Erythritol-strengthen electrolytes effectively improve the electrochemical stability window of aqueous symmetric supercapacitor

Due to the advantages of high safety, high conductivity and low cost, the supercapacitor with aqueous elec-trolytes exhibits the great prospects in the future energy storage market. However, the narrow electrochemical stability window (ESW) of electric double-layer supercapacitor leads to its low energy density, which seriously limits its application. Herein, we demonstrate erythritol (Et) additive could efficaciously decrease the water molecules in the solvation sheath and break the hydrogen bond network of aqueous electrolytes, which resulting in expanded ESW. Especially, symmetric supercapacitor based on 37.9% Et additive to 1 M LiTFSI electrolyte expands ESW from 1.8 to 2.1 V, and the energy density increased to 13.3 Wh kg(-1) with high specific capacitance of 86.6F g(-1) and the capacitance retention rate of 73.8% after 10,000 cycles. Therefore, this study affords an efficient strategy to achieve high energy density aqueous supercapacitor.