Positive electrode material and preparation method thereof

Abstract

The invention relates to the technical field of positive electrode materials, and particularly discloses a positive electrode material and a preparation method thereof. The positive electrode material provided by the invention comprises a base material and an AB2O4 coating layer coating the surface of the base material, and A and B are respectively and independently selected from at least one of Mg, Al, La, Y, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Sb, Ca or Ce; a comprises at least one of Mg or Ca, and B comprises at least one of La, Y or Ce; the AB2O4 coating layer is prepared by a molten salt method. According to the positive electrode material provided by the invention, by optimizing the structure of the coating layer on the surface of the base material and the preparation method of the coating layer, the technical problem that the existing coating layer cannot give consideration to high ionic conductivity, high structural stability and strong interface bonding force is solved, and the capacity and cycling stability of the sodium ion battery are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of cathode material technology, and in particular to a cathode material and its preparation method. Background Technology

[0002] Sodium's abundant resources and low cost have made sodium-ion batteries a promising candidate for large-scale energy storage. Layered oxide cathode materials for sodium-ion batteries are among the most promising cathode materials due to their high specific capacity and diverse structures. However, during storage, layered oxide cathodes readily react with CO2 / H2O in the air to form residual alkali on their surface. During charge and discharge, the cathode material comes into direct contact with the electrolyte, leading to side reactions that destabilize the electrolytic interface (CEI), dissolve transition metal ions, and cause capacity decay. Furthermore, under high voltage conditions, the cathode material undergoes complex phase transitions and lattice oxygen loss, resulting in structural collapse and deteriorated cycle performance.

[0003] To address the aforementioned issues, researchers employed a coating modification strategy, coating the surface of cathode materials with oxides such as TiO2, Al2O3, and ZrO2. These are mostly electrochemically inert single oxides. While these coatings can, to some extent, prevent direct contact between the electrolyte or air and the cathode particles, suppressing side reactions, they also hinder sodium ion diffusion, leading to increased internal resistance and decreased rate performance. Furthermore, single-component coatings negatively impact the battery's mechanical properties and chemical stability, making it prone to cracking and failure under high voltage and long-cycle conditions. Therefore, a cathode material and its preparation method are needed to overcome the technical challenge of existing cathode material coatings failing to simultaneously achieve high ionic conductivity, high structural stability, and strong interfacial adhesion. Summary of the Invention

[0004] In view of this, the present invention provides a cathode material and a method for preparing the same. The cathode material provided by the present invention solves the technical problem that existing coatings cannot simultaneously achieve high ionic conductivity, high structural stability, and strong interfacial bonding by optimizing the coating layer on the surface of the substrate material, thus greatly improving the capacity and cycle stability of sodium-ion batteries.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: The present invention provides a positive electrode material, comprising a matrix material and an AB2O4 coating layer covering the surface of the matrix material, wherein A and B are each independently selected from at least one of Mg, Al, La, Y, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Sb, Ca or Ce; A includes at least one of Mg or Ca, and B includes at least one of La, Y or Ce; The AB2O4 coating layer was prepared by the molten salt method.

[0006] In recent years, high-entropy oxide-coated matrix materials have been proposed to improve battery performance. However, most existing high-entropy oxide coatings are rock salt structures or amorphous structures. Their crystal structures themselves lack long-range ordered three-dimensional channels for fast ion transport, which essentially fails to solve the key bottleneck of low ion conductivity. They may even introduce additional ion migration barriers due to the disorder of the structure.

[0007] The cathode material provided by this invention uses AB2O4 high-entropy oxide with a spinel structure as a coating layer, and further determines the specific elements of the AB2O4 high-entropy oxide. Among them, A includes Mg or Ca with small ionic radius and moderate electronegativity, and B includes La, Y or Ce with large ionic radius and high oxygen affinity. The introduction of Mg or Ca can stabilize the spinel framework, while high-valence, large-radius ions such as La, Y or Ce can effectively suppress the loss of lattice oxygen under high voltage, thus jointly enhancing the structural integrity of the coating layer. The specific AB2O4 high-entropy oxide provided by this invention is a framework structure with a three-dimensional ion diffusion channel, which provides an ideal path for the rapid migration of sodium ions. When it is prepared on the cathode material as a coating layer by a specific molten salt method, it can significantly improve the ionic conductivity of the cathode material and overcome the defects of traditional inert coating layers or unstructured high-entropy oxide coating layers that hinder ion diffusion.

[0008] Preferably, A and B are selected from any 5 to 8 different elements selected from Mg, Al, La, Y, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Sb, Ca, or Ce.

[0009] Preferably, the matrix material is NaNi. 0.25 Fe 0.25 Mn 0.5 O2.

[0010] This invention provides a method for preparing the above-mentioned cathode material, comprising the following steps: S1. Preparation of matrix material; S2. Mix the precursor of A, the precursor of B, the matrix material and the molten salt evenly, and react at 600~800℃ to obtain the cathode material.

[0011] Currently, most existing high-entropy oxide coating technologies employ solid-phase or solution methods, which make it difficult to form a uniform, dense, and firmly bonded coating layer on the surface of layered oxides. Furthermore, these technologies often require high-temperature treatment, which can easily lead to damage to the substrate structure.

[0012] The method for preparing the cathode material provided by this invention involves a molten salt method and a reaction at a specific temperature to form a high-entropy coating layer with a spinel structure on the surface of the substrate material, which can effectively avoid structural damage to the substrate material. More importantly, the molten salt, as a medium, greatly promotes atomic or ion exchange between the coating layer precursor and the surface of the cathode substrate material, thereby forming a strong chemical bond at the interface. The chemical bond even grows epitaxially, effectively preventing the coating layer from peeling off during long-term cycling. This method solves the problems of low ionic conductivity, low structural stability, and poor interfacial bonding of existing cathode material coating layers. When used in sodium-ion batteries, it significantly improves the problems of low specific capacity and poor cycle stability of existing sodium-ion batteries.

[0013] Preferably, in step S1, the specific steps for the matrix material include the following: Step 1: Add sodium source, nickel source, iron source and manganese source to alcohol solvent and grind to obtain mixed slurry; Step 2: Dry and calcine the mixed slurry to obtain NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix material.

[0014] For example, in step 1, the sodium source includes at least one of sodium carbonate, sodium bicarbonate, sodium nitrate, sodium hydroxide, or sodium acetate; the nickel source includes at least one of nickel acetate, nickel nitrate, nickel chloride, or nickel hydroxide; the iron source includes at least one of ferric nitrate, ferric acetate, or ferric sulfate; and the manganese source includes at least one of manganese acetate, manganese nitrate, or manganese sulfate.

[0015] Preferably, in step 1, the alcohol solvent is anhydrous ethanol.

[0016] For example, in step 1, the amount of alcohol solvent added is no longer limited, and the amount added can be the amount known to those skilled in the art.

[0017] For example, in step 1, the grinding is performed by wet grinding on a high-energy ball mill. The specific grinding conditions are not further limited here; it is sufficient to mix the above raw materials evenly.

[0018] Preferably, in step 2, the drying conditions are: drying at 50~80℃ for 10~15 hours.

[0019] Preferably, in step 2, after the drying is completed, the dried material is ground evenly.

[0020] Preferably, in step 2, the calcination temperature is 850~950℃.

[0021] Further preferably, the temperature is increased to 850-950°C at a rate of 3-8°C / min.

[0022] Preferably, in step 2, the calcination time is 12-18 hours.

[0023] For example, in step 2, after calcination, the powder is cooled to room temperature in the furnace and then ground until it is a uniform powder without any grainy texture, thus obtaining the NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix material.

[0024] Preferably, in S2, the molten salt includes sodium chloride and potassium chloride.

[0025] More preferably, in S2, the molten salt comprises sodium chloride and potassium chloride in a molar ratio of 2:3 to 3:2.

[0026] The preferred molten salt composition can ensure that the metal source migrates in the molten salt medium and reacts on the surface of the matrix material, generating a high-entropy spinel coating layer in situ, thereby improving the performance of the battery.

[0027] Preferably, in S2, the total amount of the precursor of A and the precursor of B added is 1% to 5% of the mass of the matrix material.

[0028] It should be further noted that, in S2, the precursors of A and B are selected from at least one of the nitrates or acetates of the corresponding metals.

[0029] Preferably, in S2, the mass ratio of the molten salt to the matrix material is 1:1 to 3:1.

[0030] By further limiting the amount of molten salt used, the performance of the battery can be further improved.

[0031] Preferably, in S2, the reaction time is 8-12 hours.

[0032] Preferably, in S2, a programmed temperature rise method is used, with the temperature increased to 600~800℃ at a rate of 5℃ / min.

[0033] The method for preparing cathode material provided by the present invention constructs a high-entropy spinel structure coating layer on the surface of a substrate material by means of molten salt method. The cathode material prepared can be applied to sodium-ion batteries and can significantly improve the electrochemical performance of sodium-ion batteries. Attached Figure Description

[0034] Figure 1 This is a TEM image of the positive electrode material prepared in Example 1 of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] Example 1 This embodiment provides a method for preparing a cathode material, including the following steps: S1. Sodium nitrate, nickel nitrate, ferric nitrate and manganese nitrate are added to anhydrous ethanol and wet-milled to obtain a mixed slurry; S2. The mixed slurry is dried at 50°C for 15 hours, then calcined at 900°C for 15 hours at a rate of 5°C / min. After cooling in the furnace, it is ground into a uniform powder without any granules to obtain NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix materials; S3. Weigh out the magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, lanthanum nitrate, and NaNi. 0.25 Fe 0.25 Mn 0.5 The O2 matrix material and molten salt were mixed and ground thoroughly in a mortar for 1 hour. The mixture was then placed in a muffle furnace and heated to 700°C at 5°C / min for 10 hours to obtain the positive electrode material, denoted as Mg(AlCrFeCoLa)2O4@NaNi. 0.2 5Fe 0.25 Mn 0.5 O2; The total amount of magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, and lanthanum nitrate added is NaNi. 0.25 Fe 0.25 Mn 0.5 1% of the mass of the O2 matrix material; molten salt and NaNi 0.25 Fe 0.25 Mn 0.5 The mass ratio of the O2 matrix material is 2:1; the molten salt consists of sodium chloride and potassium chloride in a molar ratio of 1:1.

[0037] Example 2 This embodiment provides a method for preparing a cathode material, including the following steps: S1. Sodium nitrate, nickel nitrate, ferric nitrate and manganese nitrate are added to anhydrous ethanol and wet-milled to obtain a mixed slurry; S2. The mixed slurry is dried at 50°C for 15 hours, then calcined at 900°C for 15 hours at a rate of 5°C / min. After cooling in the furnace, it is ground into a uniform powder without any granules to obtain NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix materials; S3. Weigh out the magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, cerium nitrate, and NaNi. 0.25 Fe 0.25 Mn 0.5 The O2 matrix material and molten salt were mixed and ground thoroughly in a mortar for 1 hour. The mixture was then placed in a muffle furnace and heated to 700°C at 5°C / min for 10 hours to obtain the positive electrode material, denoted as Mg(AlCrFeCoCe)2O4@NaNi. 0.2 5Fe 0.25 Mn 0.5 O2; The total amount of magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, and cerium nitrate added is NaNi 0.25 Fe 0.25 Mn 0.5 3% of the mass of the O2 matrix material; molten salt and NaNi 0.25 Fe 0.25 Mn 0.5 The mass ratio of the O2 matrix material is 1:1; the molten salt includes sodium chloride and potassium chloride in a molar ratio of 2:3.

[0038] Example 3 This embodiment provides a method for preparing a cathode material, including the following steps: S1. Sodium nitrate, nickel nitrate, ferric nitrate and manganese nitrate are added to anhydrous ethanol and wet-milled to obtain a mixed slurry; S2. The mixed slurry is dried at 50°C for 15 hours, then calcined at 900°C for 15 hours at a rate of 5°C / min. After cooling in the furnace, it is ground into a uniform powder without any granules to obtain NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix materials; S3. Weigh out the following: magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, nickel nitrate, cobalt nitrate, lanthanum nitrate, and NaNi. 0.25 Fe 0.25 Mn 0.5 The O2 matrix material and molten salt were mixed and ground thoroughly in a mortar for 1 hour. The mixture was then placed in a muffle furnace and heated to 600°C at 5°C / min for 12 hours to obtain the positive electrode material, denoted as Mg(AlCrFeNiCoLa)2O4@NaNi. 0.2 5Fe 0.25 Mn 0.5 O2; The total amount of magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, nickel nitrate, cobalt nitrate, and lanthanum nitrate added is NaNi 0.25 Fe 0.25 Mn 0.55% of the mass of the O2 matrix material; molten salt and NaNi 0.25 Fe 0.25 Mn 0.5 The mass ratio of the O2 matrix material is 2:1; the molten salt consists of sodium chloride and potassium chloride in a molar ratio of 3:2.

[0039] Example 4 This embodiment provides a method for preparing a cathode material, including the following steps: S1. Sodium nitrate, nickel nitrate, ferric nitrate and manganese nitrate are added to anhydrous ethanol and wet-milled to obtain a mixed slurry; S2. The mixed slurry is dried at 50°C for 15 hours, then calcined at 900°C for 15 hours at a rate of 5°C / min. After cooling in the furnace, it is ground into a uniform powder without any granules to obtain NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix materials; S3. Weigh out the magnesium nitrate, aluminum nitrate, chromium nitrate, yttrium nitrate, nickel nitrate, lanthanum nitrate, and NaNi. 0.25 Fe 0.25 Mn 0.5 The O2 matrix material and molten salt were mixed and ground thoroughly in a mortar for 1 hour. The mixture was then placed in a muffle furnace and heated to 800°C at 5°C / min for 8 hours to obtain the positive electrode material, denoted as Mg(AlCrYNiLa)2O4@NaNi. 0.2 5Fe 0.25 Mn 0.5 O2; The total amount of magnesium nitrate, aluminum nitrate, chromium nitrate, yttrium nitrate, nickel nitrate, and lanthanum nitrate added is NaNi 0.25 Fe 0.25 Mn 0.5 3% of the mass of the O2 matrix material; molten salt and NaNi 0.25 Fe 0.25 Mn 0.5 The mass ratio of the O2 matrix material is 2:1; the molten salt consists of sodium chloride and potassium chloride in a molar ratio of 3:2.

[0040] Example 5 This embodiment provides a method for preparing a cathode material, including the following steps: S1. Sodium nitrate, nickel nitrate, ferric nitrate and manganese nitrate are added to anhydrous ethanol and wet-milled to obtain a mixed slurry; S2. The mixed slurry is dried at 50°C for 15 hours, then calcined at 900°C for 15 hours at a rate of 5°C / min. After cooling in the furnace, it is ground into a uniform powder without any granules to obtain NaNi. 0.25 Fe 0.25 Mn 0.5O2 matrix materials; S3. Weigh out the following: calcium nitrate, aluminum nitrate, chromium nitrate, yttrium nitrate, nickel nitrate, lanthanum nitrate, and NaNi. 0.25 Fe 0.25 Mn 0.5 The O2 matrix material and molten salt were mixed and ground thoroughly in a mortar for 1 hour. The mixture was then placed in a muffle furnace and heated to 800°C at 5°C / min for 8 hours to obtain the positive electrode material, denoted as Ca(AlCrYNiLa)2O4@NaNi. 0.2 5Fe 0.25 Mn 0.5 O2; The total amount of calcium nitrate, aluminum nitrate, chromium nitrate, yttrium nitrate, nickel nitrate, and lanthanum nitrate added is NaNi 0.25 Fe 0.25 Mn 0.5 3% of the mass of the O2 matrix material; molten salt and NaNi 0.25 Fe 0.25 Mn 0.5 The mass ratio of the O2 matrix material is 2:1; the molten salt consists of sodium chloride and potassium chloride in a molar ratio of 3:2.

[0041] Comparative Example 1 This comparative example provides a method for preparing a cathode material, which differs from Example 1 in that the resulting coating layer is a common high-entropy oxide coating layer, specifically including the following steps: S1. Sodium nitrate, nickel nitrate, ferric nitrate and manganese nitrate are added to anhydrous ethanol and wet-milled to obtain a mixed slurry; S2. The mixed slurry is dried at 50°C for 15 hours, then calcined at 900°C for 15 hours at a rate of 5°C / min. After cooling in the furnace, it is ground into a uniform powder without any granules to obtain NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix materials; S3. Weigh out the magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, lanthanum nitrate, and NaNi. 0.25 Fe 0.25 Mn 0.5 The O2 matrix material and molten salt were mixed and ground thoroughly in a mortar for 1 hour. The mixture was then placed in a muffle furnace and heated to 700°C at 5°C / min for 10 hours to obtain the positive electrode material, denoted as Mg. 1 / 6 Al 1 / 6 Cr 1 / 6 Fe 1 / 6 Co 1 / 6 La 1 / 6 O@NaNi 0.2 5Fe 0.25 Mn 0.5 O2; The total amount of magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, and lanthanum nitrate added is NaNi. 0.25 Fe 0.25 Mn 0.5 The amount of O2 matrix material is 1% of its mass, and the amounts of magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, and lanthanum nitrate are the same; molten salt and NaNi 0.25 Fe 0.25 Mn 0.5 The mass ratio of the O2 matrix material is 2:1; the molten salt consists of sodium chloride and potassium chloride in a molar ratio of 1:1.

[0042] Comparative Example 2 This comparative example provides a method for preparing a cathode material, which differs from Example 1 in that it does not add molten salt, and includes the following steps: S1. Sodium nitrate, nickel nitrate, ferric nitrate and manganese nitrate are added to anhydrous ethanol and wet-milled to obtain a mixed slurry; S2. The mixed slurry is dried at 50°C for 15 hours, then calcined at 900°C for 15 hours at a rate of 5°C / min. After cooling in the furnace, it is ground into a uniform powder without any granules to obtain NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix materials; S3. Weigh out the magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, lanthanum nitrate, and NaNi. 0.25 Fe 0.25 Mn 0.5 The O2 matrix material was mixed and ground thoroughly in a mortar for 1 hour. The mixture was then placed in a muffle furnace and heated to 700°C at 5°C / min for 10 hours to obtain the positive electrode material, denoted as Mg(AlCrFeCoLa)2O4@NaNi. 0.2 5Fe 0.25 Mn 0.5 O2; The total amount of magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, and lanthanum nitrate added is NaNi. 0.25 Fe 0.25 Mn 0.5 1% of the mass of the O2 matrix material.

[0043] Comparative Example 3 This comparative example provides a method for preparing a cathode material, including the following steps: S1. Sodium nitrate, nickel nitrate, ferric nitrate and manganese nitrate are added to anhydrous ethanol and wet-milled to obtain a mixed slurry; S2. The mixed slurry is dried at 50°C for 15 hours, then calcined at 900°C for 15 hours at a rate of 5°C / min. After cooling in the furnace, it is ground into a uniform powder without any granules to obtain NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix materials; S3. Weigh out the zinc nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, lanthanum nitrate, and NaNi. 0.25 Fe 0.25 Mn 0.5 The O2 matrix material and molten salt were mixed and ground thoroughly in a mortar for 1 hour. The mixture was then placed in a muffle furnace and heated to 700°C at 5°C / min for 10 hours to obtain the positive electrode material, denoted as Zn(AlCrFeCoLa)2O4@NaNi. 0.25 Fe 0.25 Mn 0.5 O2; The total amount of zinc nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, and lanthanum nitrate added is NaNi. 0.25 Fe 0.25 Mn 0.5 1% of the mass of the O2 matrix material; molten salt and NaNi 0.25 Fe 0.25 Mn 0.5 The mass ratio of the O2 matrix material is 2:1; the molten salt consists of sodium chloride and potassium chloride in a molar ratio of 1:1.

[0044] Comparative Example 4 This comparative example provides a method for preparing a cathode material, including the following steps: S1. Sodium nitrate, nickel nitrate, ferric nitrate and manganese nitrate are added to anhydrous ethanol and wet-milled to obtain a mixed slurry; S2. The mixed slurry is dried at 50°C for 15 hours, then calcined at 900°C for 15 hours at a rate of 5°C / min. After cooling in the furnace, it is ground into a uniform powder without any granules to obtain NaNi. 0.25 Fe 0.25 Mn 0.5 O2 matrix materials; S3. Weigh out the magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, manganese nitrate, and NaNi. 0.25 Fe 0.25 Mn 0.5 The O2 matrix material and molten salt were mixed and ground thoroughly in a mortar for 1 hour. The mixture was then placed in a muffle furnace and heated to 700°C at 5°C / min for 10 hours to obtain the positive electrode material, denoted as Mg(AlCrFeCoMn)2O4@NaNi. 0.2 5Fe 0.25 Mn 0.5O2; The total amount of magnesium nitrate, aluminum nitrate, chromium nitrate, ferric nitrate, cobalt nitrate, and manganese nitrate added is NaNi. 0.25 Fe 0.25 Mn 0.5 1% of the mass of the O2 matrix material; molten salt and NaNi 0.25 Fe 0.25 Mn 0.5 The mass ratio of the O2 matrix material is 2:1; the molten salt consists of sodium chloride and potassium chloride in a molar ratio of 1:1.

[0045] Example of effect The positive electrode materials prepared in Examples 1-5 and Comparative Examples 1-4 were coated with Super P and polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1 to prepare sodium-ion batteries. The sodium storage performance of the materials was studied by encapsulating CR2025 button cells with metallic sodium sheets as negative electrodes. Half-cell tests were conducted within a voltage window of 2-4.4V, and constant current charge / discharge measurements were performed using a LAND test instrument to test the capacity and cycle stability of the obtained sodium-ion batteries. The cycle test was first activated with a current density of 10 mA / g for two cycles, and then cycled for 100 cycles with a current density of 100 mA / g. The specific results are shown in Table 1.

[0046] Table 1

[0047] As shown in Table 1, the sodium-ion battery made using the cathode material provided in the embodiments of the present invention has excellent specific capacity, 5C discharge specific capacity and 100-cycle specific capacity. This further proves that the present invention solves the technical problem that existing coatings cannot simultaneously achieve high ionic conductivity, high structural stability and strong interfacial bonding by optimizing the coating layer on the surface of the cathode material, thereby greatly improving the capacity and cycle stability of sodium-ion batteries.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A positive electrode material, characterized in that, It includes a matrix material and an AB2O4 coating layer covering the surface of the matrix material, wherein A and B are each independently selected from at least one of Mg, Al, La, Y, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Sb, Ca or Ce; A includes at least one of Mg or Ca, and B includes at least one of La, Y or Ce; The AB2O4 coating layer was prepared by the molten salt method.

2. The cathode material as described in claim 1, characterized in that, A and B are selected from any 5 to 8 different elements selected from Mg, Al, La, Y, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Sb, Ca, or Ce.

3. The positive electrode material as described in claim 1, characterized in that, The matrix material is NaNi. 0.25 Fe 0.25 Mn 0.5 O2.

4. A method for preparing the cathode material according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Preparation of matrix material; S2. Mix the precursor of A, the precursor of B, the matrix material and the molten salt evenly, and react at 600~800℃ to obtain the cathode material.

5. The method for preparing the cathode material as described in claim 4, characterized in that, In S2, the molten salt includes sodium chloride and potassium chloride.

6. The method for preparing the cathode material as described in claim 5, characterized in that, In S2, the molten salt comprises sodium chloride and potassium chloride in a molar ratio of 2:3 to 3:

2.

7. The method for preparing the cathode material as described in claim 4, characterized in that, In S2, the total amount of precursors A and B added is 1% to 5% of the mass of the matrix material.

8. The method for preparing the cathode material as described in claim 4, characterized in that, In S2, the mass ratio of the molten salt to the matrix material is 1:1 to 3:

1.

9. The method for preparing the cathode material as described in claim 4, characterized in that, In S2, the reaction time is 8-12 hours.

10. The method for preparing the cathode material as described in claim 4, characterized in that, In S2, a programmed temperature rise method is used to raise the temperature to 600~800℃ at a rate of 5℃ / min.

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