Exploring MOF-199 composites as redox-active materials for hybrid battery-supercapacitor devices

Metal-organic frameworks (MOFs) have emerged as intriguing porous materials with diverse potential applications. Herein, we synthesized a copper-based MOF (MOF-199) and investigated its use in energy storage applications. Methods were adapted to intensify the electrochemical characteristics of MOF-199 by preparing composites with graphene and polyaniline (PANI). The specific capacity of the synthesized MOF in a three-electrode assembly was significantly enhanced from 88 C g^-1 to 475 C g^-1 and 766 C g^-1 with the addition of graphene and polyaniline (PANI), respectively. Due to the superior performance of (MOF-199)/PANI, a hybrid supercapacitor was fabricated with the structure of (MOF-199)/PANI//activated carbon, which displayed an excellent maximum energy and power density of 64 W h kg^-1 and 7200 W kg^-1, respectively. The hybrid device exhibited an appreciable capacity retention of 92% after 1000 charge-discharge cycles. Moreover, using Dunn's model, the capacitive and diffusive contributions as well as the k ₁ and k ₂ currents of the fabricated device were calculated, validating the hybrid nature of the supercapattery device. The current studies showed that MOF-199 exhibits promising electrochemical features and can be considered as potential electrode material for hybrid energy storage devices.