ABSTRACT
In industrial cells, the evolution of fluorine takes place on carbon anode; there fore, in this chapter we consider only this kind of material. In the overall voltage applied to the cells («* 9 V), about 3 V corresponds to the anodic overvoltage. As mentioned in Section IV.A, very low values of the charge transfer coefficient and exchange current density are obtained from Tafel plots. Significant improve ments in the fluorine production process may be obtained by a better under standing of the electrochemical mechanism. A mechanism including electron transfer by tunnel effect through a passive layer of graphite fluoride CF* is described in Section IV.A.2. The exact nature of the passive film and the kinetics of the film growth are reviewed in Sections IV.B and IV.C, and the electro chemical study of the C/CFJKF • 2HF system in Section IV.D.
