Bioderived Glycerol Carbonate Cosolvent Reconstructs Solvation Shell, Tethers Anions to the Anode, and Enables Durable Aqueous Zinc-Ion Batteries

Abstract Conventional carbonate cosolvents in aqueous Zn-ion batteries (AZIBs) suffer from flammability, toxicity, poor solubility, sluggish Zn2+ transport, and unstable solid-electrolyte interphases (SEIs), curtailing their practical viability. Here, we introduce glycerol carbonate (GC), a nonflammable, eco-friendly, inexpensive, and nontoxic cosolvent as a multifunctional alternative that revolutionizes electrolyte design. GC’s dual hydroxyl–carbonyl functionalities enable it to replace water molecules in the primary Zn2+ solvation shell and significantly reduce free water content to almost 56%. More importantly, GC strongly adsorbs on the Zn anode surface, and the hydroxyl group of GC binds the triflate anion through a distinctive “tethering effect”, producing a highly stable ZnF2-rich inorganic SEI. These promote textured (002) Zn deposition, suppress corrosion, and enable highly reversible plating/stripping for ∼1600 h. The versatility of GC is further demonstrated by mixing it with other poorly performing additives, which enhances cycle life by 2–3 times. The practical applicability of the electrolyte is demonstrated by assembling a Zn|V2O5 multilayer pouch cell that delivers a stable capacity of ∼100 mAh for ∼800 cycles. This work establishes GC as a blueprint for multifunctional cosolvents, boosting solvation modulation, ion transport, and SEI robustness, paving the way toward safe, scalable AZIBs for grid-scale energy storage.