Hollow Nanobarrels of α-Fe2O3 on Reduced Graphene Oxide as High Performance Anode for Lithium-Ion Batteries

Alpha-phase iron oxide nanoparticles (a-NPs), a-iron oxide hollow nanobarrels (a-HNBs), and a-HNBs on reduced graphene oxide (a-HNBs/RGO) for Li-ion batteries (LIBs) were synthesized by a time-efficient microwave method to improve the low electrical conductivity of iron oxide and exploit the porous structure of RGO, which prevents the volume expansion of alpha-Fe2O3 during the insertion/ extraction. On the other hand, alpha-HNBs (similar to 200 nm in diameter, similar to 360 run in length) provide a short diffusion path for Li ions and accommodate the strain generated by the volume change. The alpha-HNBs/RGO hybrid structure was synthesized by a one-step microwave-assisted hydrothermal method to bond alpha-HNBs with RGO. The as prepared alpha-HNBs/RGO electrode exhibited a superior reversible capacity of 1279 mA h g(-1) at 0.5 C after the first cycle; such a capacity was nearly recovered after numerous cycles (2nd to 100th cycle, 95%). The long-term cyclability of alpha-HNBs/RGO shows 478 mA h g(-1) after 1000 cycles. Moreover, the alpha-HNBs/RGO electrode shows a high rate capacity of 403 mA h g(-1) even at 10 C. The alpha-HNBs/RGO exhibited a better electrochemical performance that could be attributed to the absence of nanoparticle agglomeration and RGO restacking, which provided a buffer effect against the volume expansion, promoted electrical conductivity and high structural integrity.