Ultrahigh energy density with superior cyclic stability of calcined ZIF-8 based asymmetric supercapacitor device in redox additive electrolyte

In the current work, an attempt has been made to solvothermally synthesize calcined zeolitic imidazolate framework-8 (ZIF-8) electrode to investigate the electrochemical performance in redox-additive (6 M NaOH + 0.35 M [K4(Fe(CN)6)].3H2O) electrolyte (RAE) in three- (3E) and two- (2E: asymmetric supercapacitor (ASSC) device) electrode systems. Further, the structural and morphological characterizations reveal the formation of cubic phase, hexagonal morphology, and narrow mesoporous with a large specific surface area (S BET = 1089 m2/ g). The fabricated electrode in the 3E setup divulges an outstanding specific capacity, cyclic stability, and coulombic efficiency of 637.5 & 687.5C/g (10 A/g & 1 mV/s), 324.6 %, and 94.4 %, respectively after 5000 cycles. Furthermore, the ASSC device was constructed utilizing activated carbon (AC) as a negative electrode and calcined ZIF-8 as a positive electrode. At 32 A/g, the device offers a significant specific capacitance of 290.4 F/g, minimal charge-transfer resistance (Rct) of 0.54 Omega, energy density (Ed) of 161.33 Wh/kg, and power density (Pd) of 22,338.00 W/kg with ultrahigh cyclic stability (150 %) and coulombic efficiency (120 %) after 8500 cycles. Moreover, at 110 A/g, an ASSC shows a good cyclic stability and coulombic efficiency of 70 % and 100 % from 8500 to 13,500 cycles, respectively. The three ASSC devices lighten the distinct colour light-emitting diodes, underscoring their electrochemical stability and durability.