Electrochemical investigation on chlorine and electrolyte intercalation into graphite anodes during magnesium electrolysis process

Cyclic voltammetry (CV) was used to investigate chlorine and electrolyte intercalation into three different graphite anodes from NaCl-KCl-MgCl2 melts at 700 degrees C. The three anodes were composed of needle-coke (NC), petroleum-coke (FPC) and common petroleum-coke (CPC), respectively. Chlorine intercalation amount was characterized by the reduction current (reduction electricity quantity) on the reverse scan during the cyclic voltammograms. And the electrolyte intercalation was presented by the increase in oxidation charge between the forward scan and the reverse scan during the CV measurements. The results show that among the three graphite anodes, NC shows the lowest reduction current and nearly no increase in the charges, while about 5-10 times increase in the charge for the PFC and CPC. The above results implied that NC has a better resistance to electrolyte and chlorine intercalation, which were confirmed by the electrolysis experiments results. As a simple and useful method, CV can be used to test graphite anode corrosion resistance to electrolyte and chlorine in chloride system.