Enhanced cycle stability of iron(II, III) oxide nanoparticles encapsulated with nitrogen-doped carbon and graphene frameworks for lithium battery anodes

Nitrogen-doped carbon-coated and graphene oxide-wrapped Fe₃O₄ nanoparticles were prepared using the electrostatic force between polyethyleneimine-functionalized Fe₃O₄ nanoparticles and graphene oxide layers, followed by annealing in an N₂ atmosphere (Fe₃O₄@NCG). The electrochemical performance of Fe₃O₄@NCG was superior to that of graphene oxide- or reduced graphene oxide-wrapped Fe₃O₄ nanoparticles and carbon-coated Fe₃O₄ nanoparticles. Fe₃O₄@NCG exhibited stable specific capacity of ∼895 mAh g⁻¹ after 350 cycles over the voltage range 0.001–3.0 V vs. Li/Li⁺. The superior performance of Fe₃O₄@NCG was attributed to the presence of a nitrogen-doped carbon layer and networks of reduced graphene oxide. The chemical route-derived Fe₃O₄@NCG may be a promising anode material for high-performance lithium-ion batteries.