Trace Amount of High-Concentration Electrolyte for High-Performance Aqueous Zn Metal Anodes

In recent years, the demand for energy storage equipment has been increasing, and aqueous zinc ion batteries with high safety and environmental protection have attracted widespread attention. However, their lifespan remains limited due to severe side reactions and the growth of zinc dendrites. Up to now, a lot of work has been done on electrolyte additives, but the comprehensive influence of the electrolyte concentration and volume on aqueous zinc ion batteries has received less attention. In the process of battery assembly, too much electrolyte will lead to low energy density of the whole battery, so it is necessary to explore trace electrolytes. In this study, the corrosion of the zinc anode and the growth of zinc dendrites were effectively inhibited by using 30 μL of trace high-concentration electrolyte. The results showed that the symmetric cell with 3 M ZnSO4 electrolyte exhibited a stable cycle for 3000 h at 1 mA cm–2. The activation energy of the zinc deposition process was reduced. The reversibility of zinc electroplating/stripping was improved, and the average Coulombic efficiency of Zn|3 M ZnSO4|Cu half cell was ∼99.9% after 800 cycles at 5 mA cm–2. Additionally, the specific capacity of the Zn || activated carbon capacitor was 93.2 mAh g–1 after 6000 cycles at 5 A g–1. This indicates that trace high-concentration electrolytes can effectively improve the performance of aqueous zinc ion energy storage devices. At present, the evaluation of electrochemical performance comparison of zinc metal anode is inconsistent. The investigation of trace electrolyte concentration in this study is instrumental in establishing a robust anode assessment criterion for zinc ion batteries and facilitating the rapid advancement of zinc ion battery technology.