Comprehensive Experimental Insights into Ultra-Long Cycle Life of Zinc-Ion Batteries Inspired by Super Low Concentrations of a Derivative of Urea in the Zinc Sulfate Electrolyte

In this study, a low-cost and friendly compound diazolidinylurea carrying a number of heteroatoms and inter/intra hydrogen bonding, a derivative of urea (DU), efficiently strengthened aqueous zinc ions batteries (AZIBs) in ZnSO₄ electrolyte. The influence of DU on the zinc anode in the 2 M ZnSO₄ electrolyte was fully studied by various surface chemistry and electrochemistry means. It is demonstrated that the super low concentration of DU (2 mM, 0.00556 wt %) could inhibit the formation of zinc dendrites, zinc corrosion, and the hydrogen evolution reaction during the constant current cycling of water system ZIBs, which thus enabled symmetric zinc-zinc batteries to reach a cycle life of 7336 h (nearly 306 days) under 1 mA·cm^-2, 1 mA h·cm^-2 at 25 °C and 426 h (nearly 18 days) at 55 °C, and inspired zinc-manganese full battery to maintain a capacity retention rate of more than 52% after cycling for 1000 cycles under a current of 2 A·g^-1. These results are much superior over zinc ion cells based on the blank ZnSO₄ batteries. Even if the Zn-Cu half cells including the DU/2 M ZnSO₄ electrolyte were also more pronounced than those with the bare ZnSO₄ electrolyte. The maximum corrosion inhibition efficiency of the DU for the zinc electrode in ZnSO₄ solution exceeded 82%. Hence, the suppression of zinc corrosion and parasitic side reactions, as well as the formation and growth of zinc dendritic crystals by the addition of DU in zinc sulfate electrolyte, played a central role in intensifying aqueous zinc ion batteries.