Positive electrode material and preparation method and application thereof

Abstract

The invention provides a positive electrode material and a preparation method and application thereof. The chemical formula of the positive electrode material is LixMnyO2, x / y is greater than or equal to 0.9 and less than or equal to 1.6, x is greater than 0, and y is greater than 0. The preparation method comprises the following steps of (1) mixing a fused salt, a manganese salt and a first lithium salt, and carrying out primary sintering to obtain a base material, and (2) mixing the base material obtained in the step (1) with a second lithium salt, and carrying out secondary sintering to obtain the positive electrode material. In the step (2), the molar ratio of all the lithium elements to all the manganese elements is 0.9-1.6. The positive electrode material provided by the invention is free of cobalt and nickel, the cost is greatly reduced, relatively high capacity can still be maintained, and meanwhile, a molten salt heating method is adopted, so that the production efficiency is further improved on the basis of further reducing the cost.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and relates to a positive electrode material and a preparation method and application thereof. Background technique [0002] With the development of the new energy market, ternary cathode materials have aroused people's research and development boom due to their advantages such as high energy density, high cycle and high safety. In the current power market, large-scale commercialized ternary materials such as NCM523 and NCM622 can satisfy power vehicles to a certain extent. At the same time, their mileage and safety performance need to be improved, and the price of cobalt and nickel in NCM continues to rise. The cost control of the battery is restricted, and cobalt metal is expensive and easily pollutes the environment. [0003] CN107215900A discloses a method for constructing a spinel structure on the surface layer of a lithium-rich manganese-based positive electrode material, by ...

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Problems solved by technology

In the current power market, large-scale commercialized ternary materials such as NCM523 and NCM622 can satisfy power vehicles to a certain extent. At the same time, their mileage and safety performance need to be improved, and the price of cobalt and nickel in NCM continues to rise. The cost control of the battery is improved, and cobalt metal is expensive and easy to pollute the environment

[0003] CN107215900A discloses a method for constructing a spinel structure on the surface layer of a lithium-rich manganese-based positive electrode material, by adding the lithium-rich manganese-based positive electrode material into a weak acid aqueous solution to perform Li + with H + Ion exchange, and then heat-treat the ion-exchanged cathode material to transform the lithium-deficient surface structure into a spinel structure, and obtain a lithium-rich manganese-based cathode material with a spinel structure on the surface. This method is simple and low in cost, but difficult Control the number of ion exchange in each batch, the repeatability is poor

[0004] CN108615875A discloses a lithium-rich manganese-based positive electrode material and its preparation method. First, a solution containing phosphate is prepared, added to the suspension of lithium-rich manganese-based positive electrode material, and an intermediate product is obtained after reaction and drying. Lithium-rich manganese-based positive electrode materials coated with phosphate on the surface and spinel structure on the surface were obtained by calcination. The lithium-rich manganese-based positive electrode materials prepared by the method in this document have improved the first Coulombic efficiency, rate performance, cycle stability and High temperature performance, but this method needs to prepare two different solutions first, dry and sinter at high temperature, which consumes a lot of energy and makes mass production difficult

[0005] CN109585833A discloses a lithium-rich manganese-based modified material and its preparation method and positive electrode material. By preparing a gel on the surface of the lithium-rich manganese-based material, the lithium-rich manganese-based material with a spinel structure coating layer is obtained after drying and calcination. Modified materials improve the rate performance of lithium-ion batteries and reduce the voltage drop, but the gel method has high requirements for raw materials and high energy consumption, so it is rarely used in industry

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