Defect Chemistry in Zn3V4(PO4)6

Abstract

Zinc-ion batteries have attracted great interest for their low cost, safety, and high energy density. Recently, Zn3V4(PO4)6 has been reported to be a promising cathode material for zinc-ion batteries. The defect chemistry, diffusion of Zn-ions, and solution of dopants are examined by advanced simulation techniques. The simulation results show that the most favorable intrinsic defect is the Zn-V anti-site. A zig-zag pattern of long-range Zn2+ diffusion is observed and the activation energy of 1.88 eV indicates that the ionic conductivity of this material is low. The most promising isovalent dopants on the Zn site are Ca2+ and Fe2+. Although the solution of Ga3+, Sc3+, In3+, Y3+, Gd3+, and La3+ on the V site is exoergic, the most promising is In3+. Different reaction routes for the formation of Zn3V4(PO4)6 are considered and the most thermodynamically favorable reaction consists of binary oxides (ZnO, V2O3, and P2O5) as reactants.