Electrochemical Behavior of Graphite in KF–AlF[sub 3]-Based Melt with Low Cryolite Ratio

The electrochemical behavior of graphite in -based melt with a cryolite ratio (molar ratio of KF to ) of 1.3 as well as a low oxygen content at was investigated by cyclic voltammetry, potentiostatic electrolysis, sampled-current voltammetry, and chronopotentiometry. Aluminum deposited on graphite at a potential of ca. 0.25 V (vs Al) and the electrochemical intercalation of potassium into graphite occurred at ca. −0.1 V (vs Al). The intercalation of potassium into graphite enhanced the formation of . The deposition of aluminum on graphite was a linear diffusion-controlled process, while its reverse reaction involved kinetic limitations. Sampled-current voltammetry results indicated that the aluminum deposition on graphite was depressed in the potential region extending from about 0.1 to 0.03 V (vs Al). Chronopotentiometry results revealed that the critical cathodic current density for potassium intercalation was about .