Facile synthesis of mesoporous MnCo2O4@MoS2 nanocomposites for asymmetric supercapacitor application with excellent prolonged cycling stability

A synergistic effect occurs in material science when a composite material's physical and chemical properties increase significantly as compared to its individual components. In the present work, MnCo2O4 (MCO) and MnCo2O4@MoS2 (MCOS) nanocomposites have been synthesized using the co-precipitation synthesis process. The main focus of the present research is to observe the impact of MoS2 on the electrochemical characteristics of the nanocomposites while keeping the MCO precursor quantity constant. The MCOS nanocomposite was synthesized with a homogeneous dispersion of 20 % MoS2 (MCOS20). It has the most significant enhancement in electrochemical properties due to its larger specific surface area (44 m2g−1) and mesoporous distribution of pore size. The MCOS20 nanocomposite as a single electrode possesses larger specific capacitances of 512 F g−1 at 0.5 A g−1 and exhibits a good rate capability. Besides that, the electrode exhibits excellent cycling stability of 91.87 % along with the coulombic efficiency of 99.57 % up to 5000 consecutive cycles, even at a high current density of 8 A g−1. An asymmetric supercapacitor (ASC) device has been fabricated with the MCOS20 nanocomposite as a cathode and commercially purchased activated carbon as an anode electrode to examine the practical utility of synthesized composite material. The device displays the highest specific energy density and power density of 36 Wh kg−1 and 19 kW kg−1, respectively. The device shows excellent stability up to 20,000 cycles at 3.5 A g−1 with a coulombic efficiency of 98.85 % and capacitance retention of 94.28 % in 6 M KOH gel electrolyte. Furthermore, the two devices illuminate red, blue, and yellow LEDs. It lights up for more than 3 min a red LED. We believe that our proposed MCOS20 nanocomposite has potential for use as electrodes in the fabrication of high-performance supercapacitor devices, owing to its simple manufacturing method and good electrochemical performance.