Electrostatic Self-Assembly of Fe₃O₄ Nanoparticles on Graphene Oxides for High Capacity Lithium-Ion Battery Anodes

Abstract: Magnetite, Fe₃O_4, is a promising anode material for lithium ion batteries due to its high theoretical capacity (924 mA h g⁻¹), high density, low cost and low toxicity. However, its application as high capacity anodes is still hampered by poor cycling performance. To stabilize the cycling performance of Fe₃O₄ nanoparticles, composites comprising Fe₃O₄ nanoparticles and graphene sheets (GS) were fabricated. The Fe₃O₄/GS composite disks of mm dimensions were prepared by electrostatic self-assembly between negatively charged graphene oxide (GO) sheets and positively charged Fe₃O₄-APTMS [Fe₃O₄ grafted with (3-aminopropyl)trimethoxysilane (APTMS)] in an acidic solution (pH = 2) followed by in situ chemical reduction. Thus prepared Fe₃O₄/GS composite showed an excellent rate capability as well as much enhanced cycling stability compared with Fe₃O₄ electrode. The superior electrochemical responses of Fe₃O₄/GS composite disks assure the advantages of: (1) electrostatic self-assembly between high storage-capacity materials with GO; and (2) incorporation of GS in the Fe₃O₄/GS composite for high capacity lithium-ion battery application.