Mesoporous VO2(B) nanorods deposited onto graphene architectures for enhanced rate capability and cycle life of Li ion battery cathodes

Abstract

Monoclinic vanadium dioxide (VO2(B)) is considered as a promising cathode material for lithium ion batteries (LIBs) owing to its high capacity, short ion diffusion channel, and multiple oxidation states. However, VO2(B) is technically limited due to its low electronic conductivity and large volume expansion. In order to resolve these drawbacks, we develop a mesoporous composite of reduced graphene oxide (rGO) and VO2(B) for enhanced rate capability and cycle life of LIB cathode. The uniform deposition of VO2(B) nanorods onto the mesoporous surface of the rGO architecture provides a facile access of Li ions to the storage site, large accessible area, short diffusion pathway, and chemical and mechanical stabilities. The VO2(B)/rGO composite electrode achieves a high capacity of 226 mA h g−1 at current density of 50 mA g−1 and superior capacity retention of 67.5% even at 40 times increase in current density up to 2000 mA g−1. In addition, this composite electrode demonstrates long cyclic stability of 88.5% after 500 cycles at 1000 mA g−1. In situ synchronous X-ray absorption spectroscopic data confirms a reversible change of the local structure and valence state evolution during a charging and discharging process.