Bifunctional electrolyte additive for stable Zn anode: Reconstructing solvated structure and guiding oriented growth of Zn

Abstract

Aqueous Zn-ion batteries (AZIBs) have been considered as one of the most auspicious large-scale energy storage systems, However, the hydrogen evolution, side reaction and dendrite growth of Zn anode severely hinder its practical application and scalability. Herein, an effective and economical strategy to resolve these problems by introducing a bifunctional additive uridine into electrolyte is reported. Through theoretical calculations and experimental results, it is revealed that uridine molecules can replace some of H2O molecules in the solvated Zn2+, thus suppressing the side effects caused by H2O. In addition, it can also induce the uniform deposition of Zn on (002) plane with a close-packed morphology due to the strong absorption ability of uridine to Zn (002) plane. Benefiting from these two merits, the optimized uridine-containing electrolyte enables a highly reversible Zn plating/stripping cycling in Zn||Cu asymmetric cells for over 600 cycles with a high coulombic efficiency of 99.6% and in Zn||Zn symmetric cells for over 4500h at 1mA cm−2. As a proof-of-concept, the full cells assembled with different types of cathodes also deliver excellent cycling performance, favoring the practical application. This work has important guiding significance for improving the electrochemical performance of zinc anode.