Dilute Aqueous-Aprotic Electrolyte Towards Robust Zn-Ion Hybrid Supercapacitor with High Operation Voltage and Long Lifespan

Abstract

Highlights A novel aqueous/aprotic electrolyte with low salt concentration (i.e., 0.5 m Zn(CF3SO3)2+1 m LiTFSI) demonstrated an expanded electrochemical window, which can simultaneously stabilize Zn metal anode and increase the operation voltage of Zn-ion hybrid supercapacitors. The coordination shell of the electrolyte induced by acetonitrile and LiTFSI can not only suppress the Zn corrosion and hydrogen evolution reaction but also promote the cathodic stability and ion migration, which is depicted by the density functional theory simulations together with experimental characterizations. The Zn-ion hybrid supercapacitor based on the developed electrolyte can operate within 0–2.2 V in a wide temperature range with an ultra-long lifespan (> 120,000 cycles).

Keywords

• Zn-ion supercapacitors
• Zn metal anode
• Electrolyte engineering
• Hydrogen bonds
• Solvation structures