Tuning the solvation structure of zinc ions via urea enables long-cycling alkaline zinc‑manganese flow batteries

This work proposes a novel strategy utilizing urea as a bifunctional anolyte additive for zinc‑manganese (Zn[sbnd]Mn) flow batteries to regulate dead zinc formation and mitigate dendrite growth. Urea reduces the rate of zinc deposition, facilitating a uniform three-dimensional deposition and offering effective protection against alkaline corrosion of zinc via surface adsorption. The results demonstrate that incorporating 0.1 M urea into the anolyte solution of alkaline Zn[sbnd]Mn flow batteries extends the cycling time to 70 h under a current density of 60 mA cm⁻², with an average coulombic efficiency (CE) of 97.1 % and an energy efficiency (EE) of 82.6 %. The results provide a promising and valuable approach to addressing the issue of zinc dendrites while also introducing an economical, sustainable, and highly reliable electrolyte alternative for Zn[sbnd]Mn flow batteries.