Factors Affecting the Performance of Oxygen-Evolving Ni–Fe–Cu Anodes in Low-Temperature Molten Fluoride Electrolyte for Aluminium Electrowinning

There is a strong push towards developing an alternative low-carbon process for the primary production of aluminiumAluminium. ElectrolysisElectrolysis with inert, oxygen-evolving anodesAnode is an attractive alternative, and alloysAlloys of Ni–Fe–Cu are promising. This paper describes results from electrochemical studies to examine the performance of such anodesAnode for different sodium–potassium cryolite electrolyte compositions from CR = (NaF + KF)/AlF3 = 1.3 to 1.4, and KR = KF/(KF + NaF) = 0.3–0.4. VoltammetryVoltammetry curves reveal how surfaceSurface treatment in the form of anodeAnode pre-oxidation reduces passivation current and improves anodeAnode stability. Also, the effect of the polarization history of the anodeAnode on the voltammetryVoltammetry characteristics and the overall long-term stability of the anodeAnode is addressed, but leaving the anodesAnode unpolarized in the electrolyte damages the dense, protective oxide layer on the anodeAnode surfaceSurface, although pre-oxidation offersOxygen-evolving electrodes some protection.