Gismondine Cobalt Phosphate (CoPO4) as Monovalent-ion Battery Cathode Material: A First-Principles Study
Using density functional theory calculations, we investigated the electrochemical properties of gismondine CoPO4, a polymorph from the well-studied polyanionic transition metal phosphate family, for its suitability as monovalent (Li or Na) battery cathode material. We found gismondine CoPO4 to be promising for Na-ion battery cathode. It exhibits a high cell voltage of ~4 V (vs. bulk Na) and a theoretical specific capacity of 152 mAh/g. Multiple Na-ion diffusion channels in 3D within the compound were identified with low barriers ranging from 0.13–0.28 eV, and high ionic diffusivities ranging from 10-4–10-7 cm2/s. It also has a small volume change of ~ -7% upon complete sodiation to NaCoPO4.