Insight into organic electrolytes for rechargeable Zn-air battery

Abstract

In rechargeable zinc-air batteries (RZABs) use of aqueous electrolytes is prevalent, but this approach introduces several challenges, such as hydrogen evolution, lower electrochemical stability window, corrosion and passivation of the Zn electrodes. In this regard, the suitability of zinc organic electrolytes is explored to resolve the technical challenges associated with the aqueous electrolytes. In order to address the current challenges and research gaps, suitability of the addressed zinc organic electrolytes was investigated through analyzing their – physicochemical properties and mass transport; compositional analyses (decomposition screening), formed discharge product and reversibility during redox kinetics; corrosion and passivation phenomena of zinc metal as well as the cathodic oxygen reduction reaction (ORR) performance. Notably, this study is the first to investigate the passivation and corrosion phenomena of Zn metal anodes in organic electrolytes, establishing the correlation between cathodic ORR activity and electrolyte medium, and the decomposition process of organic electrolytes in air environment through saturating the electrolyte medium with dissolved oxygen. The study revealed that zinc triflate/DMF (Dimethylformamide) organic electrolyte has excellent reversibility, charge and mass transport, ORR activity, and minimum passivation than the zinc nitrate/DMF and zinc nitrate/DMSO (Dimethylsufoxide) organic electrolytes.