Electrochemical Characteristics of Nano-sized A 2 MnPO 4 F (A = Li, Na) as Cathode Materials for Lithium ion Batteries

Abstract

Fluorophosphate, Na 2 MnPO 4 F as new cathode material was synthesized by carbothermal treatment method. Prepared Na 2 MnPO 4 F has particle size under 100 nm and residual carbon exists in surface of Na 2 MnPO 4 F. Additional carbon coating was performed in order to increase the electrochemical properties. Even capacity and overpotential were improved by carbon coating using mechanical ball milling, the reduced crystallinity limited the drastic improvement of the electrochemical properties. To solve this problem, reheat treatment was involved to recover crystallinity and then notable improvement of electrochemical properties was obtained. Specific amount of Li + that participates in electrochemical Li + insertion / extraction reaction, was x = 1 in Li x Na 2−x MnPO 4 F within the voltage range of 2.0 to 4.8 V. The doubled capacity by 2 electron reaction can be obtained when NMPF is charged to higher voltage over 4.8 V.