VOPO₄·2H₂O as a new cathode material for rechargeable Ca-ion batteries

Abstract

VOPO₄·2H₂O, as a new cathode material for Ca-ion batteries, exhibits a discharge capacity of 100.6 mA h g^-1, excellent cycling stability (200 cycles) and good rate performance (42.7 mA h g^-1 at 200 mA g^-1). In situ X-ray diffraction and in situ Raman results demonstrate the calcium-ion-storage mechanism of VOPO₄·2H₂O is a single-phase reaction based on asymmetric Ca²⁺ insertion and deinsertion.