Tungsten Carbide Nano Sponge: A Dual-Application Material for Lithium-Ion Batteries and Supercapacitors

Tungsten carbide (WC) has emerged as a promising material for advanced lithium-ion batteries (LIBs) and supercapacitor technologies owing to its remarkable intrinsic properties. This study reports the synthesis of porous tungsten carbide (WC) via a simple and efficient solid-state route to obtain a phase-pure WC nanosponge (WC-NS) with a unique nanostructured morphology that enhances electrochemical performance, making it a promising electrode material for LIBs and supercapacitors. The WC-NS was characterized using X-ray diffraction, high-resolution scanning electron microscopy (HRSEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) to elucidate its structural and compositional attributes. As an LIB anode, it delivered an initial specific capacity of 454 mA h/g at 1000 mA/g, retaining 244 mA h/g after 200 cycles with 99.9% Coulombic efficiency. In supercapacitor applications, WC-NS demonstrated outstanding electrochemical performance, achieving 334 F/g at 1 A/g and 102 F/g at 8 A/g, while maintaining 98% retention over 5000 cycles with 100% Coulombic efficiency. A symmetric WC-NS supercapacitor exhibited a capacitance of 300 F/g at 0.8 A/g, 98% retention over 20,000 cycles, a maximum power density of 3600 W/kg, and an energy density of 30 Wh/kg. The comprehensive post-mortem analyses of WC confirm its stable nanoporous structure without any noticeable degradation even after prolonged cycling in both LIBs and supercapacitor. These results demonstrate the exceptional versatility and promise of WC as a next-generation multifunctional material for cutting-edge energy storage applications.