Non-Aqueous Zn-Ion Hybrid Supercapacitors: Acetonitrile vs Propylene Carbonate Based Electrolyte

Abstract

The development of high efficiency energy storage systems is increasingly important as these systems enable utilize energy from renewable sources and reduce greenhouse gas evolution caused by fuel combustion technologies at the same time. Electrochemical characteristics of Zn-ion hybrid supercapacitor (ZIHS) cells based on 1 M acetonitrile and propylene carbonate electrolytes in zinc tetrafluoroborate (Zn(BF4)2), zinc di[bis(trifluoromethylsulfonyl)imide] (Zn(TFSI)2) and zinc trifluoromethanesulfonate (Zn(OTf)2) have been studied using cyclic voltammetry, constant current charge/discharge and electrochemical impedance methods. The Ragone plots have been calculated from constant power measurement data. Very high energy and power densities (80 Wh kg−1 and 21.2 kW kg−1) have been calculated for 1 M Zn(BF4)2/AN based Zn-ion hybrid supercapacitor. Some assembled ZIHSs had shown excellent cycling and energy stability over 20000 cycles.