Zinc Anodes Modified by One‐Molecular‐Thick Self‐Assembled Monolayers for Simultaneous Suppression of Side‐Reactions and Dendrite‐Formation in Aqueous Zinc‐Ion Batteries
Manasi Mwemezi, S. J. Richard Prabakar, Su Cheol Han, Woon Bae Park, Jung Yong Seo, Kee‐Sun Sohn, Myoungho Pyo
Abstract
Abstract Repeated charge/discharge in aqueous zinc‐ion batteries (ZIBs) commonly results in surface corrosion/passivation and dendrite formation on zinc anodes, which is a major challenge for the commercialization of zinc‐based batteries. In this work, metallic Zn modified by self‐assembled monolayers is described as a viable anode for ZIBs. ω‐mercaptoundecanoic acid that is spontaneously adsorbed on Zn (MUDA/Zn) contributes to the simultaneous suppression of side reactions and dendrite formation in ZIBs. Though one‐molecular‐thick, densely packed alkyl chains prohibit H 2 O and H + from making direct contact with the underlying Zn, and surface carboxylate moieties (–COO ‐ ) effectively repel anionic species (OH ‐ ) in a solution, which renders a Zn anode inert against zincate formation within a wide range of pH. In contrast, the electrostatic attraction between surface‐carboxylates and cations increases the concentration of Zn 2+ on the surface of MUDA/Zn to facilitate Zn plating/stripping with less overpotentials. The high concentration of Zn 2+ also results in an increased number of nucleation sites, which enhances the lateral growth of Zn with no formation of dendrites. As a result, MUDA/Zn shows excellent stability during prolonged Zn plating/stripping within a wide range of pH. The advantageous properties of MUDA/Zn are also retained in full‐cells coupled with δ‐MnO 2 cathodes.