Fabrication of MnCo2O4@PANI nanocomposites as electrode material for high-energy density asymmetric supercapacitor

In this work, the co-precipitation method has been utilized to synthesize MnCo2O4 (MCO) and MnCo2O4@Po- lyaniline (PMCO) nanocomposites. The wt% of polyaniline (PANI) has been varied from 0 to 30 %, keeping the MnCo2O4 precursor quantity constant. The nanocomposite with 20 wt% PANI (P20MCO) exhibits better electrochemical properties compared to other synthesized nanocomposite samples. The P20MCO nanocomposite exhibits specific capacitances of 765 F g- 1 at 0.5 A g- 1 and 88.13 % capacitance retention over 10,000 consecutive cycles. An asymmetric supercapacitor (ASC) has been constructed using P20MCO as cathode and commercially activated carbon as anode. The fabricated ASC device exhibits outstanding cycling stability with 91.48 % capacitance retention for 45,000 cycles at 12 A g- 1 . The ASC has the highest power density of 14.3 kW kg- 1 and specific energy density of 58 Wh kg- 1 . Moreover, a red LED is illuminated by a single device and putting two devices in series light the blue, green, and white LEDs. These ASCs glow a red LED for more than 13 min. Our results suggest that the P20MCO nanocomposite-based supercapacitor devices will be promising for energy storage applications because of their easy production approach and good electrochemical performance.