Liquid-phase synthesis of highly dispersed NaFeF3 particles and their electrochemical properties for sodium-ion batteries

Highly dispersed NaFeF3 particles were prepared at 280 degrees C by liquid-phase synthesis using high-boiling-point organic solution, and their electrochemical properties were studied by charge and discharge measurements. TEM observation clarified that the resultant NaFeF3 particles had uniform particle sizes of ca. 10-20, 100-200, and 500-600 nm, which could be controlled by the composition of the synthetic solution. The discharge capacities were higher for NaFeF3 that had smaller particle sizes, particularly at a rate of 0.1 C or higher, while the discharge capacities obtained at a rate of 0.01 C between 1.5 and 4.5 V were almost the same in the range 170-181 mAh g(-1) regardless of the particle size of NaFeF3. These results clearly indicate that the use of well-dispersed nano-sized NaFeF3 particles should effectively improve the rate performance of NaFeF3. (C) 2011 Elsevier B.V. All rights reserved.