Defect induced improved capacitive performance of MnS incorporated MoO3 nanocomposite for supercapacitor electrodes in aqueous electrolytes.

Electrode materials play a crucial role in improving supercapacitor performance. In this work, MnS nanoparticles were incorporated into MoO3 to form a MoO3/MnS nanocomposite via hydrothermal synthesis, and the capacitive performance of the resulting supercapacitor electrodes was evaluated. Their electrochemical performances were studied in conjunction with KCl and Na2SO4 electrolytes. The generation of MoO3/MnS nanocomposite was confirmed by XRD analysis and HR-TEM imaging. It is found that the MnS nanoparticles altered the morphology of MoO3 from nanobelts to nanofibers and produced a defective, rough surface. The defective surface expanded the interlayer distance from 0.396 nm to 0.421 nm. In both ionic electrolytes, the MoO3/MnS composite demonstrated higher capacitive performance than the pristine MoO3. At 0.3 A g-1 current density, the estimated specific capacitance of MoO3/MnS was 387 F g-1 and 335 F g-1 in KCl and Na2SO4 electrolytes, respectively. In the symmetric two-electrode system, the MoO3/MnS shows a specific capacitance of 297 F g-1 at 1 A g-1, with an energy density of 33.37 Wh kg-1 and a power density of 450 W kg-1. The MoO3/MnS nanocomposite provides excellent 90% retention after 1000 continuous charging-discharging cyclic. The enhancement of electrochemical performance is attributed to the large surface area, defective morphology, and broader interlayer distance. This system bridges the gap between traditional batteries and capacitors, offering a unique approach to producing supercapacitor electrodes.