A High‐Energy Density Asymmetric Supercapacitor Based on Fe₂O₃ Nanoneedle Arrays and NiCo₂O₄/Ni(OH)₂ Hybrid Nanosheet Arrays Grown on SiC Nanowire Networks as Free‐Standing Advanced Electrodes

Abstract In this paper, a novel freestanding core‐branch negative and positive electrode material through integrating trim aligned Fe₂O₃ nanoneedle arrays (Fe₂O₃ NNAs) is first proposed with typical mesoporous structures and NiCo₂O₄/Ni(OH)₂ hybrid nanosheet arrays (NiCo₂O₄/Ni(OH)₂ HNAs) on SiC nanowire (SiC NW) skeletons with outstanding resistance to oxidation and corrosion, good conductivity, and large‐specific surface area. The original built SiC NWs@Fe₂O₃ NNAs is validated to be a highly capacitive negative electrode (721 F g⁻¹ at 2 A g⁻¹, i.e., 1 F cm⁻² at 2.8 mA cm⁻²), matching well with the similarly constructed SiC NWs@NiCo₂O₄/Ni(OH)₂ HNAs positive electrode (2580 F g⁻¹ at 4 A g⁻¹, i.e., 3.12 F cm⁻² at 4.8 mA cm⁻²). Contributed by the uniquely engineered electrodes, a high‐performance asymmetric supercapacitor (ASC) is developed, which can exhibit a maximum energy density of 103 W h kg⁻¹ at a power density of 3.5 kW kg⁻¹, even when charging the device within 6.5 s, the energy density can still maintain as high as 45 W h kg⁻¹ at 26.1 kW kg⁻¹, and the ASC manifests long cycling lifespan with 86.6% capacitance retention even after 5000 cycles. This pioneering work not only offers an attractive strategy for rational construction of high‐performance SiC NW‐based nanostructured electrodes materials, but also provides a fresh route for manufacturing next‐generation high‐energy storage and conversion systems.