Molecular Synergistic Effects Mediate Efficient Interfacial Chemistry: Enabling Dendrite-Free Zinc Anode for Aqueous Zinc-Ion Batteries.

Abstract

The primary cause of the accelerated battery failure in aqueous zinc-ion batteries (AZIBs) is the uncontrollable evolution of the zinc metal-electrolyte interface. In the present research on the development of multiadditives to ameliorate interfaces, it is challenging to elucidate the mechanisms of the various components. Additionally, the synergy among additive molecules is frequently disregarded, resulting in the combined efficacy of multiadditives that is unlikely to surpass the sum of each component. In this study, the "molecular synergistic effect" is employed, which is generated by two nonhomologous acid ester (NAE) additives in the double electrical layer microspace. Specifically, ethyl methyl carbonate (EMC) is more inclined to induce the oriented deposition of zinc metal by means of targeted adsorption with the zinc (002) crystal plane. Methyl acetate (MA) is more likely to enter the solvated shell of Zn²⁺ and will be profoundly reduced to produce SEI that is dominated by organic components under the "molecular synergistic effect" of EMC. Furthermore, MA persists in a spontaneous hydrolysis reaction, which serves to mitigate the pH increase caused by the hydrogen evolution reaction (HER) and further prevents the formation of byproducts. Consequently, the 1E1M electrolyte not only extends the cycle life of the zinc anode to 3140 cycles (1 mA h cm^-2 and 1 mA cm^-2) but also extends the life of the Zn//MnO₂ full battery, with the capacity retention rate still at 89.9% after 700 cycles.