Unveiling the supercapacitive potential of MWCNT/Zn0.76Co0.24S/Co4S3 microcauliflowers as an advanced electrode material for sustainable energy storage applications

Abstract

The fabrication of complex metal sulfide nanostructures to achieve high electrochemical performance, electrical conductivity and preserve structural integrity is an extensive research interest in the energy storage field. Therefore, in the present investigation, Zn0.76Co0.24S/Co4S3 microcauliflowers are synthesized using hydrothermal method. The prepared material is characterized by various specific techniques and further investigated as a potential electrode for supercapacitor. The specific capacitance of 1607 F g- 1 is obtained at 1 A g- 1 which is attributed to the unique microcauliflowers morphology, high surface area, connectivity of microcauliflowers and rich redox activity of Zn0.76Co0.24S/Co4S3. The capacitance of Zn0.76Co0.24S/Co4S3 microcauliflowers is found to be higher from Zn0.76Co0.24S (630 F g- 1) and Co4S3 (996 F g- 1). Further, to improve the electrochemical performance of Zn0.76Co0.24S/Co4S3, the small quantity of multi-walled carbon nanotubes (MWCNTs) is mixed with Zn0.76Co0.24S/Co4S3 microcauliflowers and improved capacitance of 2220 F g- 1 is received from MWCNT/ Zn0.76Co0.24S/Co4S3 at 1 A g- 1. Moreover, an aqueous hybrid supercapacitor device is designed by MWCNT/ Zn0.76Co0.24S/Co4S3 (positive electrode) and activated carbon (negative electrode). MWCNT/Zn0.76Co0.24S/ Co4S3//AC delivers the maximum energy density of 60.09 W h kg- 1 with power density of 800 W kg- 1. Moreover, four green color LEDs, a small motor fan and kitchen timer are also powered separately by two MWCNT/Zn0.76Co0.24S/Co4S3//AC devices connected in series.