A precursor with iron-rich surface and manganese-rich core and method for preparing carbon-coated lithium manganese iron phosphate material using the precursor as raw material

Abstract

The invention discloses a precursor rich in iron on the surface and rich in manganese on the core and a method for preparing a carbon-coated manganese-iron-lithium phosphate material by taking the precursor as a raw material. The primary particle size of the precursor is 15-500 nanometers; the specific surface area is 5-100 m<2> / g; iron elements are enriched 0-5 nanometers away from particle surfaces; the content of manganese within a depth range is less than 0.01 wt%; and manganese elements are intensively distributed on the cores of material particles. The method for preparing the carbon-coated manganese-iron-lithium phosphate material based on the precursor comprises the following steps: synthesizing the precursor according to the chemical formula of manganese-iron-lithium phosphate, putting the precursor, a Li-containing compound, a P-containing compound, a metal M-containing compound and a carbon source organic matter raw material into a dispersion medium, and mixing the materials to obtain a slurry; and drying and calcining the slurry to obtain the carbon-coated manganese-iron-lithium phosphate material. The precursor which is rich in iron on the surface is taken as the raw material for synthesizing the manganese-iron-lithium phosphate material, and the carbon deposition state on the surfaces of electrode material particles in a calcining process is improved, so that the electrical conductivity and electrochemical performance are improved.

Description

technical field [0001] The invention relates to a precursor with iron-rich surface and manganese-rich core and a method for preparing a carbon-coated lithium manganese iron phosphate material by using the precursor as a raw material, belonging to the technical field of chemical batteries. Background technique [0002] With the continuous development of human society, the energy consumption in daily life and industrial production continues to increase. In recent years, the portability and wirelessization of 3C electronic products, various electric tools and other power appliances have developed rapidly. The advancement of these technologies has also brought about higher consumption of energy storage and secondary batteries that can be repeatedly charged and discharged. and performance requirements. In addition, in order to protect the earth's environment and ensure energy security, in recent years, the industry of hybrid electric vehicles and pure electric vehicles using sec...

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Problems solved by technology

The main problems of this method are: 1) Repeated powder cleaning and drying treatment must be carried out after each step of synthesis, and the process is cumbersome; Very high, and it is difficult to control the reaction conditions and the purity of the resulting product in large-scale production

However, they also adopted the process route of first synthesizing the core material and then coating the shell material, which requires multi-step synthesis and heat treatment processes, which is more complicated and time-consuming

[0008] It can be seen that the methods introduced in the previous work on the preparation of surface-coated lithium iron phosphate cathode materials are very cumbersome and difficult to control, and do not make full use of different types of precursor raw materials to simplify the preparation process

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