Long-Life and Highly Utilized Zinc Anode for Aqueous Batteries Enabled by Electrolyte Additives with Synergistic Effects

After decades of development, zinc-based batteries with the advantages of high energy density, low cost, and environmental benignity have been considered as a promising battery system in the application of energy storage. However, the poor cycle performance of zinc anode strongly restricts the cycle life of zinc-based batteries and thus limits its large-scale application. Electrolyte additives have been proven to be one of the most straightforward strategies in improving the stability of zinc anode during cycles, while the options of additives are still limited. This work is based on the in-depth investigation of the electrochemical behavior of both the organic additives and the zinc species in the electrolyte. The modification effects of poly(vinyl alcohol) (PVA) and vanillin as two typical additives from the electroplating industry in both the zinc plating and zinc anode are systematically studied. It is revealed that PVA could increase the utilization and rate performance of the anode, while greatly promoting the corrosion and shape change of the zinc anode. On the contrary, the existence of vanillin could maintain the structure of the anode during cycles, while the rate performance of the battery is hindered. With the coaddition of the PVA and vanillin, the zinc anode shows superior performance in cycle life, rate performance, active material utilization, and discharge energy retention. These findings provide insight for the enrichment of electrolyte additives in zinc-based batteries.