Design of LiFePO4 and porous carbon composites with excellent High-Rate charging performance for Lithium-Ion secondary battery

Abstract

Lithium iron phosphate (LFP) is one of the promising cathode materials of lithium ion battery (LIB), but poor electrical conductivity restricts its electrochemical performance. Carbon coating can improve electrical conductivity of LFP without changing its intrinsic property. Uniform coating of carbon on LFP is significant to avoid charge congregation and unpreferable redox reactions. It is the first time to apply the commercial organic binder, Super P® (SP), as carbon source to achieve uniform coating on LFP as cathode material of LIB. The simple and economical mechanofusion method is firstly applied to coat different amounts of SP on LFP. The LIB with the cathode material of optimized SP-coated LFP shows the highest capacity of 165.6 mAh/g at 0.1C and 59.8 mAh/g at 10C, indicating its high capacity and excellent high-rate charge/discharge capability. SP is applied on other commercial LFP materials, M121 and M23, for carbon coating. Enhanced high-rate charge/discharge capabilities are also achieved for LIB with SP-coated M121 and M23 as cathode materials. This new material and technique for carbon coating is verified to be applicable on different LFP materials. This novel carbon coating method is expected to apply on other cathode materials of LIB with outstanding electrochemical performances.

Keywords: Carbon coating; High-rate; Lithium ion battery; Lithium iron phosphate; Mechanofusion; Super P®.