Scalable Preparation of LiFePO4/C Nanocomposites with sp2-Coordinated Carbon Coating as High-Performance Cathode Materials for Lithium-Ion Batteries

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. We hereby report carbon-coated LiFePO4 cathode materials prepared by industrial ball milling and a solid-state reaction with Li2CO3, NH4H2PO4, and FeC2O4⋅2H2O as starting materials. Soluble starch as the primary carbon source was investigated for its capability of generating a highly graphitic carbon coating, whilst sufficiently controlling the crystal growth of LiFePO4. XRD analysis, Raman spectroscopy, and electrochemical testing revealed the significant impact of the amount of starch added to the pre-sintered precursor on phase purity, carbon quality, and electrochemical performance of the final LiFePO4/C composite. The optimum soluble starch content to achieve a highly sp2-coordinated carbon coating is 10wt%, which enabled our LiFePO4/C composite to achieve competitive reversible capacities as well as improved rate performance.