Silica and nitrogen-doped carbon co-coated lithium manganese iron phosphate microspheres as cathode materials for lithium batteries

Abstract

Lithium manganese iron phosphate (LiMn1-xFexPO4, LMFP) combines the advantages of LiFePO4 and LiMnPO4. However, low electronic conductivity and sluggish lithium ion diffusion of the LMFP cathode limits its commercial application. In this work, the LMFP microspheres were co-coated by silica and N-doped carbon for the improvement of electronic and ionic conductivity of LMFP. The hydrolysis of tetraethyl orthosilicate and the polymerization of dopamine can be mutually promoted in one reaction system to realize the simultaneous precipitation of Si and C species on the LMFP surfaces without the addition of acid–base catalysts or buffering agents. After high-temperature treatment in argon, the silica and N-doped carbon co-coated LMFP microspheres were obtained with improved cycling stability (84.4% of capacity retention for 300 cycles at 1 C) and enhanced rate performance (80.0 mAh g−1 at 5 C). Therefore, this work shows a facile and common method for the composite coating of cathode materials.