Preparation of carbon-coated MnFe2O4 nanospheres as high-performance anode materials for lithium-ion batteries

Carbon-coated MnFe2O4 (MnFe2O4@C) nanospheres were successfully synthesized by a facile two-step method involving the preparation of MnFe2O4 nanospheres and subsequent pyrolysis treatment. The structure and morphology of the composite were characterized by XRD, SEM, TEM, and HRTEM. The MnFe2O4 nanospheres with a diameter of 300–400 nm are composed of many nanocrystals (10–15 nm). The surfaces of MnFe2O4 nanospheres were coated uniformly with thin carbon shells with a thickness of 3–5 nm. The MnFe2O4@C composites, as anode material for Li-ion battery, showed greatly enhanced electrochemical performance with high lithium storage capacity, satisfactory cyclic durability, and rate capacity compared with the pristine MnFe2O4. The reversible capacity of the MnFe2O4@C composites was retained at 646 mAh g−1 after 50 cycles at 100 mA g−1. Even when cycled at various rates for 50 cycles, the capacity could recover to 626 mAh g−1 at the current of 100 mA g−1. The MnFe2O4@C nanospheres exhibit excellent electrochemical performance as a potential candidate for anode material in high-energy lithium-ion battery.