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.