperature pretreatment in an air atmosphere to obtain a pre-treated powder. The aforementioned pre-treated powder is subjected to high-temperature heat treatment in an air atmosphere, cooled and removed, and then pulverized to obtain a high-entropy layered oxide material having cation-anionic redox. A preparation method characterized by including the following.

5. The aforementioned sodium source material is one or more of sodium acetate, sodium nitrate, sodium carbonate, and sodium sulfate. M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The solvent includes anhydrous ethanol or deionized water. The aforementioned low-temperature pretreatment specifically involves calcining at a temperature of 250°C to 500°C for 2 to 6 hours. The aforementioned high-temperature heat treatment specifically involves heat treatment at 800°C to 1000°C for 2 to 24 hours. The preparation method according to claim 4, characterized in that

6. A method for preparing a high-entropy layered oxide material having a cation-anion redox as described in claim 1, wherein the method is a spray drying method, A precursor is obtained by mixing a sodium source material in proportion to 100% to 108% of the required sodium stoichiometric ratio, a lithium source material in proportion to 100% to 108% of the required lithium stoichiometric ratio, a magnesium source material in the required stoichiometric ratio, a nickel source material, a manganese source material, and a compound M in proportion to a uniform mixture. After adding a predetermined ratio of solvent to the precursor, a slurry is formed by uniformly stirring. The slurry is placed in a spray dryer and spray-dried to obtain a precursor powder. The precursor powder is placed in a crucible, placed in a high-temperature furnace, and heat-treated under an air atmosphere. The heat-treated precursor powder is pulverized to obtain the high-entropy layered oxide material, A preparation method characterized by including the following.

7. The aforementioned sodium source material is sodium carbonate. The lithium source material includes lithium carbonate and / or lithium hydroxide. The magnesium source material includes magnesium oxide and / or magnesium carbonate. The aforementioned nickel source material is nickel oxide. The manganese source material is manganese dioxide and / or dimanganese trioxide. The compound M comprises an oxide and / or a carbonate of M, where M is a transition metal element containing one or more elements from Cu, Fe, Zn, Nb, Mo, Ru, Sb, Ta, Bi, Ti, La, and W. The aforementioned method of uniform mixing is grinding and mixing or ball mill mixing. The solvent includes anhydrous ethanol or deionized water. The aforementioned heat treatment method specifically involves performing heat treatment at a temperature of 800°C to 1000°C for 2 to 24 hours. The inlet temperature of the spray dryer is 150°C to 190°C, the outlet temperature is 70°C to 100°C, and the supply rate is 200 mL / h to 600 mL / h. The preparation method according to claim 6, characterized in that

8. A positive electrode plate for a sodium-ion secondary battery, wherein the positive electrode plate comprises a current collector, a conductive additive and adhesive coated on the current collector, and a high-entropy layered oxide material having a cation-anion redox as described in claim 1.

9. A sodium-ion secondary battery characterized by comprising the positive electrode plate described in claim 8 above.

10. The use of the sodium-ion secondary battery according to claim 9 above, characterized in that the sodium-ion secondary battery is used in mobile devices, means of transportation, renewable energy generation, peak adjustment in smart grids, distributed power plants, backup power sources, or energy storage equipment for communication base stations.

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