Synthesis of worm-like binary metallic active material by electroless deposition approach for high-performance supercapacitor

Abstract

Finding a convenient low-cost method to prepare a promising charge storage material for high-performance supercapacitors remains always a critical challenge. Herein, the facilely eco-friendly electroless electrolytic (EE) technique was employed to deposit a worm-like Ni-Co-P nanofilm directly on nickel foam (NF) substrate. Gross morphology and microstructure of the as-prepared active material were confirmed by SEM, EDS and XRD techniques. The supercapacitive properties of Ni-Co-P/NF electrode was studied in 6.0 M KOH solution by cyclic voltammetry (CV), galvanostatic charging/discharging (GCD) and electrochemical impedance spectroscopy (EIS). CV curves displayed a pair of two broad current peaks (Ip) associated with the reversible redox reactions within the fabricated Ni-Co-P. The high slope value of the linear relationship Ip vs. υ1/2 reveals readily accessible diffuse pathways due to a porous texture of Ni-Co-P active material. Its specific capacitance increased with the decrease in the scan speed achieving 222.16 F/g at a 1.0 mV/s. The observed definite plateaus in the charging/ discharging profile confirms the battery-like behavior of Ni-Co-P prepared material. Its pseudocapacitive charge storage mechanism was analyzed based on the power law (I(v) = a υb). Ni-Co-P showed an excellent rate performance, where its coulombic efficiency (η%) increases with the applied current density reaching 174.5% at 10 A/g. Besides, Ni-Co-P exhibited an outstanding long-term cyclability with enhanced capacitance retention stabilized at around 105% over 1000 cycles at 50 mV/s. This was further evinced from the observed significant decrease in the electrode total resistance after cycling. The study points to the viability of EE method for the successful low-cost synthesis of efficient charge storage materials with excellent stability for high-performance supercapacitor applications.-