Fe3 O4 Nanoparticles Embedded in Uniform Mesoporous Carbon Spheres for Superior High- Rate Battery Applications

Robust composite structures consisting of Fe3O4 nanoparticles (approximate to 5 nm) embedded in mesoporous carbon spheres with an average size of about 70 nm (IONP@mC) are synthesized by a facile two-step method: uniform Fe3O4 nanoparticles are first synthesized followed by a post-synthetic low-temperature hydrothermal step to encapsulate them in mesoporous carbon spheres. Instead of graphene which has been extensively reported for use in high-rate battery applications as a carbonaceous material combined with metal oxides mesoporous carbon is chosen to enhance the overall performances. The interconnecting pores facilitate the penetration of electrolyte leading to direct contact between electrochemically active Fe3O4 and lithium ion-carrying electrolyte greatly facilitating lithium ion transportation. The interconnecting carbon framework provides continuous 3D electron transportation routes. The anodes fabricated from IONP@mC are cycled under high current densities ranging from 500 to 10 000 mA g(-1). A high reversible capacity of 271 mAh g(-1) is reached at 10 000 mAh g(-1) demonstrating its superior high rate performance.