Effect of graphene optimization on Ni(OH)2/V3S4 nanocomposites for enhanced charge transport and high-performance structural supercapacitors fabricated via vacuum-assisted resin transfer molding (VARTM) using woven carbon fiber

Traditional supercapacitors often rely on bulky enclosures that increase weight and reduce space efficiency, thereby limiting their suitability for compact and lightweight energy storage systems. Structural supercapacitors, which integrate energy storage functionality into load-bearing components, represent a promising approach for next-generation automotive and aerospace technologies. This study presents the synthesis and optimization of Ni(OH) 2 /V 3 S 4 and graphene-incorporated Ni(OH) 2 /V 3 S 4 ((Gr/Ni(OH) 2 /V 3 S 4 ) nanocomposites for high-performance structural supercapacitor applications. The optimized nanocomposite, containing 3 wt% graphene (Gr 3 /Ni(OH) 2 /V 3 S 4 ), exhibited an outstanding specific capacitance of 0.13 F/cm 2 at a current density of 4.5 mA/cm 2 in a three-electrode configuration. This enhanced performance is attributed to the synergistic effects among Ni(OH) 2 , V 3 S 4 and graphene, which collectively improve electrical conductivity and increase the accessibility of electroactive sites. To evaluate its structural applicability, the Gr 3 /Ni(OH) 2 /V 3 S 4 composite was coated onto woven carbon fiber (WCF) and incorporated into a structural supercapacitor device (SSD) using vacuum-assisted resin transfer molding (VARTM). The resulting SSD delivered a specific capacitance of 2.36 F/cm 2 at 16 mA/cm 2 and maintained 72 % of its initial capacitance after 50,000 charge-discharge cycles at a high current density of 0.16 A/cm 2 . Furthermore, the device achieved a high energy density of 73.75 Wh/Kg at a power density of 1000 W/Kg, underscoring its strong potential for multifunctional energy storage. These results highlight the viability of Gr 3 /Ni(OH) 2 /V 3 S 4 -based structural supercapacitors as lightweight, high-performance energy storage solutions for advanced engineering applications. • Gr 3 /Ni(OH) 2 /V 3 S 4 nanocomposite engineered for multifunctional energy storage • Graphene content optimized to enhance conductivity and electrochemical activity • Structural device fabricated via VARTM on woven carbon fiber substrate • Achieved 2.36 F cm −2 and 73.75 Wh/kg with 72 % retention after 50,000 cycles