Large-scale fabrication of graphene-wrapped FeF₃ nanocrystals as cathode materials for lithium ion batteries

Graphene-wrapped FeF₃ nanocrystals (FeF₃/G) have been successfully fabricated for the first time by a vapour-solid method, which can be generalized to synthesize other metal fluorides. The as-synthesized FeF ₃/G delivers a charge capacity of 155, 113, and 73 mA h g ^-1 at 104, 502, and 1040 mA g^-1 in turn, displaying superior rate capability to bare FeF₃. Moreover, it exhibits stable cyclability over 100 cycles with a charge capacity of 185.6 and 119.8 mA h g^-1 at 20.8 and 208 mA g^-1, respectively, which could be ascribed to the buffering effect and lowered resistance from the graphene. This versatile vapour-solid method and the improved cyclability provide a promising avenue for the application of metal fluorides as cathode materials. © 2013 The Royal Society of Chemistry.