A dual electrolyte additive strategy for achieving stable Zn anodes for zinc-ion batteries†
Abstract
Aqueous zinc-ion batteries (AZIBs) have drawn substantial interest due to their high security, cost-effectiveness, and eco-friendly attributes. However, the prevalent challenges associated with the hydrogen evolution reaction (HER) and zinc dendrites are impeding their commercialization. Electrolyte engineering has emerged as a potent strategy for improving the stability of Zn anodes. In this study, we introduced glycine and graphene oxide (GO) into the ZnSO4 electrolyte, functioning as dual additives, to improve the performance of Zn anodes. It is found that glycine can modulate the Zn2+ solvation structure, reducing the interaction between Zn2+ and SO42−. Thus, both the HER and sulfate byproducts can be inhibited. Moreover, GO can adsorb onto the electrode, forming an rGO layer, serving both as a protective layer and a nucleation layer. More significantly, it facilitates charge transfer and promotes uniform zinc deposition, thereby enabling a homogeneous electric field distribution. Consequently, the integration of glycine and GO into the ZnSO4 electrolyte boosts the stability of Zn anodes. Zn||Zn cells can work steadily for over 700 h at 5 mA cm−2 and 1 mA h cm−2. An impressive CE of ca. 98.6% over 1300 cycles is achieved in Zn||Cu cells in the electrolyte with dual additives. Besides, Zn||VO2 full cells utilizing the electrolyte with additives also exhibit the improved cycling stability. Therefore, this study introduces a feasible approach to simultaneously mitigate the HER and Zn dendrites.