Inclusion of Carbon Dots in the Electrolyte for Augmenting Reversible Cycles of the Zinc Anode in Zinc-Ion Batteries.

This study investigates the use of trace nitrogen-doped carbon dots (N-CDs) that are synthesized by low-cost natural molecules of citric acid and β-alanine as an additive in the ZnSO electrolyte for augmenting the zinc anode in aqueous zinc-ion batteries. A variety of experimental results demonstrate that an inclusion of N-CDs could facilitate the desolvation of zinc ions through coordination interactions, thereby regulating zinc-ion nucleation, improving uniform deposition of zinc ions, and inhibiting hydrogen precipitation on the zinc electrode surface. Various in situ and ex situ measurements of interfacial and surface engineering suggest that the N-CDs additive in the electrolyte could show intense affinity with zinc ions and form a self-assembled adsorption film on the zinc electrode film, thus inhibiting zinc anode corrosion and effectively suppressing side reactions. It is shown that zinc dendrite growth during the zinc-ion plating/stripping process during cycling of zinc-ion batteries could be prevented by the added N-CDs, thereby boosting the long reversible stability of the zinc anode. Hence, the notable improvement of the cycling performance of zinc-ion batteries could be achieved by an introduction of N-CDs in the electrolyte. This study provides deep insights into the use of low-cost and eco-friendly N-doped carbon quantum dots in aqueous zinc metal batteries, displaying great promise for practical applications.