Chemical Bath Deposition of Pollen Grain-Like NiS/CoS Heterostructure for Supercapattery With High Areal Capacity

Abstract

Chemical bath deposition (CBD) is a facile technique to coat the substrate with a thin and uniform coating of material with unique morphology. Herein, the CBD method was adopted to fabricate nickel sulfide/cobalt sulfide (NiS/CoS) electrodes for supercapattery application. The NiS/CoS electrodes were fabricated at different deposition times to study the evolution of material morphology with respect to time. Deposition time is a crucial factor in regulating the growth kinetics of the active material to attain the desired morphology for energy storage applications. XRD and X-ray photoelectron spectroscopy (XPS) analysis verified the growth of NiS/CoS nanostructures on the nickel foam (NF) surface. Based on field emission scanning electron microscope (FESEM) micrographs, it was evident that the deposition time of 2.5 h was ideal for maximum coverage of material with spherical thread-like morphology resembling the pollen grains. Correlatedly, the NiS/CoS-2.5 electrode showed the highest specific capacity of 2.60 C cm⁻² at 2.0 mA cm⁻² current density. The optimized electrode was coupled with activated carbon (AC) to fabricate NiS/CoS-2.5//PVA + KOH//AC supercapattery, which sustained 90% of the initial capacity after 2000 continuous cycles at 4.0 mA cm⁻². This study portrays the prospects of CBD as a simple yet reliable approach to developing electrodes with good specific capacity for supercapattery application.