Nitrogen-Doped Carbon Composites Embedded with Cu/Co Species Derived from Metal-Functionalized Ionic Liquids: Design and Supercapacitive Performance

Although traditional carbon-based supercapacitor electrode materials exhibit good cycling stability and conductivity, their specific capacitance and energy density are limited by the dual-layer capacitor storage mechanism, making it difficult to satisfy the growing demand for high-performance energy storage. Consequently, the introduction of pseudocapacitive materials with Faradaic charge transfer characteristics has become a research focus in the field of supercapacitors. Herein, Cu/Co metal-anchored carbon composites (IL-Cu@NC and IL-Co@NC) have been successfully synthesized using metal-functionalized ionic liquids as both precursors and dopants via a one-step carbonization process. The micro-morphology, crystallinity, surface chemical states, and pore structure of the prepared electrode materials have been systematically characterized using scanning electron microscopy (SEM), chronoamperometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and N2 adsorption–desorption measurements. The energy storage performance of the fabricated electrode materials has been investigated using a three-electrode system in an alkaline solution. The optimized IL-Cu@NC electrode achieves a specific capacitance of 653 F g−1 at 0.5 A g−1, along with stable cycling performance. This research proposed a feasible strategy for developing high-performance supercapacitor electrodes by functionalizing metals with ionic liquids, achieving enhanced specific capacitance compared with conventional carbon materials.