Thermal decomposition followed by acid etching to synthesize Fe 3 O 4 @C for lithium storage

Carbon-composited ferroferric oxide (Fe3O4@C-1) was synthesized through a thermal decomposition of the chelate (Fe)2(C4H4O6)3, which can be served as the sources for both Fe3O4 and carbon. After etching in hydrochloric acid (HCl) solution for 20 min, the pyrolytic Fe3O4@C-1 turned into Fe3O4@C-2 gaining a higher specific surface area and a better electrochemical performance. As anode materials for lithium-ion batteries, the Fe3O4@C-2 sample delivers a reversible capacity of 1047 mAh g−1 at a current density of 200 mA g−1 and remains the capacity at 837 mAh g−1 after 200 cycles, while the capacity of the Fe3O4@C-1 electrode fades to only 94 mAh g−1 after 200 cycles.