A cathode material for lithium-ion batteries based on graphitized carbon-wrapped FeF3 nanoparticles prepared by facile polymerization

Abstract

Graphitized carbon-coated FeF₃ nanoparticles were synthesized by facile polymerization using FeCl₃ as an iron precursor, citric acid (C₆H₈O₇) as a carbon source and chelating agent, and ethylene glycol (EG) as a cross-linker. During the synthesis, Fe(0) was formed in situ to catalyze the formation of graphitic carbon and was subsequently transformed into FeF₃. The prepared FeF₃/graphitic carbon composite (FC853) exhibited an initial discharge capacity of about 188 mA h g⁻¹, with an excellent capacity fading rate of 0.24% per cycle for 50 cycles at 0.1C in the voltage range of 2.0–4.5 V, which is superior to the corresponding parameters of bare FeF₃. This composite also exhibited an increased discharge capacity of about 374 mA h g⁻¹ in the 1^st cycle, reaching 421 mA h g⁻¹ after slow activation processes in a wide voltage range of 1.5–4.5 V. In addition, the rate performance of FC853 was significantly improved compared to that of bare FeF₃. The enhanced electrochemical Li ion storage properties of this FeF₃ composite were mainly attributed to the controlled FeF₃ nanoparticle size and the conductive graphitic carbon layers wrapping FeF₃ surfaces during prolonged cycles.