Carbon-Coated Fe–Mn–O Composites as Promising Anode Materials for Lithium-Ion Batteries

Abstract

Fe–Mn–O composite oxides with various Fe/Mn molar ratios were prepared by a simple coprecipitation method followed by calcining at 600 °C, and carbon-coated oxides were obtained by pyrolyzing pyrrole at 550 °C. The cycling and rate performance of the oxides as anode materials are greatly associated with the Fe/Mn molar ratio. The carbon-coated oxides with a molar ratio of 2:1 exhibit a stable reversible capacity of 651.8 mA h g^–1 at a current density of 100 mA g^–1 after 90 cycles, and the capacities of 567.7, 501.3, 390.7, and 203.8 mA h g^–1 at varied densities of 200, 400, 800, and 1600 mA g^–1, respectively. The electrochemical performance is superior to that of single Fe₃O₄ or MnO prepared under the same conditions. The enhanced performance could be ascribed to the smaller particle size of Fe–Mn–O than the individuals, the mutual segregation of heterogeneous oxides of Fe₃O₄ and MnO during delithiation, and heterogeneous elements of Fe and Mn during lithiation