Enhanced potential window of hybrid supercapacitors: nickel–chromium-enveloped cobalt oxide with advanced nanowire-fused microsheet morphology

The goal of intensive energy storage research is to find and create new electrode materials with improved potential windows. In this report, we develop a novel electrode material that combines a characteristic fusion morphology with an enlarged potential window. Using a two-step in-situ growing technique, multilayered nickel–chromium-enveloped cobalt oxide (NiCr@CoO) nanowire-fused microsheets were created on a nickel foam (NF) substrate. The procedure consists of a basic hydrothermal technique after a standard wet chemical method. It was examined and optimized how experimental duration affected the in-situ evolution of morphology. A unique combination of one-dimensional (1D) nanowires and 2D microsheets was demonstrated by the optimized CoO-3h/NF electrode. The NiCr@CoO-3h/NF electrode that resulted from applying an amorphous NiCr layer to the electrode surface showed an extended potential window. In comparison to its antecedent, the NiCr@CoO-3h/NF electrode that was produced by covering the electrode surface with an amorphous NiCr layer enhanced the potential window. For 10,000 charge/discharge cycles, this innovative NiCr@CoO-3h/NF working electrode retained 134.38% cycling retention and attained a remarkable areal capacity of 1019.59 µAh cm−2. The usefulness of the NiCr@CoO-3h/NF was further demonstrated when it was used as the positive electrode in a hybrid supercapacitor (HSC) device. With a maximum energy density of 480.76 µWh cm−2 and a peak power density of 21,600 µW cm−2, the HSC device produced an areal capacitance of 1601.87 mF cm−2. Furthermore, a smart biometric system with a transparent illuminative display mechanism was developed, and the fabricated HSC device was used to drive that system to practically prove its functionality.