Electrochemical Fluorination of Graphite Anode in KF-KBF4 Molten Salt

Abstract

The electrochemical behavior of graphite anode in KF-KBF 4 molten salt at 500°C was studied by means of cyclic voltammetry, electrochemical impedance spectroscopy and chronopotentiometry techniques in this present work. The results showed that I-type "CF" compound is formed at 1.5 V vs. Pt-QRE, and II-type "CF" compound is formed at 2.1 V, while fluorine gas is formed at 4.9 V. The electrochemical reaction at 1.5 V is quasi-reversible, while the electrochemical reaction at 2.1 V is irreversible. The resistance of II-type "CF" compound is higher than I-type "CF" compound, and the value of charge transfer coefficient (β) for electrochemical formation II-type "CF" compound is calculated to be 0.26.