Zinc dendrite suppression by a novel additive combination for rechargeable aqueous zinc batteries

Abstract

With the advantages of low cost, good safety, and easy assembly, aqueous zinc batteries (AZBs) are expected to be a promising energy storage device. However, AZBs are compromised by Zn dendrites and the hydrogen evolution reaction. Herein, we use polyethylene glycol-200 (PEG-200) and benzylidene acetone (BDA) as additives in the electrolyte of AZBs in order to inhibit Zn dendrite growth and side reactions, thus improving the cycle performance of the Zn electrode. PEG-200 can be not only used as a co-solvent for BDA but also as a surfactant to achieve a uniform interfacial electric field. As a brightening agent, BDA forms a diffusion layer on the plating substrate, which increases the electrochemical polarization and nucleation overpotential, increases the number of active nucleation sites, and finally refines the grain size of the zinc deposit. The surface of the symmetric battery electrode with electrolyte containing PEG-200 additive is smooth after cycling, and dendrite formation is successfully suppressed. The Zn–Zn symmetric cell with additive-containing electrolyte has a higher nucleation overpotential and a cyclic stability for as long as 890 h (only 48 h for the unmodified symmetric cell). This is due to the adsorption of the additive on the negative electrode, which homogenizes the deposition interface and reduces the contact of the negative electrode with water.