Defective Metal–Organic Framework-808@Polyaniline Composite Materials for High Capacitance Retention Supercapacitor Electrodes

Among their potential applications, metal–organic frameworks (MOFs) emerge as promising alternative electrode materials to overcome the disadvantages of low energy density supercapacitors. Although the potential of MOFs lies in their adjustable pore structure and high surface areas, they possess poor conductivity. In this context, composites with conductive matrices, including organic conductive polymers, have proved to enhance the electrochemical properties of MOFs and their structural stability in the long-term cycling process compared to the pristine MOF. In this study, we have chosen defective zirconium MOF-808 (d-MOF-808) as a porous material because of its resistance to strong acidic media in a postsynthetic modification process. As a conductive agent, polyaniline (PANI) was selected due to its high stability and facile synthesis. The obtained composites of d-MOF-808@PANI at d-MOF/PANI ratios of 15:1, 30:1, and 60:1 increase the charge transport properties compared to the pristine d-MOF-808 and PANI. Electrochemical evaluation of the new hybrid electrode materials was made to demonstrate the capacitance retention. Among the series of materials prepared, the 60:1 composite shows the highest capacitance (188 F/g at 30 mV s–1) in 1 M KOH and a notable capacitance retention of 99.8% for up to 10,000 cycles with 99.7% coulombic efficiency.