Carbon nanotube modified lithium-rich manganese-based positive electrode material and preparation method thereof

Abstract

The invention belongs to the field of lithium ion battery material preparation, and in particular relates to a preparation method of a carbon nanotube modified lithium-rich manganese-based positive electrode material xLi2MnO3. (1-x) LiMO2. According to the preparation method, a precursor and a carbon nanotube are modified at the same time in a pre-oxidation mode; a conductive network combination of the carbon nanotube and the positive electrode material can be formed; and the conductivity of the prepared material is improved. The preparation method comprises the steps of uniformly mixing a transition metal salt solution according to a stoichiometric ratio, dropwise adding a precipitant and a complexing agent, washing and drying to obtain a precursor, stirring, dispersing and drying the precursor and a carbon nanotube aqueous dispersion, adding into an oxidant solution for pre-oxidation, drying, mixing with a lithium source, calcining and cooling to obtain a final product. The lithium-rich manganese-based material disclosed by the invention not only has high specific capacity, but also has excellent rate capability and cycle performance. A lithium ion battery adopting the positive electrode material has huge application potential in the aspect of power batteries.

Description

technical field [0001] This patent belongs to the field of lithium ion battery material preparation, and specifically relates to a carbon nanotube modified lithium-rich manganese-based positive electrode material and a preparation method thereof. Background technique [0002] High-performance cathode materials for lithium-ion batteries are the bottleneck that restricts the development of next-generation high-energy-density lithium-ion batteries. Therefore, the development of long-cycle, high-capacity, and high-rate cathode materials for lithium-ion batteries is one of the current research hotspots. Layered lithium-rich manganese-based cathode materials have many advantages, such as high specific capacity, low cost, and environmental friendliness, but the following problems limit their practical applications: high irreversible capacity and low initial Coulombic efficiency ( <80%); poor rate performance, unable to meet the requirements of high-power charging and dischargin...

AI Technical Summary

Problems solved by technology

The third method is mainly to coat the surface with metal oxides, fast ion layers and carbon, etc., wherein coating with carbon is a method to improve the electronic conductivity of the bulk material. However, it is often relatively difficult to obtain a complete and uniform carbon coating layer. difficulty

However, carbon nanotubes are prone to agglomeration and are difficult to disperse uniformly. By increasing the strength and time of mechanical dispersion, the morphology of the positive electrode will be destroyed and the performance will be affected. Adding a chemical dispersant will introduce inactive substances into the electrode. The conductive network of carbon nanotubes formed on the surface of spherical particles can enhance the electrical conductivity between secondary particles, but it cannot improve the electrical conductivity between a large number of primary particles inside the secondary particles.

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