Enhancing the ultra-high rate capability of manganese-based olivine cathode by in situ catalytic growth of graphene carbon layer

Manganese-based olivine is a high energy and low-cost cathode material for lithium-ion batteries. However, its low electronic and ionic conductivity limits its further application. Herein the graphene-modified LiMn0.8Fe0.2PO4 (LMFP/C-Fe) composites are prepared by in-situ pyrolysis and catalytic graphitization through trace ferrocene as catalyst precursor. The average thickness of graphene carbon layer grown in situ is about 2–3 nm, which forms a dense and uniform carbon layer along the face of LMFP granules. It has been found that this unique structure can make a significant improvement to the electrical conductivity of LMFP. The as-prepared LMFP/C-Fe composite has a high discharge capacity of 155.9 mAh/g at 0.5C, and the capacity retention is 93.8 % after 300 charge-discharge cycles. In addition, the material can still provide reversible capacity of 94.4 mAh/g even at an ultra-high current rate of 30C. Therefore, this work offers new tactics for layout and preparation of long-life, low cost and high-energy density lithium-ion batteries, which will present a promising application in electric automobile and other applications.