Highly crystallized perovskite-type NaFeF3 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 Fe2+/Fe3+ 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.
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