Reconfiguring the Coordination Structure in Deep Eutectic Electrolytes for Enabling Stable Operation of Zinc-Ion Batteries

Highly stable aqueous Zn-ion batteries are of great importance for commercial applications. The challenging issues of interfacial side reactions and rampant dendrite growth cause short circuit and premature failure of aqueous Zn-ion batteries. Herein, a hydrated deep eutectic electrolyte is formulated to tackle such problems, which adopts 1,3-propanediol as a cosolvent. 1,3-Propanediol molecules can enter into the Zn²⁺ solvation structure to from a lean-water electrolyte and drastically diminish the activity of water molecules through reinforcing the hydrogen bond network. Meanwhile, PDO molecules exclude the neighboring water to modulate the electric double layer configuration, thus impeding water-mediated side reactions and inducing an inorganic-rich interphase. Consequently, this hydrated deep eutectic electrolyte ensures long-term stability of Zn-Zn, Zn-Cu, and Zn-I₂ cells. The favorable influence exerted by PDO molecules provides the guidance for constructing high-performance aqueous Zn-ion batteries.