A kind of lithium cobalt phosphate cathode material and preparation method for lithium ion battery

Abstract

The invention relates to the technical field of lithium ion batteries, and provides a lithium cobalt phosphate positive electrode material for a lithium ion battery and a preparation method thereof. According to the invention, doping is performed on the lithium cobalt phosphate by Fe3+; modified multi-walled carbon nanotubes are added during the preparation of precursor particles so that the carbon nanotubes partially coat the surfaces of the particles, and are partially embedded in the particles; then sintering is performed to obtain composite particles where the carbon nanometers are interpenetrated with the Fe3+ doped lithium cobalt phosphate; then polypyrrole is synthesized in situ on the surfaces of the composite particles; high temperature treatment is further performed to convert the polypyrrole into a nitrogen-doped carbon layer; and the carbon nanotubes on the surfaces of the lithium cobalt phosphate particles are connected together to form a dense conductive network, therebyobtaining a lithium cobalt phosphate positive electrode material. Compared with the conventional method, by use of the preparation method of the invention, the electronic conductivity and ionic conductivity of the lithium cobalt phosphate positive electrode material can be significantly improved; the decomposition of the electrolyte is inhibited; the specific capacity is increased; and the cycle performance is improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and provides a lithium cobalt phosphate cathode material for lithium ion batteries and a preparation method thereof. Background technique [0002] Lithium-ion battery is a new generation of green high-energy battery with excellent performance. It has the following characteristics: high voltage, high capacity, low consumption, no memory effect, no pollution, small size, small internal resistance, less self-discharge, and more cycles. Because of the above-mentioned characteristics, lithium-ion batteries have been applied to many civilian and military fields such as mobile phones, notebook computers, video cameras, and digital cameras. [0003] The main constituent materials of lithium-ion batteries include electrolyte, separator materials, positive and negative electrode materials, etc. Cathode materials account for a relatively large proportion. Cathode materials have always been th...

AI Technical Summary

Problems solved by technology

For example, the conductivity is poor due to the wide band gap, and, at a higher operating voltage (not lower than 5V), the electrolyte decomposes at the electrode / electrolyte interface, resulting in unstable cycle performance, which will cause phosphoric acid The rapid attenuation of specific capacity and the decrease of electrochemical activity of cobalt-lithium materials affect the performance and service life of positive electrode materials

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