Applying Glycerol Triacetate as a Multi-Hydrogen-Bond Acceptor Co-solvent to Realize Ultra-Wide Temperature Zn Metal...

Although aqueous Zn metal batteries (ZMBs) possess high-safety and low-cost, their practical application is hindered by inferior performances at extreme temperatures (< -20°C or > 50°C). Herein, glycerol triacetate (GT) was used as a multiple hydrogen-bond acceptor (HBA) co-solvent to construct a hybrid electrolyte with limited content of GT (6 mol%) for ZMBs. Plentiful HBA sites in GT couple with hydrogen atoms of water to break hydrogen bond (HB) networks between H₂O molecules, which greatly lowers the freezing point of the hybrid electrolyte. Additionally, GT introduction reduces active H₂O amount by optimizing the solvated Zn²⁺ structure to restrain hydrogen evolution reaction (HER) and electrode-corrosion at elevated temperatures. Furthermore, GT even facilitates the entry of trifluoromethanesulfonate (OTf^-) anions into inner solvation shell of Zn²⁺, forming a robust solid electrolyte interphase (SEI) that not only enhances high-temperature stability but also improves low-temperature interfacial ion-transport of anodes. Hence, Zn//Zn symmetric cells achieve exceptional cycling stability over 3300 h at -60 °C and maintains stable operation for 560 h at 100°C. Especially, Zn//KVOH (KV₁₂O₃₀•nH₂O) full cell delivers a remarkable capacity of 398.1 mAh g^-1 at 5 A g^-1 under 100°C, with a capacity retention of 73.2% after 1000 cycles, which is among the best high-temperature performances in recent reports.