Electrochemical impedance spectroscopy study on intercalation and anomalous diffusion of AlCl_4^- ions into graphite in basic molten salt

摘要

Electrochemical impedance spectroscopy (EIS) was employed toinvestigate diffusion of AlCl_4^- ions in basic (AlCl_3-NaCl-KCl)molten salt. Nyquist plots in different DC offset potentials showedfinite and restricted aluminum ion diffusion due to insertion andblocking in the graphite electrode. The general Warburg, openWarburg, and short Warburg impedance in the complex Nyquist plot ofthis system showed the anomalous diffusion behavior of the ions in thegraphite electrode. The diffusion coefficient of the AlCl_4^- ionswas calculated from the slope of the Warburg line in a totallyblocking film in the graphite electrode and was found to be 2.8 imes10^{-10} cm^2/s.