Corrosion Investigations of Materials in Antimony–Tin and Antimony–Bismuth Alloys for Liquid Metal Batteries

Liquid metal batteries are discussed as stationary electrical energy storage for renewable energies, in order to compensate their fluctuating supply of energy. A liquid metal battery consists of three different liquids, which stay segregated due to density differences and mutual immiscibility. The negative electrode is the low-density liquid metal, and in our case sodium, a medium density molten salt, is the electrolyte and positive electrode is a high-density liquid metal. For the latter, Sb–Sn and Sb–Bi alloys are selected. However, one issue is the compatibility of structural materials with the used liquids. In a first step, the behavior of potential structural materials in Sb3Sn7 and SbBi9 at the temperature of 450 °C up to 750 h was tested. The results showed that the corrosion in SbBi9 was significantly less than in Sb3Sn7 and the most promising materials were molybdenum meta and Max-phase coatings.