Titanium sub-oxide coated and modified lithium iron phosphate composite material and preparation method thereof

Abstract

The invention provides a titanium sub-oxide coated and modified lithium iron phosphate composite material and a preparation method thereof. The surface of lithium iron phosphate is coated with titanium sub-oxide, the molecular formula of the titanium sub-oxide coated and modified lithium iron phosphate composite material is LiFePO4 / Ti4O7, and the covering amount of titanium sub-oxide is 5%-10%. With the adoption of the technical scheme provided by the invention, the lithium iron phosphate material is coated with and modified by titanium sub-oxide with high conductivity, so that the high-rate charge / discharge capacity of lithium iron phosphate is obviously improved, the cycling capacity degradation of lithium iron phosphate at high current density is reduced, and the high-rate cycle performance of lithium iron phosphate is further improved; at the same time, the internal resistance of a battery is effectively reduced, the specific power of a lithium iron phosphate power battery is increased, the adaptation to the deep cycle requirement of the power battery is facilitated, the preparation process is simple and convenient, and the composite material is also suitable for large-scale industrial production.

Description

technical field [0001] The invention belongs to the technical field of lithium ion materials, and in particular relates to a titanium oxide-coated modified lithium iron phosphate composite material and a preparation method thereof. Background technique [0002] The anode material of the commercialized lithium iron battery is lithium iron phosphate, which has a theoretical capacity of up to 170mAh / g, good cycle performance and safety performance, making it the main force of power lithium-ion batteries, but because lithium iron phosphate has a low Li-ion diffusion rate (10 -14 ~10 -10 cm 2 / s) and low electronic conductivity (<10 -9 s / cm), making lithium iron phosphate unable to meet the needs of power batteries. Conventionally, carbon coating is often used to improve the conductivity of lithium iron phosphate, but the specific surface area of ​​carbon is too large, the dispersion is not good, and the corrosion resistance is poor, which leads to the attenuation of batte...

AI Technical Summary

Problems solved by technology

[0002] The anode material of the commercialized lithium iron battery is lithium iron phosphate, which has a theoretical capacity of up to 170mAh / g, good cycle performance and safety performance, making it the main force of power lithium-ion batteries, but because lithium iron phosphate has a low Li-ion diffusion rate (10 -14 ~10 -10 cm 2 / s) and low electronic conductivity (-9 s / cm), making lithium iron phosphate unable to meet the needs of power batteries

Conventionally, carbon coating is often used to improve the conductivity of lithium iron phosphate, but the specific surface area of ​​carbon is too large, the dispersion is not good, and the corrosion resistance is poor, which leads to the attenuation of battery capacity

And with the requirements of high energy density and high power density for power batteries, the conductivity, cycle capacity maintenance, high rate charge and discharge performance, and fast charge performance of lithium iron phosphate need to be further improved.