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CN-121983503-A - Cooxidized carbon coated sodium vanadium fluorophosphate composite positive electrode material, preparation method thereof and sodium ion battery composite positive electrode

CN121983503ACN 121983503 ACN121983503 ACN 121983503ACN-121983503-A

Abstract

The invention relates to the field of battery field manufacturing, in particular to a co-oxidized carbon coated sodium vanadium fluorophosphate composite anode material, a preparation method thereof and a sodium ion battery composite anode, wherein the preparation method comprises the steps of adding a carbon source into mixed acid for reaction, then adding KMnO 4 for water bath reaction, finally adding hydrogen peroxide solution for co-oxidation reaction, and washing and drying after the reaction to obtain a co-oxidized carbon source; the carbon source is a mixture of a one-dimensional carbon source and a two-dimensional carbon source, the carbon source obtained in the step 1 is mixed and ground with a vanadium source, a sodium source, phosphate and a fluorine source to obtain precursor powder, the precursor powder is presintered to obtain a sodium vanadium fluorophosphate intermediate product, and the sodium vanadium fluorophosphate intermediate product is sintered at a high temperature to obtain the carbon co-oxide coated sodium vanadium fluorophosphate composite anode material. The positive electrode material prepared by the invention has high conductivity, high multiplying power, high discharge capacity, high power and good cycle stability, and can be used for preparing a sodium ion battery composite positive electrode.

Inventors

  • YUAN SONGDONG
  • FAN HUI

Assignees

  • 湖北工业大学

Dates

Publication Date
20260505
Application Date
20251229

Claims (10)

  1. 1. The preparation method of the co-oxidized carbon coated sodium vanadium fluorophosphate composite anode material is characterized by comprising the following steps of: Step1, adding a carbon source into mixed acid for reaction, then adding KMnO 4 for water bath reaction, finally adding hydrogen peroxide solution for co-oxidation reaction, and washing and drying after the reaction to obtain a co-oxidized carbon source, wherein the carbon source is a mixture of a one-dimensional carbon source and a two-dimensional carbon source; step 2, mixing and grinding the carbon dioxide source obtained in the step 1 with a vanadium source, a sodium source, phosphate and a fluorine source to obtain precursor powder, and presintering the precursor powder in a protective atmosphere at 300-400 ℃ for 4-6 hours to obtain a sodium vanadium fluorophosphate intermediate product; And 3, placing the intermediate product of the sodium vanadium fluorophosphate obtained in the step 2 in a protective atmosphere, and sintering at a high temperature of 550-800 ℃ for 6-10 hours to obtain the co-oxidized carbon coated sodium vanadium fluorophosphate composite anode material.
  2. 2. The method for preparing the co-oxidized carbon-coated sodium vanadium fluorophosphate composite anode material according to claim 1, wherein in the step 1, the one-dimensional carbon source is at least one of a carbon nanotube, a carbon nanofiber and a carbon nanowire, and the two-dimensional carbon source is at least one of graphene, mesophase carbon microsphere, acetylene black, crystalline flake graphite and porous carbon.
  3. 3. The method for preparing the co-oxidized carbon-coated sodium vanadium fluorophosphate composite anode material according to claim 1 or 2, wherein in the step 1, the mixing mass ratio of the one-dimensional carbon source to the two-dimensional carbon source is 1-3:1.
  4. 4. The method for preparing the co-oxidized carbon-coated sodium vanadium fluorophosphate composite anode material according to claim 1 or 2, wherein in the step 1, the reaction temperature of the carbon source and the mixed acid is 25-40 ℃ and the time is 20min, the mixed acid is any two mixtures of sulfuric acid, hydrochloric acid and nitric acid, and the addition amount of the carbon source is 2% of the mass of the mixed acid.
  5. 5. The method for preparing the co-oxidized carbon-coated sodium vanadium fluorophosphate composite anode material according to claim 1, wherein in the step 1, the adding amount of KMnO 4 is 1-1.2 times of the mass of the carbon source, and the water bath reaction temperature is 30-50 ℃ after adding KMnO 4 for 3-5 hours.
  6. 6. The method for preparing the co-oxidized carbon-coated sodium vanadium fluorophosphate composite anode material according to claim 1 or 5, wherein in the step 1, the hydrogen peroxide is added in an amount of 10% by mass of KMnO 4 , the co-oxidation reaction temperature is 35-40 ℃, and the time is 6-10 hours.
  7. 7. The method for preparing the co-oxidized carbon coated sodium vanadium fluorophosphate composite anode material according to claim 1, wherein in the step 2, the addition amount of the co-oxidized carbon source is 5% -30% of the total mass of the vanadium source, the sodium source, the phosphate and the fluorine source.
  8. 8. The method for preparing the co-oxidized carbon-coated sodium vanadium fluorophosphate composite cathode material according to claim 1 or 7, wherein in the step 2, the molar ratio of sodium element, vanadium element, phosphorus element and fluorine element in the vanadium source, sodium source, phosphate and fluorine source is 3:2:2:3.
  9. 9. The co-oxidized carbon-coated sodium vanadium fluorophosphate composite positive electrode material is characterized by being prepared by the preparation method of any one of claims 1-8.
  10. 10. A composite positive electrode of a sodium ion battery, which is characterized by comprising a substrate and a coating material on the surface of the substrate, wherein the coating material at least comprises the co-oxidized carbon coated sodium vanadium fluorophosphate composite positive electrode material, a conductive material and an adhesive.

Description

Cooxidized carbon coated sodium vanadium fluorophosphate composite positive electrode material, preparation method thereof and sodium ion battery composite positive electrode Technical Field The invention relates to the field of battery field manufacturing, in particular to a co-oxidized carbon coated fluorovanadium sodium phosphate composite positive electrode material, a preparation method thereof and a sodium ion battery composite positive electrode. Background The energy safety is formed as the core of the national safety system, is an important foundation for sustainable development of national economy, and is a strategy resource for driving high-quality development of economy. Development of electrochemical energy storage technology with high energy density, high power density, low cost and long cycle life is needed to build new energy systems. In a plurality of energy storage schemes, the sodium ion battery has become a global research and development hot spot by virtue of obvious resource endowment advantages (the abundance of the crust of the sodium element reaches 2.74%) and cost competitiveness (the cost of raw materials is reduced by 30% -50% compared with that of a lithium battery). The technology has a similar working principle with a lithium ion battery, and can be compatible with the existing mature production process system of the lithium ion battery, so that the technology is regarded as a strategic solution in the field of large-scale energy storage. As a core component of the sodium ion battery, the positive electrode material directly determines the energy density and the comprehensive performance of the battery. Development of positive electrode active materials with high specific capacity, excellent rate characteristics and long-cycle stability is a key technical challenge for promoting commercial application of sodium ion batteries. Among the many candidate materials, sodium vanadium fluorophosphate (Na 3V2(PO4)2F3) is recognized as one of the most promising high energy density sodium-electricity positive electrode materials due to its high working voltage plateau (-3.8V vs. Na +/Na) and considerable theoretical specific capacity (128 mAh/g). However, as a typical representation of vanadium-based polyanion compounds, sodium vanadium fluorophosphate is still limited by the bottleneck problems of low intrinsic electron conductivity (-10 -10 S/cm) and slow ion diffusion kinetics, resulting in that the actual electrochemical performance is far from theoretical expectation. CN 105655565A discloses a composite positive electrode material of sodium ion battery and its preparation method, which coats amorphous carbon layer on the outer layer of nano-scale sodium vanadium phosphate and sodium vanadium fluorophosphate to improve electron conductivity of sodium vanadium phosphate and sodium vanadium fluorophosphate, multiplying power performance and cycle performance of battery, and uses strong adhesion property of dopamine in polymerization process as carbon source to calcine and form a complete amorphous carbon coating layer to increase transmission of electrons in active substance, and then introduces polymerized conductive polymer. The method improves the rate capability and the cycle capability of the composite anode material to a certain extent. However, due to the structural limitations of amorphous carbon, there are still problems such as low specific capacity and non-ideal long cycle of the battery. In recent years, carbon coating and ion doping techniques have become a research hotspot for improving the performance of sodium vanadium fluorophosphate. However, the general operation is complicated, the cost is high, and the effect needs to be further improved, so new and improved ways are required to improve the battery performance and reduce the cost. Disclosure of Invention The invention aims to solve the technical problems and provide the co-oxidized carbon coated vanadium sodium fluorophosphate composite positive electrode material which has high discharge capacity, high power, excellent cycle stability, high conductivity and high multiplying power. The invention further aims to provide a preparation method of the co-oxidized carbon coated sodium vanadium fluorophosphate composite anode material, which is simple in raw materials, simple in process and low in cost. The invention also provides a sodium ion battery composite anode containing the co-oxidized carbon coated fluorovanadium sodium phosphate composite anode material. The preparation method of the co-oxidized carbon coated sodium vanadium fluorophosphate composite anode material comprises the following steps: And step 1, adding a carbon source into mixed acid for reaction, then adding KMnO 4 for water bath reaction, finally adding hydrogen peroxide solution for co-oxidation reaction, and washing and drying after the reaction to obtain a co-oxidized carbon source, wherein the carbon source is a mixture of a one-dimensional car