Effects of annealing on electrochemical performance in graphene/V2O5 supercapacitor

Multilayered graphene films uniformly coated with a thin V2O5 layer (graphene/V2O5 composite) is prepared through a combination of laser reduction and low-temperature atomic layer deposition (ALD). In order to verify the effect of the crystallinity on the electrochemical performance of the graphene/V2O5, first, we perform high-temperature annealing and then the detailed comparative study between amorphous and crystalline V2O5 coated graphene is carried out. We observe that the graphene coated with amorphous V2O5 can ensure far better performance as a supercapacitor electrode (i.e. specific capacitance, energy density, and cyclic stability) than the crystalline counterpart. Contrary to the initial intuition, the annealing is revealed to be less helpful for enhancing the overall electrochemical performance of the graphene/V2O5 composite electrode, similar to the case of the battery.