Development of binder-free, amorphous nickel vanadate cathodes by SILAR method for hybrid supercapacitors: Exploiting surface area by monitoring growth rate

Developing self-supported electrode material in the absence of electro-inert binders considering the effortless transfer of charges and manipulating physicochemical properties of electrodes in energy storage devices is essential. Hence, the present attempt emphasizes the facile synthetic strategy of successive ionic layer adsorption and reaction (SILAR) for controlled nickel vanadate (NV) growth over the conducting plate. In SILAR synthesis, the growth rate is monitored by rinsing and adsorption/reaction time variation to tune the surface area, mesoporous structure, and surface morphology of NV thin films. As a result, the formation of mesoporous, amorphous, hydrous nanoparticles of NV over the stainless-steel substrate is affirmed by structural analysis. Furthermore, alteration in specific surface area with variation in growth rate is observed in BET analysis. As a result, the optimal NV(1:2) thin film electrode exhibited the highest specific capacity (capacitance) of 355C g-1 (710 F g-1) at 1 A g-1 current density. Moreover, the fabricated aqueous hybrid supercapacitor device (NV (1:2)//rGO) delivered 109 F g-1 specific capacitance at 1.3 A g-1 current density, and the device exhibited a maximum specific energy (SE) of 44 Wh kg- 1 at a particular specific power (SP) of 1.14 kW kg- 1. Furthermore, the solid-state hybrid supercapacitor (NV(1:2)//PVA-KOH//rGO) device conferred a specific capacitance of 89 F g-1 at 0.5 A g-1 current density and an SE of 36 Wh kg- 1 at 0.482 kW kg- 1 SP. This research paved an avenue to the binder-free, scalable synthesis of NV electrodes and employed them as a cathode in practical applications of hybrid energy storage devices.