TEGDME Electrolyte Additive for High-performance Zinc Anodes

Aqueous zinc ion batteries (AZIBs) are expected to have a wide range of applications for large-scale electrochemical energy storage systems, but their practical application is severely limited by the presence of zinc dendrites, hydrogen evolution reactions (HER), corrosion reactions, and other problems. Electrolyte optimization is considered to be one of the most effective methods for improving zinc anodes due to its simplicity, low production cost and remarkable effectiveness in suppressing zinc dendrite growth. In this paper, a tetra (ethylene glycol) dimethyl ether (TEGDME) electrolyte additive was used to improve the stability of the zinc anode by adding 0.1 g/L TEGDME to the conventional ZnSO4 electrolyte to prepare a mixed electrolyte. The effect of TEGDME on the side reactions of zinc anode was first assessed by linear sweep voltammetry (LSV) and potentiodynamic polarization. The effect of TEGDME on the structure and morphology of zinc surfaces was observed using an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). And finally, the electrochemical performance of Zn∣Zn symmetric cells, Zn∥Ti asymmetric cells and Zn-MnO2 full cells with ZnSO4 + TEGDME electrolyte was tested by cyclic voltammetry (CV) and galvanostatic cycling. The results show that the addition of TEGDME improves the surface wettability of the Zn anode and reduces the growth of dendrites through solvation structure modulation to suppress HER and zinc corrosion. Thus, TEGDME keeps the Zn anode to maintain a flat surface during charging and discharging, improving the reversibility of plating/stripping. The cycle life of the Zn∥Ti asymmetric cell was improved and the Coulombic efficiency was 100% after 100 cycles. The Zn∥Zn symmetric cells can be cycled stably for 1800 h at a current density of 1 mA/cm2 and a fixed capacity of 1 mA·h/cm2, while the capacity retention of the Zn-MnO2 full cell can be effectively improved from 51.46% to 68.29% at 100 cycles. By using TEGDME electrolyte additives, the cycle life of aqueous zinc ion batteries can be effectively improved, providing a new idea for the development of highly reversible zinc anodes.