Iron-assisted carbon coating strategy for improved electrochemical LiMn0.8Fe0.2PO4 cathodes

An iron-assisted carbon coating strategy is developed to guide the formation of uniform and highly graphitized carbon layers on surfaces of the LiMn0.8Fe0.2PO4 (LMFP) to yield cathode materials with improved electrochemical performance. A small amount of iron oxalate is added as a catalyst precursor, which decomposes into ferrous oxide (FeO) at high temperature. During the calcination process, FeO is reduced to iron (Fe) that helps to transform amorphous carbon into graphitized carbon which is deposited uniformly and tightly on surfaces of LMFP materials. The impact of Fe atoms on the formation of highly graphitized carbon layers as well as the electrochemical performances of the resulting LMFP/Fe/Carbon (LMFP/Fe/C), is evaluated. Compared to LMFP/C without iron oxalate, LMFP/Fe/C exhibited substantial discharge capacity and better rate and cycling performances. Discharge capacities of 152.3, 141.9, 132.1, 105.6 and 76.0 mAh g−1 are recorded at 0.2, 0.5, 1, 5 and 10 C, respectively. The retention capacity remained 78.6% at 10 C after 60 cycles. Furthermore, the conductivity and the lithium ion diffusion processes of LMFP/Fe/C are improved.