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

Abstract

ABSTRACT 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 H 2 O molecules, which greatly lowers the freezing point of the hybrid electrolyte. Additionally, GT introduction reduces active H 2 O amount by optimizing the solvated Zn 2+ 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 Zn 2+ , 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 (KV 12 O 30 •nH 2 O) 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.