First principle evaluations on perovskite-type sodium trifluorides, NaMF3 (M= V, Mn, Fe, Co, Ni, and Cu), as electrode materials for Na-ion batteries

This ab initio study investigates the structural, Na diffusion channels, electrochemical, and electrical properties of NaMF3 (M= V, Mn, Fe, Co, Ni, and Cu) for as novel electrode materials for Na-ion batteries, using density functional theory (DFT) calculations. The stability and structural changes are evaluated during (de)sodiation. Considering electrochemical potential of the materials by Fermi and internal energy approaches, NaNiF3 and NaVF3 have the highest and lowest voltages, respectively. The electrical properties of the materials are examined in terms of intrinsic- and extrinsic-like band gaps. For comprehensiveness, the electrical rate-capability is estimated using two different approaches, i.e. Delta and CCTB. Consequently, utilizing various DFT approaches and evaluating properties, each considered material has its own advantages and drawbacks to be used as Na-ion electrode. Using a general perspective, this paper ranks the materials as NaCuF3, NaCoF3, NaVF3, NaMnF3, NaFeF3, and NaNiF3, respectively. This study opens a new landscape for future investigations about these promising intercalation electrode materials and also the other analogous systems.