Highly Solubilized Urea as Effective Proton Donor‐Acceptors for Durable Zinc‐Ion Storage Beyond Single‐Anion Selection Criteria

Abstract

Urea, as one of the most sustainable organic solutes, denies the high salt consumption in commercial electrolytes with its peculiar solubility in water. The bi‐mixture of urea‐H2O shows the eutectic feature for increased attention in aqueous Zn‐ion electrochemical energy storage (AZEES) technologies. While the state‐of‐the‐art aqueous electrolyte recipes are still pursuing the high‐concentrated salt dosage with limited urea adoption and single‐anion selection category. Here, a dual‐anion urea‐based (DAU) electrolyte composed of dual‐Zn salts and urea‐H2O‐induced solutions is reported, contributing to a stable electric double‐layer construction and in situ organic/inorganic SEI formation. The optimized ZT2S0.5‐20U electrolytes show a high initial Coulombic efficiency of 93.2% and durable Zn‐ion storage ≈4000 h regarding Zn//Cu and Zn//Zn stripping/plating procedures. The assembled Zn//activated carbon full cells maintain ≈100% capacitance over 50 000 cycles at 4 A g–1 in coin cell and ≈98% capacitance over 20 000 cycles at 1 A g–1 in pouch cell setups. A 12 × 12 cm2 pouch cell assembly illustrates the practicality of AZEES devices by designing the cheap, antifreezing, and nonflammable DAU electrolyte system coupling proton donor‐acceptor molecule and multi‐anion selection criteria, exterminating the critical technical barriers in commercialization.