Novel synthesis and electrochemical properties of perovskite-type NaFeF3 for a sodium-ion battery

► Perovskite-type NaFeF 3 could be synthesized through the roll-quench method. ► The obtained NaFeF 3 achieved 100% charge/discharge efficiency with an initial capacity of 197 mAh g −1 . Highly crystallized perovskite-type NaFeF 3 has been investigated as the cathode for sodium-ion batteries through the roll-quench method. In the charge–discharge measurement, the first discharge capacity was 197 mAh g −1 at a rate of 0.076 mA cm −2 between 1.5 V and 4.5 V. Reversible Fe 2+ /Fe 3+ redox reaction on cycle was confirmed by XPS. The ex situ XRD measurements for charged or discharged NaFeF 3 pellets revealed the reversible vibration on cycle, due to the structure strength and flexibility of the corner-sharing matrix. The peak intensities of (1 1 2) and (0 0 4) were changed with accompanying insertion/extraction of sodium, suggesting the extracted sodium has returned to the original 4c site on discharge.