High-Performance Supercapacitor Devised Using Nickel Cobalt Sulfide-Terephthalic Acid Composite

This study presents a high-performance nickel–cobalt sulfide–terephthalic acid (NCS–BDC) composite electrode synthesized via a simple solvothermal route for advanced supercapacitor applications. The integration of the BDC organic linker promotes a highly mesoporous architecture and creates abundant active sites, compensating for the material’s moderate surface area. The resulting NCS–BDC electrode exhibits exceptional electrochemical properties, delivering a high specific capacitance of 1698.87 F g–1 at 0.5 A g–1 in a 2 M KOH electrolyte. When configured into an asymmetric supercapacitor (ASC) using activated carbon, the device achieves a maximum energy density of 52.29 Wh kg–1 and demonstrates outstanding stability, retaining 92% of its initial capacitance after 5000 cycles. Ex-situ XRD confirms that the intrinsic structural integrity of the cubic spinel phase is perfectly preserved postcycling. These findings establish NCS–BDC as a robust and promising electrode material for next-generation energy storage.