Self‐Supported SiC@Graphene Porous Array Electrodes for Ultrastable Supercapacitors

ABSTRACT Silicon carbide (SiC) single crystals have significant potential in high‐temperature integrated power systems due to their outstanding electron mobility and heat resistance. However, slow charge storage dynamics and insufficient energy density are the bottlenecks for their practical application in supercapacitors. In this paper, nanoscale SiC nanochannels were achieved by regulating KOH concentration, current density, and steam etching parameters in a steam‐assisted anodic etching process. The specific surface area and ion‐diffusion kinetics were significantly enhanced by this nanostructure. Subsequently, continuous covalently bonded graphene layers (SiC@G) were grown through high‐temperature pyrolysis, constructing self‐supporting high‐temperature electrodes for high‐temperature supercapacitors. The experimental results demonstrate that this integrated structure featuring a SiC–graphene heterointerface affords abundant active sites, enhances electrical properties, preserves the crystal structure from degradation, and improves structural stability. The composite electrode exhibits excellent electrochemical performance in ionic liquid electrolytes: The energy density reaches 4.9 μWh cm −2 at 150°C, and the capacity retention rate is 89.55% after 10,000 cycles. This work confirms the significant potential of SiC/graphene composites as electrodes in supercapacitors, providing a new design strategy for high‐temperature energy storage devices based on wide‐bandgap semiconductors.