SILAR-synthesized Co₃O₄/Bi₂O₃ on copper substrate nanocomposite electrode and asymmetric Co₃O₄/Bi₂O₃/CuO: AC solid-state device in supercapacitor

Hexagonal nanosheets like mesoporous nanostructures were developed on the flexible copper substrate as a binder-free thin-film electrode via a simple and cost-effective successive ionic layer adsorption and reaction (SILAR) technique. Among the numerous deposition techniques available for supercapacitor applications, this one was the most affordable and straightforward. Contact angle examination confirmed the hydrophilic nature of the deposited material. The obtained cobalt oxide/bismuth oxide/copper oxide electrode exhibited a notable specific capacitance (SC) of 1777.12 F/g at 2 mV/s in 1 M KOH and cycling stability (83.53% capacity holding after 5000 cycles). Furthermore, the asymmetric solid-state supercapacitor device assembled with cobalt oxide/bismuth oxide/copper oxide as a positive thin-film electrode and activated carbon (AC) as a negative thin-film electrode demonstrated a high specific energy (SE) of 20.46 Wh/kg at a specific power (SP) of 5640 W/kg and outstanding cycling stability (89.05% retained after 5000 cycles). As a consequence, it showed that the cobalt oxide/bismuth oxide/copper oxide synthesized by the SILAR technique could be a promising thin-film electrode for asymmetric solid-state supercapacitor devices with high energy density and power density.