Chloride impurity induced corrosion of nickel anode and its protection in molten Li2CO3-Na2CO3-K2CO3

It is well-known that Cl – can cause localized corrosion of metal in aqueous solutions, but its effect on material corrosion under anodic polarization in molten salts is less known. Herein, the effect of Cl – on the stability of nickel anode in molten Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 was investigated. There existed a critical corrosion concentration of Cl – (0.2 mol% at 650 °C), above which serious corrosion of nickel anode took place. Cl – reduced the compactness and adherence of oxide scales. It was found that the addition of CaCO 3 can effectively protect nickel anode from Cl – induced corrosion by increasing the electrolyte basicity. • The critical Cl – concentration to pitting corrosion of nickel anodes was identified as 0.2 mol% at 650 °C. • Cl – induced corrosion mechanism of nickel anodes was revealed. • Potential-basicity diagram of nickel in molten carbonate was constructed. • CaCO 3 was an effectively additive to prevent the corrosion nickel anode from Cl – .