Controllable Preparation of Cu NPs/CNTs@PANI Composites as Electrode Materials for Electrochemical Double-Layer Capacitors

Copper nanoparticles are uniformly supported on acidified carbon nanotubes (CNTs/Cu NPs) by a mild liquid-phase reduction method without surfactants or bridging molecules. The surface of copper nanoparticles is smooth without impurities. Then, polystyrene (PS) microspheres are prepared by emulsion polymerization and composited with CNTs/Cu NPs (CNTs/Cu NPs/PS). Nanocopper/carbon nanotubes as the core and polyaniline as the shell were prepared via situ polymerization as a core–shell structure (PANI@CNTs/Cu NPs/PS). At a high temperature, the PS cracks and eliminates materials, forming porous structures, and the polyaniline is carbonized, realizing nitrogen doping of the material (NCMP). The results indicated that the acidified carbon nanotubes played a crucial role in the synthesis procedure, achieving consistent growth of copper on carbon nanotubes. The size of evenly dispersed copper nanoparticles is about 5–15 nm. When NCMP is applied as an electrode material, it demonstrates excellent electrochemical performance as a high-performance supercapacitor.