MODIFICATION OF CARBON ELECTRODES BY A NITRATE-BASED TREATMENT

The modification of raw carbon electrodes by a nitrate-based treatment improves the fluorine evolution process on carbon anodes. In the case of Al(NO3)3-impregnated electrodes, these improvements are attributed to the formation, at the electrode/KF-2HF interface, of a ternary con ducting compound C(x)(AlF3)yF, i.e. a GIC, instead of insulating graph ite fluorides, CF(x). In addition, the effect of the NO3- anions of th e impregnation solution is demonstrated by impedance spectroscopy, sca nning electron microscopy and mercury porosimetry. Impregnation of cru de carbon electrodes by nitrate salts, followed by heat treatment, ind uces smoothing of the electrode surfaces and an increase in the diamet er of the pores. This treatment also improves the electronic transfer at the interface and enhances the wettability of the electrode by the melt.