Method for preparing lithium iron phosphate and lithium nickel cobalt manganese oxide composite cathode material

Abstract

The invention relates to a method for preparing a lithium iron phosphate and lithium nickel cobalt manganese oxide composite cathode material. The method comprises the following steps: cathode active materials, including lithium iron phosphate and lithium nickel cobalt manganese oxide, are respectively mixed with a conductive agent to obtain a mixture, ball-milling is performed on the two mixtures, pre-coating is performed, the two pre-coated mixtures are mixed to obtain a mixture, then dry or wet ball-milling is performed, and then the mixture is dried, crushed and graded so as to obtain the surface-coated lithium iron phosphate and lithium nickel cobalt manganese oxide composite cathode material. By adopting the method provided by the invention, the cycle performance of a lithium nickel cobalt manganese oxide lithium-ion battery can be improved, the over-charging and over-discharging problem of the battery is solved, and the service life of the battery can be prolonged. The cathode material is formed by mixing lithium iron phosphate and lithium nickel cobalt manganese oxide, no new material needs to be prepared, only these two cathode materials need to be mixed evenly, and therefore no cost is increased obviously.

Description

technical field [0001] The invention relates to a method for making a lithium-ion battery composite cathode material, belonging to the technical field of chemical power sources. Background technique [0002] Lithium-ion batteries have the advantages of high working voltage, small size, light weight, no memory effect, no pollution, small self-discharge and long cycle life, and are ideal energy carriers for development in the 21st century. Lithium-ion batteries are widely used in energy storage power systems such as water conservancy, thermal power, wind power and solar power stations, uninterruptible power supplies for post and telecommunications, and power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields At the same time, lithium-ion batteries have been widely used in portable electrical appliances such as laptops, cameras, and mobile communications due to their unique performance advantages; the developed larg...

AI Technical Summary

Problems solved by technology

However, the poor electronic conductivity of lithium iron phosphate is well known, and the rechargeable voltage is relatively low. The electrochemical performance of the lithium iron phosphate lithium battery produced is poor; the shortcoming of low stacking density of lithium iron phosphate has been ignored and avoided by people. be resolved, hindering the practical application of the material

The ternary material has excellent electrochemical performance, high energy density, high voltage platform, ideal crystal structure, small self-discharge, no memory effect and other outstanding advantages; it is now widely used in lithium-ion batteries, but its high-temperature performance has defects , and the rate performance and structural stability are not as good as lithium iron phosphate. Compared with lithium iron phosphate lithium-ion batteries, the ternary material lithium-ion battery has poorer high temperature performance, cycle performance and structural stability.

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