LAUSR

Abstract Aqueous electrolytes are promising for high performance electrochemical supercapacitors. However, their present narrow electrochemical window, high-cost or toxicity , set limits for wide application. Here, we demonstrate the viability of employing the PEO-strengthened 3 m LiTFSI aqueous electrolytes, which are high-conductive and eco-friendly, for high voltage supercapacitors application. Furthermore, symmetric supercapacitor with 3 m LiTFSI/30 g L−1 PEO is assembled. High operating-voltage of 2.4 V with excellent performance (125 F g−1 at 0.5 A g−1, and 67.3% capacitance retention of 50Ag-1/1 Ag-1) and longevity (>10,000 cycles) are achieved. Therefore, this work provides an effective and promising way to prepare green and high potential window electrolyte for high-voltage operating energy storage devices.