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

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.