Citric Acid Enable Morphological Optimization of Ni 3 (PO 4 ) 2 Next Generation High Performance Hybrid Supercapacitors

Abstract

Nickel phosphate (Ni 3 (PO 4 ) 2 ) exhibiting a cabbage-like hierarchical architecture was effectively synthesized by a hydrothermal process that was carefully treated with citric acid as a surface-regulation agent. The unblemished Nickel phosphate (NP) electrode demonstrated a specific capacitance of 1090.10 F/g in a three-electrode setup. Citric acid processing resulted in a significant improvement in electrochemical efficiency, yielding specific capacitances of approximately 791.40 and 2034 F/g for NP treated with 3 mg (NPCA0.3) and 5 mg (NPCA0.5), accordingly. The notable enhancement is ascribed to citric acid-induced surface modification, augmented the electronic mobility, improved the electrolyte accessibility, and rise in electrochemically active sites. Compared to prepared samples, NPCA0.5 exhibited exceptional charge storage capabilities and was hence chosen for device manufacture. The constructed asymmetric supercapacitor device demonstrated a remarkable specific capacitance of around 228.10 F/g, a substantial energy density of 81.10 Wh/kg at a power density of 1146.10 W/kg, 2 and exceptional cycling stability with 92.3% capacitance retention after 6K cycles. The results underscore citric acid surface modification as an effective and scalable approach to markedly improve the electrochemical performances of phosphate-based electrode materials for highefficiency advanced energy storage applications.