Edge sites-driven accelerated kinetics in ultrafine Fe2O3 nanocrystals anchored graphene for enhanced alkali metal ion storage

Iron oxides have been recognized as a potential electrode material for lithium-ion and sodium-ion batteries owing to their relatively ultrahigh theoretical capacity, low-cost and earth-rich resources. Nevertheless, the rapid capacity degradation and sluggish kinetics seriously limit their practical applications. Herein, the kinetics enhanced ultrafine Fe2O3 nanocrystals (~5 nm) well anchored on graphene are prepared for high-rate lithium and sodium storage. The unique structure could provide abundant electrochemical active edge sites, short ion/electron diffusion pathways, and excellent electrical conductivity, allowing for enhanced electron/ion transport/diffusion kinetics. The fabricated Fe2O3/reduced graphene oxide nanocomposite shows impressive discharge capacity (1175 mAh g−1 at 0.2 A g−1), significant rate performance (822 mAh g−1 at 5 A g−1) and stable long-term cycle durability (993 mAh g−1 after 500 cycles at 1 A g−1) as a lithium-ion battery anode. As for sodium-ion storage, it also shows high discharge capacity of 701 mAh g−1 at 0.1 A g−1 and remarkable rate performance (253 mAh g−1 at 2 A g−1). These above intriguing electrochemical performances outperform most of the so-far recorded Fe2O3 based electrodes. Such material design strategy may pave a new way for the development of outstanding performance anode materials based on earth-rich materials for energy storage application.