A high-entropy layered oxide material and its preparation method and application

Abstract

The present invention discloses a high entropy layered oxide material and its preparation method and application. The general chemical formula of the material is: Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2‑a M a O2@Na 0.67 XO2, with Na as the core 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2‑a M a O2 material, with Na on the surface 0.67 XO2 material; M is one or more of zinc, copper, and aluminum; X is one or more of nickel, iron, manganese, and cobalt, where 0.05 ≤ a ≤ 0.1. The material is prepared using a solid-phase combined with a liquid-phase method. The high-entropy layered oxide material is used in sodium-ion secondary batteries. This invention effectively improves the structural stability of the material, thereby extending the cycle life of sodium-ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of battery energy materials, and in particular to a high-entropy layered oxide material and a preparation method and application thereof. Background Art

[0002] In recent years, sodium-ion batteries have received widespread attention as a new energy storage technology. Their working principle is similar to that of lithium-ion batteries, but they have significant advantages in material selection and cost-effectiveness. Unlike lithium-ion batteries, sodium-ion batteries can use aluminum foil as current collectors for the positive and negative electrodes. Therefore, sodium-ion batteries avoid the use of more expensive and heavier copper current collectors, thereby significantly reducing the overall cost of the battery and improving the energy density. The abundance of sodium in the earth's crust is much higher than that of lithium, which makes the supply of raw materials for sodium-ion batteries more stable and sustainable. In addition, the production process of sodium-ion batteries is relatively simple, which helps to achieve large-scale production and widespread application.

[0003] Compared with lithium-ion batteries, sodium-ion batteries still have a lot of room for improvement in actual capacity and cycle performance. Layered oxide positive electrode materials show poor stability when exposed to air. Specifically, the surface residual alkali is serious. Due to the embedding of water molecules in the air and the accelerating effect of carbon dioxide, residual alkaline substances are easily formed on the surface of the oxide positive electrode. These residual alkaline substances will further cause structural damage to the oxide positive electrode, leading to material failure. Lattice oxygen is prone to escape from the oxide positive electrode during the charge and discharge process. This phenomenon not only affects the structural integrity of the material, but may also lead to irreversible phase changes, thereby reducing the overall performance of the battery. In addition, the kinetic process of lattice oxygen in the layered oxide positive electrode is relatively slow, which further aggravates the decline in battery performance, especially cycle stability and rate performance. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing a high-entropy layered oxide material with high cycle performance and its application, which forms a uniform and stable Na 0.67 The XO2 interface protection layer utilizes the respective advantages of the P2 and O3 structures, thereby comprehensively enhancing the performance of the battery positive electrode material.

[0005] In the first aspect, the present invention provides a high entropy layered oxide material, the chemical formula of the high entropy layered oxide material is: Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2@Na 0.67 XO2, with Na as the core 0.9 Ni 0.2Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2 material, with Na on the surface 0.67 XO2 material; M is one or more elements selected from zinc, copper, and aluminum; X is one of nickel, iron, manganese, and cobalt; wherein 0.05≤a≤0.1;

[0006] The crystal structure of the high entropy layered oxide material is an O3 phase in the core, an R3m space group, and a P2 phase on the surface.

[0007] In a second aspect, the present invention provides a method for preparing the high-entropy layered oxide material as described in the first aspect above, wherein the method is a solid-phase method + liquid-phase method, comprising:

[0008] Mixing 90 wt% to 112 wt% of sodium carbonate with the required stoichiometric amount of nickel oxide, manganese oxide, iron oxide, titanium oxide, cobalt oxide and M oxide in the required stoichiometric proportion to form a precursor, wherein the M oxide is specifically one or more of zinc oxide, copper oxide and aluminum oxide;

[0009] The precursors are uniformly mixed by ball milling to obtain precursor powders, and the precursor powders are placed in a muffle furnace and heat-treated in an air atmosphere at 600°C to 1000°C for 5 to 25 hours; the heat-treated precursor powders are ground and sieved to obtain Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2 materials;

[0010] Weigh CHCOONa and X(CH3COO)2·4H2O and dissolve them in an organic solvent at a ratio of Na:X=0.67:1 to obtain solution A. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a Add O2 cathode material to solution A and stir for 30 minutes to ensure that Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a The O2 material is evenly dispersed to form suspension B;

[0011] Add an appropriate amount of oxalic acid solution dropwise to suspension B, stirring the generated Na2C2O4 and XC2O4 precipitates to completely cover the Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2 positive electrode material, forming a suspension C; the suspension C is dried, and the resulting powder is transferred to a muffle furnace, calcined at 800-1000 ° C for 5-10 hours in an air atmosphere, and finally the target material Na is obtained after natural cooling. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2@Na 0.67 XO2.

[0012] According to some embodiments of the present invention, the nickel oxide, manganese oxide, iron oxide, titanium oxide, and cobalt oxide are nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, and cobalt oxide, respectively.

[0013] According to some embodiments of the present invention, the oxide of M is zinc oxide.

[0014] According to some embodiments of the present invention, the organic solvent is anhydrous ethanol.

[0015] According to some embodiments of the present invention, the X(CH3COO)2·4H2O is Ni(CH3COO)2·4H2O.

[0016] In a third aspect, the high-entropy layered oxide material provided by the present invention is used for sodium ion secondary batteries, which are used for large-scale energy storage equipment such as solar power generation, heavy industry, backup mobile power supplies or communication base stations.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention utilizes a liquid phase method to coat a P2 phase material on the surface of a high entropy layered oxide. This structural design fully utilizes the advantages of both the P2 phase and the O3 phase. The P2 phase has excellent ion transport properties, while the O3 phase provides a higher capacity. The combination of the two significantly improves the overall electrochemical performance of the material.

[0019] (2) The present invention selects specific compound raw materials to prepare high-entropy layered oxide materials. These raw materials can form a uniform phase distribution during the high-temperature synthesis process, thereby ensuring the structural stability and high specific capacity of the material during the charge and discharge process;

[0020] (3) The present invention provides meaningful guidance for the preparation of sodium ion battery positive electrode materials with excellent electrochemical properties and their practical applications. Due to the stabilizing effect of the interface layer, the material has an initial coulombic efficiency of 98% and a retention rate of 88% after 300 cycles. At the same time, the rate and energy density are also significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The Na provided in Example 1 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 O2@Na 0.67 XRD pattern of NiO2.

[0022] Figure 2 The Na provided in Example 1 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 O2@Na 0.67 SEM image of NiO2.

[0023] Figure 3 The Na provided in Example 1 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 O2@Na 0.67 Cycling performance diagram of NiO2. DETAILED DESCRIPTION

[0024] In order to better understand the technical solution provided by the present invention, the following are several specific examples respectively illustrating the application of several methods provided by the present invention to prepare high entropy Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2@Na 0.67 Specific processes for XO2 layered oxide materials.

[0025] Example 1

[0026] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0027] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide, (the oxide of M is zinc oxide, and all raw materials are analytically pure) are mixed in the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.15 mol, cobalt oxide 0.2 mol, zinc oxide 0.05 mol), and ball milled on a ball mill at 400 rpm for 10 hours to obtain a precursor; the precursor mixture is transferred to an aluminum oxide crucible and treated at 900°C in a muffle furnace for 15 hours to obtain a black powder layered oxide material Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 O2;

[0028] Weigh 0.000335 mol CHCOONa (99.0%) and 0.0005 mol Ni(CH3COO)2·4H2O (99.0%), dissolve them in 200 mL of anhydrous ethanol (≥99.8%) at a ratio of Na:Ni=0.67:1, and stir vigorously for 30 minutes to ensure complete dissolution to obtain solution A; add 0.0245 mol Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 The O2 cathode material was added to solution A and stirred at 1000 r / min for 30 minutes to ensure that Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 The O2 material is evenly dispersed to form suspension B;

[0029] Anhydrous ethanol was used as the solvent to prepare a 0.005 mol oxalic acid solution. An appropriate amount of oxalic acid solution was added dropwise to suspension B and stirred at 1000 rpm for 100 minutes to ensure that the generated Na2C2O4 and NiC2O4 precipitates completely covered the Na 0.9 Ni 0.2Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 O2 positive electrode material, forming suspension C; placing suspension C in an oven at 120 ° C, evaporating the solvent for 8 hours, transferring the resulting powder to a muffle furnace, calcining it at 800 ° C for 10 hours in an air atmosphere, and finally obtaining the target material Na after natural cooling. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 O2@Na 0.67 NiO2, its XRD pattern is shown in Figure 1 , its SEM spectrum can be found in Figure 2 ;

[0030] The battery was assembled in an argon atmosphere glove box, with a sodium metal sheet as the negative electrode and NaPF6 (DMC:EC=1:1Vol%+5%FEC) as the electrolyte. The battery was assembled and the cycle performance was tested at a current density of 1 C. The test results are shown in Figure 3 , specific data are shown in Table 1.

[0031] Example 2

[0032] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0033] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide (the oxide M is zinc oxide, and all raw materials are analytical grade) are mixed in the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.15 mol, cobalt oxide 0.2 mol, zinc oxide 0.05 mol), and the high temperature solid phase method preparation process is the same as in Example 1;

[0034] Weigh 0.000335 mol CHCOONa (99.0%) and 0.0005 mol Fe(CH3COO)2·4H2O (99.0%), and dissolve them in 200 mL of anhydrous ethanol (≥99.8%) at a ratio of Na:Fe=0.67:1; the liquid phase preparation process is the same as in Example 1, and the target material Na is finally obtained. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 O2@Na0.67 FeO2;

[0035] The electrochemical test process was the same as in Example 1, and the specific data are shown in Table 1.

[0036] Example 3

[0037] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0038] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide (the oxide M is zinc oxide, and all raw materials are analytical grade) are mixed in the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.15 mol, cobalt oxide 0.2 mol, zinc oxide 0.05 mol), and the high temperature solid phase method preparation process is the same as in Example 1;

[0039] Weigh 0.000335 mol CHCOONa (99.0%) and 0.0005 mol Mn(CH3COO)2·4H2O (99.0%), and dissolve them in 200 mL of anhydrous ethanol (≥99.8%) at a ratio of Na:Mn=0.67:1; the liquid phase preparation process is the same as in Example 1, and the target material Na is finally obtained. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 O2@Na 0.67 MnO2;

[0040] The electrochemical test process was the same as in Example 1, and the specific data are shown in Table 1.

[0041] Example 4

[0042] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0043] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide (the oxide M is zinc oxide, and all raw materials are analytical grade) are mixed in the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.15 mol, cobalt oxide 0.2 mol, zinc oxide 0.05 mol), and the high temperature solid phase method preparation process is the same as in Example 1;

[0044] Weigh 0.000335 mol CHCOONa (99.0%) and 0.0005 mol Co(CH3COO)2·4H2O (99.0%), and dissolve them in 200 mL of anhydrous ethanol (≥99.8%) at a ratio of Na:Co=0.67:1; the liquid phase preparation process is the same as in Example 1, and the target material Na is finally obtained. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 O2@Na 0.67 CoO2;

[0045] The electrochemical test process was the same as in Example 1, and the specific data are shown in Table 1.

[0046] Example 5

[0047] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0048] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide (the oxide of M is copper oxide, and all raw materials are analytical grade) are mixed in the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.15 mol, cobalt oxide 0.2 mol, copper oxide 0.05 mol), and the high temperature solid phase method preparation process is the same as in Example 1;

[0049] Weigh 0.000335 mol CHCOONa (99.0%) and 0.0005 mol Ni(CH3COO)2·4H2O (99.0%), and dissolve them in 200 mL of anhydrous ethanol (≥99.8%) at a ratio of Na:Ni=0.67:1; the liquid phase preparation process is the same as in Example 1, and the target material Na is finally obtained. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Cu 0.05 O2@Na 0.67 NiO2;

[0050] The electrochemical test process was the same as in Example 1, and the specific data are shown in Table 1.

[0051] Example 6

[0052] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0053] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide, (the oxide M is aluminum oxide, and all raw materials are analytical grade) are mixed in the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.15 mol, cobalt oxide 0.2 mol, aluminum oxide 0.05 mol), and the high temperature solid phase method preparation process is the same as in Example 1;

[0054] Weigh 0.000335 mol CHCOONa (99.0%) and 0.0005 mol Ni(CH3COO)2·4H2O (99.0%), and dissolve them in 200 mL of anhydrous ethanol (≥99.8%) at a ratio of Na:Ni=0.67:1; the liquid phase preparation process is the same as in Example 1, and the target material Na is finally obtained. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Al 0.05 O2@Na 0.67 NiO2;

[0055] The electrochemical test process was the same as in Example 1, and the specific data are shown in Table 1.

[0056] Example 7

[0057] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0058] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide (M oxide is copper oxide + zinc oxide, all raw materials are analytical grade) are mixed in the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.1 mol, cobalt oxide 0.2 mol, zinc oxide 0.05 mol, copper oxide 0.05 mol), and the high temperature solid phase method preparation process is the same as in Example 1;

[0059] Weigh 0.000335 mol CHCOONa (99.0%) and 0.0005 mol Ni(CH3COO)2·4H2O (99.0%), and dissolve them in 200 mL of anhydrous ethanol (≥99.8%) at a ratio of Na:Ni=0.67:1; the liquid phase preparation process is the same as in Example 1, and the target material Na is finally obtained. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.1Cu 0.05 Zn 0.05 O2@Na 0.67 NiO2;

[0060] The electrochemical test process was the same as in Example 1, and the specific data are shown in Table 1.

[0061] Example 8

[0062] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0063] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide (the oxide M is aluminum oxide + zinc oxide, and all raw materials are analytical grade) are mixed in the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.1 mol, cobalt oxide 0.2 mol, zinc oxide 0.05 mol, aluminum oxide 0.05 mol), and the high temperature solid phase method preparation process is the same as in Example 1;

[0064] Weigh 0.000335 mol CHCOONa (99.0%) and 0.0005 mol Ni(CH3COO)2·4H2O (99.0%), and dissolve them in 200 mL of anhydrous ethanol (≥99.8%) at a ratio of Na:Ni=0.67:1; the liquid phase preparation process is the same as in Example 1, and the target material Na is finally obtained. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.1 Zn 0.05 Al 0.05 O2@Na 0.67 NiO2;

[0065] The electrochemical test process was the same as in Example 1, and the specific data are shown in Table 1.

[0066] Comparative Example 1

[0067] In this comparative example, a high-temperature solid-phase method is used to prepare a layered oxide material, including:

[0068] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide, (the oxide of M is zinc oxide, and all raw materials are analytically pure) are mixed in the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.15 mol, cobalt oxide 0.2 mol, zinc oxide 0.05 mol), and ball milled on a ball mill at 400 rpm for 10 hours to obtain a precursor; the precursor mixture is transferred to an aluminum oxide crucible and treated at 900°C in a muffle furnace for 15 hours to obtain a black powder layered oxide material Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Zn 0.05 Finally, the high-entropy layered oxide material prepared above was used as the active material for the positive electrode material of a sodium-ion battery and subjected to electrochemical cycling performance testing. The test data are shown in Table 1.

[0069] Comparative Example 2

[0070] In this comparative example, a high-temperature solid-phase method is used to prepare a layered oxide material, including:

[0071] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide, (the oxide of M is copper oxide, and all raw materials are analytically pure) are mixed according to the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.15 mol, cobalt oxide 0.2 mol, copper oxide 0.05 mol), and the preparation process is the same as that of Comparative Example 1 to obtain a black powder layered oxide material Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Cu 0.0 5O2; Finally, the high entropy layered oxide material prepared above was used as the active material of the battery positive electrode material for the preparation of sodium ion battery, and the electrochemical cycle performance test was carried out. The electrochemical test process was the same as that of Example 1, and the test data are shown in Table 1.

[0072] Comparative Example 3

[0073] In this comparative example, a high-temperature solid-phase method is used to prepare a layered oxide material, including:

[0074] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide, (the oxide of M is aluminum oxide, and all raw materials are analytically pure) are mixed according to the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.15 mol, cobalt oxide 0.2 mol, aluminum oxide 0.05 mol). The preparation process is the same as that of Comparative Example 1 to obtain a black powder layered oxide material Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.15 Al 0.05 Finally, the high-entropy layered oxide material prepared above was used as the active material of the battery positive electrode material for the preparation of a sodium ion battery, and the electrochemical cycle performance test was performed. The electrochemical test process was the same as in Example 1, and the test data is shown in Table 1.

[0075] Comparative Example 4

[0076] In this embodiment, a high-entropy layered oxide material is prepared by a high-temperature solid-phase method, including:

[0077] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide, (the oxide of M is copper oxide + zinc oxide, and the raw materials are all analytically pure) are mixed according to the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.1 mol, cobalt oxide 0.2 mol, zinc oxide 0.05 mol, copper oxide 0.05 mol). The preparation process is the same as that of Comparative Example 1 to obtain a black powder layered oxide material Na 0.9 Ni 0.2 Fe 0. 2Mn 0.2 Co 0.2 Ti 0.1 Zn 0.05 Cu 0.05 Finally, the high-entropy layered oxide material prepared above was used as the active material of the battery positive electrode material for the preparation of a sodium ion battery, and the electrochemical cycle performance test was performed. The electrochemical test process was the same as in Example 1, and the test data is shown in Table 1.

[0078] Comparative Example 5

[0079] In this comparative example, a high-temperature solid-phase method is used to prepare a layered oxide material, including:

[0080] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, titanium dioxide, cobalt oxide, (the oxide of M is aluminum oxide + zinc oxide, and all raw materials are analytically pure) are mixed according to the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.2 mol, manganese dioxide 0.2 mol, ferric oxide 0.2 mol, titanium dioxide 0.1 mol, cobalt oxide 0.2 mol, zinc oxide 0.05 mol, aluminum oxide 0.05 mol). The preparation process is the same as that of Comparative Example 1 to obtain a black powder layered oxide material Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.1 Zn 0.05 Al 0.05 Finally, the high-entropy layered oxide material prepared above was used as the active material of the battery positive electrode material for the preparation of a sodium ion battery, and the electrochemical cycle performance test was performed. The electrochemical test process was the same as in Example 1, and the test data is shown in Table 1.

[0081] Comparative Example 6

[0082] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0083] Sodium carbonate, nickel oxide, manganese dioxide, and ferric oxide (all raw materials are analytical grade) are mixed according to the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.333 mol, manganese dioxide 0.333 mol, ferric oxide 0.333 mol). The preparation process is the same as in Example 1, and the target material Na 0.9 Ni 1 / 3 Fe 1 / 3 Mn 1 / 3 O2@Na 0.67 Finally, the high-entropy layered oxide material prepared above was used as the active material of the battery positive electrode material for the preparation of a sodium ion battery, and the electrochemical cycle performance test was carried out. The electrochemical test process was the same as in Example 1, and the test data are shown in Table 1.

[0084] Comparative Example 7

[0085] In this embodiment, a high-entropy layered oxide material is prepared using a high-temperature solid-phase method + liquid-phase method, including:

[0086] Sodium carbonate, nickel oxide, manganese dioxide, ferric oxide, and titanium dioxide (all raw materials are analytical grade) are mixed according to the required stoichiometric ratio (sodium carbonate 0.95 mol, nickel oxide 0.25 mol, manganese dioxide 0.25 mol, ferric oxide 0.25 mol, titanium dioxide 0.25 mol). The preparation process is the same as in Example 1, and the target material Na is finally obtained.0.9 Ni 1 / 4 Fe 1 / 4 Mn 1 / 4 Ti 1 / 4 O2@Na 0.67 Finally, the high-entropy layered oxide material prepared above was used as the active material of the battery positive electrode material for the preparation of a sodium ion battery, and the electrochemical cycle performance test was carried out. The electrochemical test process was the same as in Example 1, and the test data are shown in Table 1.

[0087] The following table shows the discharge test results of various embodiments and comparative examples.

[0088] Table 1 Charge and discharge test results of various embodiments and comparative examples.

[0089] The surface P2 phase material has better Na + The high-entropy layered oxide material has excellent diffusion dynamics and relatively low sodium content, and has better air stability and cycle performance than O3 phase materials. Therefore, the sodium ion secondary battery using the high-entropy layered oxide material of the present invention has good cycle performance, good safety performance, high average discharge voltage, and great practical potential, providing new ideas and references for sodium ion battery positive electrode materials.

[0090] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high entropy layered oxide material, characterized in that: The general chemical formula of the high entropy layered oxide material is: Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2@Na 0.67 XO2, with Na as the core 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2 material, with Na on the surface 0.67 XO2 material; M is one of zinc, copper, and aluminum; X is one of nickel, iron, manganese, and cobalt; wherein 0.05≤a≤0.1; The high entropy layered oxide material preparation method is a solid phase method + liquid phase method, comprising: Mixing sodium carbonate having a stoichiometric amount of 90 wt% to 112 wt% of the required sodium and a stoichiometric amount of nickel oxide, manganese oxide, iron oxide, titanium oxide, cobalt oxide and M oxide in a required proportion to form a precursor, wherein the M oxide is specifically one of zinc oxide, copper oxide and aluminum oxide; The precursors are uniformly mixed by ball milling to obtain precursor powders, and the precursor powders are placed in a muffle furnace and heat-treated in an air atmosphere at 600°C to 1000°C for 5 to 25 hours; the heat-treated precursor powders are ground and sieved to obtain Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2 materials; Weigh CHCOONa and X(CH3COO)2·4H2O and dissolve them in an organic solvent at a ratio of Na:X=0.67:1 to obtain solution A. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a Add O2 cathode material to solution A and stir for 30 minutes to ensure that Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a The O2 material is evenly dispersed to form suspension B; Add an appropriate amount of oxalic acid solution dropwise to suspension B, stirring the generated Na2C2O4 and XC2O4 precipitates to completely cover the Na 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2 positive electrode material, forming a suspension C; the suspension C is dried, and the resulting powder is transferred to a muffle furnace, calcined at 800-1000 ° C for 5-10 hours in an air atmosphere, and finally the target material Na is obtained after natural cooling. 0.9 Ni 0.2 Fe 0.2 Mn 0.2 Co 0.2 Ti 0.2-a M a O2@Na 0.67 XO2.

2. The high entropy layered oxide material according to claim 1, characterized in that The nickel oxide, manganese oxide, iron oxide, titanium oxide and cobalt oxide are nickel oxide, manganese dioxide, ferric oxide, titanium dioxide and cobalt oxide respectively.

3. The high entropy layered oxide material according to claim 1, characterized in that The organic solvent is anhydrous ethanol.

4. The high entropy layered oxide material according to claim 1, characterized in that The high entropy layered oxide material is used for sodium ion secondary batteries.

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