One-pot synthesis of in-situ carbon-coated Fe 3 O 4 as a long-life lithium-ion battery anode

Fe 3 O 4 has been regarded as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity, low cost, and environmental friendliness. In this work, we present a one-pot reducing-composite-hydroxide-mediated (R-CHM) method to synthesize in situ carbon-coated Fe 3 O 4 (Fe 3 O 4 @C) at 280 °C using Fe(NO 3 ) 3 · 9H 2 O and PEG800 as raw materials and NaOH/KOH as the medium. The as-prepared Fe 3 O 4 octahedron has an average size of 100 nm in diameter, covered by a carbon layer with a thickness of 3 nm, as revealed by FESEM and HRTEM images. When used as anode materials in LIBs, Fe 3 O 4 @C exhibited an outstanding rate capability (1006, 918, 825, 737, 622, 455 and 317 mAh g −1 at 0.1, 0.2, 0.5, 0.8, 1.0, 1.5 and 2.0 A g −1 ). Moreover, it presented an excellent cycling stability, with a retained capacity of 261 mAh g −1 after 800 cycles under an extremely high specific current density of 2.0 A g −1 . Such results indicate that Fe 3 O 4 @C can provide a new route into the development of long-life electrodes for future rechargeable LIBs. Importantly, the R-CHM developed in our work can be extended for the synthesis of other carbon-coated electrodes for LIBs and functional nanostructures for broader applications.