Hybrid Supercapacitors Based on Nanoporous Carbon and CoFe<sub>2</sub>O<sub>4</sub> Derived from a Bimetallic Organic Framework
Rakhee Bhosale, Sneha Bhosale, Vijay Chavan, Chitra Jambhale, Deok‐kee Kim, Sanjay S. Kolekar
Abstract
The rational design of nanomaterials derived from a metal–organic framework (MOF) has received a lot of interest due to their high potential for energy-storage and conversion applications, which are because of their high conductivity, strong redox activity, and large specific surface area. In this study, a “one-for-all” approach was used to synthesize positive and negative electrodes from a single bimetallic cobalt–iron metal–organic framework (CoFe 2 -MOF) to fabricate a hybrid supercapacitor (HSC) device. Hierarchical bimetallic CoFe 2 -MOF architectures were synthesized by a straightforward and scalable solution method. The cobalt ferrite was prepared by annealing the bimetallic CoFe 2 -MOF in air, and the nanoporous carbon (NPC) was achieved by heating the CoFe 2 -MOF in an inert atmosphere. The CoFe 2 -MOF-derived NPC exhibits a high specific capacitance of 1271 F g –1 at 2 mA cm –2 current density with an excellent cycle stability of 96.87% even after 5000 cycles due to its huge surface area of 614 m 2 g –1 and plenty of mesopores in it. The as-prepared cobalt ferrite and NPC derived from CoFe 2 -MOF were employed to construct the “all-in-one” HSC device using poly(vinyl alcohol)–potassium hydroxide as a gel–polymer electrolyte. At 1 mA cm –2 current density, the manufactured “all-in-one” HSC device shows a high specific capacitance of 112.1 F g –1, an energy density of 56.2 Wh kg –1, and a power density of 1091.5 W kg –1 . It demonstrated a high cyclic stability of 97.91% of its original capacitance over 5000 subsequent galvanostatic charge–discharge cycles with a Coulombic efficiency of 98.54%. This discovery might significantly progress research toward the creation of MOF-derived electrode materials for a bright future in energy-storage and conversion.