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.