Ultrafine Fe3O4 Quantum Dots on Hybrid Carbon Nanosheets for Long-Life, High-Rate Alkali-Metal Storage

One promising and economic step towards technological advancements in Na-ion and Li-ion batteries is to develop versatile electrode materials for alkali-metal storage. Transitional-metal oxides are appealing candidates, owing to their intrinsically low cost, high capacity, and enhanced safety. However, they generally show poor activity and a short lifespan in practical use. Herein, we report the fabrication of a versatile long-life, high-rate anode material for Li/Na storage by strongly binding ultrafine Fe3O4 quantum dots onto hybrid carbon nanosheets. Such nanocomposites are advantageous for inhibiting particle aggregation, reducing ionic diffusion pathways, and enabling fast accessibility to electrolyte ions across large electrode-electrolyte interfaces. They exhibit a long lifetime of 1000 cycles, high capacities, and exceptional high rate capabilities towards alkali-metal storage, highlighting great promise in high-energy and high-power energy applications.