Effect of Solid Solution Precursors on the Preparation of Limn0.7fe0.3po4/C Cathode Materials for High Performance Lithium Ion Batteries

Abstract

In this work, by using a very cheap precursor of Mn0.7Fe0.3CO3 that is synthesized through co-precipitation, a high performance LiMn0.7Fe0.3PO4/C (LMFP) is reported. This method not only makes the distribution of Fe and Mn more uniform and prevents the possibility of generating LiFePO4 and LiMnPO4 mixed phases, but also controls the size and microstructure of primary and secondary particles. LMFP-2 synthesized by this method presents the best electrochemical performance, delivering high capacity of 164.9 mAh g-1 and high capacity retention of 96% after 100 cycles at 0.1 C rate. LMFP-2 delivers 138.5 mAh g-1, and the capacity retention rate still reaches to 79.42% after 500 cycles at 5 C rate, moreover, it delivers 111.4 mAh g-1 at 20 C rate. LMFP-2 presents much better battery power than the sample LMFP-3 synthesized based on the raw materials of Fe2O3 and Mn2O3. The synthesis of Fe and Mn solid solutions by co-precipitation method can perfectly solve the difficulties in the synthesis process of high Mn materials, so as to obtain a more stable LMFP material with uniform distribution of Fe and Mn.

Keywords: LiMn0.7Fe0.3PO4, Mn0.7Fe0.3CO3, solid-solution precursor, cathode materials, Lithium-ion batteries