Highly porous ZIF-67/KLAC composite for enhanced supercapacitor performance with redox additive electrolyte

Abstract

To enhance the efficiency of supercapacitors, the selection of appropriate electrode materials as well as electrolytes is essential. Highly porous materials have gained attention as electrode material while Redox Additive Electrolytes (RAE) have gained popularity as effective alternatives to traditional aqueous electrolytes. The present study discusses the fabrication of a highly porous Co-MOF (ZIF-67) grown on Keekar leaves-derived activated carbon (KLAC) to develop a suitable composite using a simple and inexpensive approach. The grown ZIF-67 material shows a polyhedron kind of morphology over the surface of KLAC with an overall surface area of 1012 m2/g. The synthesized material was evaluated for a three-electrode configuration in a 1 M Na2SO4 aqueous electrolyte and 0.2 M K3[Fe(CN)6] in 1 M Na2SO4 (RAE). The ZIF-67/KLAC composite exhibits a high capacitance of 2880 F/g when electrochemically tested within RAE, at a specific current of 5 A/g as compared to 33.11 F/g when tested in 1 M Na2SO4 aqueous electrolyte, over a potential range of −0.1–0.5 V. Also, the cyclic stability in RAE is found to be superior (∼100 %) as compared to 1 M Na2SO4 (∼95.30 %) after continuous 5000 charge-discharge cycles. The lower resistance in RAE allows for faster ionic and electronic transmission, resulting in superior cyclic stability. Due to the excellent electrochemical outcomes, the suggested synergic of ZIF-67/KLAC/RAE may work as a highly effective supercapacitor assembly in the future.