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 Li2CO3-Na2CO3-K2CO3 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 CaCO3 can effectively protect nickel anode from Cl– induced corrosion by increasing the electrolyte basicity. [Display omitted] •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.•CaCO3 was an effectively additive to prevent the corrosion nickel anode from Cl–.