Hybrid Composite Based on Porous Cobalt‐Benzenetricarboxylic Acid Metal Organic Framework and Graphene Nanosheets as High Performance Supercapacitor Electrode

Abstract

AbstractPoor electrical conductivities, structural instabilities and long synthesis procedures, limit the application of metal organic frameworks (MOFs) in energy storage systems. In the present work, we synthesize a cobalt‐benzene tricarboxylic acid based MOF (CoBTC MOF) via two different approaches i. e. solvothermal route and mechanochemical grinding for its utility in energy storage. When characterized structurally and electrochemically, the CoBTC MOF synthesized by mechanochemical method is found to be superior because of large surface area, enhanced porosity/diffusion process through MOF and structural robustness along with less time requirement. Further, its hybrid composite with graphene nanosheets (CoBTC MOF/GNS) was prepared for its performance as a supercapacitor material. The characterization reveals the formation of sandwich structure where CoBTC MOF rods (thickness ranging from 0.5 to 2 μm) are placed in between GNS. This arrangement has resulted into high specific capacitance of 608.2 F.g−1 at current density of 0.25 A.g−1 in 1 M KOH electrolyte along with excellent capacitance retention up to 94.9% after 2000 charge/discharge cycles. Also, a symmetric supercapacitor has been assembled for practical application of CoBTC MOF/GNS which demonstrates specific capacitance of 183.2 F.g−1 with high energy density and power density of 49.8 Wh.kg−1 and 1025.8 W.kg−1 respectively, along with 92.1% retention of initial capacitance after 5000 charge‐discharge cycles.