Synergistic Effect of NiCo(OH)2 in Electrospun Polyacrylonitrile Nanofibers for Enhanced All Solid State Supercapacitor Performance

Supercapacitors (SCs) are essential components in next-generation energy storage systems due to their excellent power density and fast charge-discharge capability. However, their limited energy density continues to impede broader adoption. This study explores the electrochemical properties of electrospun polyacrylonitrile (PAN) nanofiber composites doped with nickel and cobalt hydroxide (NiCo(OH) 2 ) nanoparticles to address this challenge. The fabrication process involves electrospinning PAN solutions with NiCo(OH) 2 precursors, followed by heat treatment to enhance the structural and electrochemical properties. The crystallographic structure and morphology of the composite fibers were examined using standard characterization techniques. XPS analysis confirmed the presence of Ni 2+ , Ni 3+ , Co 2+ , and Co 3+ states, while BET analysis revealed a high surface area of 99 m 2 g -1 and mesoporous structure; TEM images confirmed uniform nanofiber morphology with embedded nanoparticles. Electrochemical testing showed that the synergistic effect of NiCo 2 O 4 /PAN carbon nanofibers improved specific capacitance, rate performance, and cycling stability, signifying progress toward advanced SCs. The highest specific capacitance achieved was 440 F g -1 at a current density of 1 A g -1 . A supercapacitor device, composed of NiCo 2 O 4 /PAN-carbon NFs//AC electrodes and a PVA/KOH gel electrolyte, demonstrated an energy density of 6 Wh kg -1 at a power density of 2000 Wk g -1 . Furthermore, it exhibited exceptional cycling stability, retaining 98% of its capacitance after 5000 cycles, highlighting its solid electrochemical reversibility, which is crucial for practical SC applications.