Candidate materials for the sulfur electrode current collector—II. Aluminum and its alloys

In the continuing search for materials for the positive current collector/container of the high-temperature sodium-sulfur cell, the electrochemical behavior of aluminum alloys in polysulfide/sulfur melts has been examined. Electrochemical evidence coupled with SEM surface examination and chemical analysis of the melt have shown that aluminum materials studied remain passive within the 1.25–4.5 V potential range (Na/Na+ reference). The existence of the transpassive region currently reported in the literature has not been confirmed. Interpretation of the nature of the observed residual currents is suggested. The alloys studied can be used as self-healing substrates of conductive coatings or as matrices of composite materials in contact with the polysulfide/sulfur melts.