Nanoarchitectonics for ultrahigh capacitance with superior energy and power density of sustainable zeolitic imidazolate framework-67 in redox additive electrolyte

The present work reported a sustainable zeolitic imidazolate framework-67 in redox additive electrolyte with ultrahigh capacitance and superior energy & power density as potential electrode materials for energy storage applications. The interest stems from its unique combination of desirable characteristics and reveals novel high-performance supercapacitors (SCs). The work employs redox additive electrolyte (RAE), specifically 0.08 M [K₃(Fe(CN)₆)] in 6 M KOH. When synthesized dodecahedral structured material was tested in a 3-electrode (3E) setup, it presented an ultrahigh specific capacitance (C_S) of 8307.38 Fg^-1 at a current density of 2 Ag^-1 and a worthy cycling performance with 88.25% initial capacitance retention after 10,000 cycles. The asymmetric supercapacitor device (ASSC) fabricated shows impressive energy density (E), reaching 49.80 Whkg^-1 at a current density of 4 Ag^-1 with an exceptional C_S of 917.83 Fg^-1. Remarkably, it also delivers a high power density (P) of 1361.38 Wkg^-1 at the same current density. The ASSC devices showed outstanding stability that stays almost 90% of the initial capacitance even after 10,000 charge-discharge cycles at an ultrahigh current density of 80 Ag^-1 along with good columbic efficiency. The wide potential window, ranging from 0.0 to 1.6 V, further increases their potential applications. In essence, this work paves the way for a new generation of supercapacitors by combining electrodes with a tailored electrolyte, achieving exceptional E and P alongside remarkable stability.