Cobalt-doped pyrochlore-structured iron fluoride as a highly stable cathode material for lithium-ion batteries

Abstract

In the search of high-performance cathodes for next-generation Li-ion batteries (LIBs), iron fluorides are among the most promising materials because of their extremely high theoretical capacity. This study reports on the synthesis, structural and electrochemical characterizations of cobalt doped iron fluoride hydrate as a high-performance cathode material for LIBs. A simple non-aqueous precipitation method is used to synthesize cobalt doped iron fluoride (Fe0.9Co0.1F3·0.5H2O) while its structural and electrochemical properties are also evaluated. The thermogravimetric analysis reveals that the structure of the as-prepared material remains stable up to 243°C. The structure was then found to collapse beyond this temperature due to the removal of water contents from the crystal structure. The material delivers a high discharge capacity of 227mAhg−1 at 0.1C in the potential range of 1.8-4.5V versus Li/Li+. The electrode retains a high reversible capacity of 150mAhg−1 at a rate of 0.1C after 200 cycles, indicating high reversibility and stability of the material. The electrode also shows a superior rate capability of up to 10C, showing its potential use as a cathode material for LIBs.