Unlocking the Effect of Chain Length and Terminal Group on Ethylene Glycol Ether Family Toward Advanced Aqueous Electrolytes.

Abstract

Constructing high-performance hybrid electrolyte is important to advanced aqueous electrochemical energy storage devices. However, due to the lack of in-depth understanding of how the molecule structures of cosolvent additives influence the properties of electrolytes significantly impeded the development of hybrid electrolytes. Herein, a series of hybrid electrolytes are prepared by using ethylene glycol ether with different chain lengths and terminal groups as additives. The optimized 2m LiTFSI-90%DDm hybrid electrolyte prepared from diethylene glycol dimethyl ether (DDm) molecule showcases excellent comprehensive performance and significantly enhances the operating voltage of supercapacitors (SCs) to 2.5V by suppressing the activity of water. Moreover, the SC with 2m LiTFSI-90%DDm hybrid electrolyte supplies a long-term cycling life of 50000 cycles at 1Ag-1 with 92.3% capacitance retention as well as excellent low temperature (-40ºC) cycling performance (10000 times at 0.2Ag-1). Universally, Zn//polyaniline full cell with 2m Zn(OTf)2-90%DDm electrolyte manifests outstanding cycling performance in terms of 77.9% capacity retention after 2,000 cycles and a dendrite-free Zn anode. This work inspires new thinking of developing advanced hybrid electrolytes by cosolvent molecule design toward high-performance energy storage devices.