Electrowetting of Molten Carbonate Electrolytes

Abstract

AbstractThe wetting characteristics of various molten carbonate electrolytes were experimentally measured and the dependence of the contact angle on polarisation was thoroughly examined for various temperatures and gas atmospheres. At open circuit under an atmosphere of CO2 and/or oxidant gases, addition of alkaline earth carbonates decreases the wettability of the electrolyte. Addition of alkaline earth carbonates also tends to decrease the temperature dependence of the contact angle. Upon polarisation, the contact angle shows a complex behaviour. In an oxidising atmosphere its dependence on potential is roughly symmetric (like an electrocapillary curve) but in a reducing atmosphere this is not the case. Generally, the contact angle increases upon cathodic polarisation but decreases in the anodic direction. These changes in contact angle are interpreted in terms of interfacial tensions. The complex dependence of contact angle on polarisation can be interpreted in terms of a superimposed electrocapillary and transport effects. As such, it may be affected by specifically adsorbed species at the electrode surface (especially complex oxides), by the basicity (oxide ion activity) of the melt, and by the potential‐induced segregation of the cationic species in the carbonate melt.