Synthesis by Electrolysis of Iron-Based Fluoride as Cathode Materials for Lithium ion Batteries

다국어 초록 (Multilingual Abstract)

The hydrated iron fl uoride (Fe 3 F 8 ·2H 2 O) with mixed valence cations is successfully synthesized through a rapid electrolyticsynthesis route for the fi rst time using low-concentration HF solution as fl uorine source and cheap carbon steel as iron source.
By controlling the value of current density, submicron structured hydrated iron fl uoride with diff erent grain sizes is obtained.
The thermal behavior of Fe 3 F 8 ·2H 2 O under air atmosphere is studied. The product cooling to room temperature after heattreatment is FeF 2.2 (OH) 0.8 ·0.33H 2 O, which is determined by X-ray diff raction (XRD), X-ray photoelectron spectra (XPS),Fourier transform infrared spectrometer (FT-IR), and thermogravimetry/diff erential scanning calorimetry (TG/DSC). Theevaluation of the electrochemical performance of FeF 2.2 (OH) 0.8 ·0.33H 2 O as a cathode for lithium batteries shows that it hasan initial discharge capacity as high as 580 mAh g −1 in a wide voltage range of 1.0–4.5 V at a current density of 20 mA g −1 ,but the cycle performance is not very satisfactory, only 170 mAh g −1 after 50 cycles.