No abstract

Secondary Zn–based batteries are a valid alternative to Li for stationary storage, but commercial devices are not yet available, chiefly owing to anode shape‐change and passivation issues. Mildly acidic aqueous solutions are actively studied, since they seem to limit unstable growth of Zn, with respect to the alkaline ones, customary for primary batteries. Additives can further improve the performance of mildly acidic electrolytes. In this work we focus on the impact of a series of quaternary ammonium salts (TBAB, CTAB, DMDTDAB, BDMPAC, BPPEI, PDADMAC), selected to represent a comprehensive range of molecular functionalities. Electrochemical measurements (cyclic voltammetry, chronopotentiometry and galvanostatic‐cycling in split‐cells), combined with 2D and 3D imaging techniques (SEM, stereomicroscopy and in situ tomography) were adopted for the assessment Zn behaviour. This multi‐technique approach pinpointed TBAB as the single most effective additive for low‐current density operation, while at high current densities the additive‐free electrolyte allows better cycling performance, coherently with similar results for alkaline electrolytes.

The Cover Feature shows a schematic representation of Zn plating from an aqueous electrolyte in the presence of Quaternary Ammonium Salts (QASs) (upper part) and in an additive‐free solution (bottom element). The study provides insight into the cycling behavior of zinc anodes in battery context, using QASs as additives in mildly acidic aqueous electrolytes. The cover was designed by one of the paper authors: Elisa Emanuele. More information can be found in the Research Article by B. Bozzini et al.