A High‐Energy Density Asymmetric Supercapacitor Based on Fe 2 O 3 Nanoneedle Arrays and NiCo 2 O 4 /Ni(OH) 2 Hybrid Nanosheet Arrays Grown on SiC Nanowire Networks as Free‐Standing Advanced Electrodes

In this paper, a novel freestanding core‐branch negative and positive electrode material through integrating trim aligned Fe 2 O 3 nanoneedle arrays (Fe 2 O 3 NNAs) is first proposed with typical mesoporous structures and NiCo 2 O 4 /Ni(OH) 2 hybrid nanosheet arrays (NiCo 2 O 4 /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@Fe 2 O 3 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@NiCo 2 O 4 /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.