Published online by Cambridge University Press: 28 May 2018
We investigate the insertion energetics of Ca at low concentrations in four promising vanadium oxide phases (α and δ vanadium pentoxide (V2O5) polymorphs as well as rutile- (R) and bronze-type (B) vanadium dioxide (VO2)) using density functional theory (DFT). We find α-V2O5 to be the most suitable material for an application as cathode, driven by a stable coordinative environment, while VO2(R) does not exhibit a stable low-concentration CaxVO2 phase due to severe distortions of the host lattice due to the large calcium ion. The results provide insight into the possibility of employing these phases as active cathode materials of Ca-ion batteries.