Scalable Polymerization Approach to Tailoring Morphologies of Polyimide-Derived N-Doped Carbons for High-Performance Supercapacitors

3D N-doped carbon nanobelt (NCB) networks are fabricated by one-pot hydrothermal polycondensation of co-monomer salts of dianhydride and diamine followed by carbonization of the resulting nanobelt-like polyimides. As control samples, solvothermally polymerized petal-like polyimides and conventionally polymerized spindle-like polyimides are also produced, which further yields N-doped carbon petals and N-doped carbon spindles after identical carbonization, respectively. Interestingly, all N-doped carbons copy the morphologies of their polyimide precursors well. Specially, the 800 degrees C-treated NCB exhibits a robust 3D architecture composed of intertwined nanobelt networks with high N-doping levels and electroactivity-enriched N configurations. Remarkably, the symmetric supercapacitor assembled by such NCB electrodes delivers large specific capacitance (193 F g(-1) at 1 A g(-1)), high rate capability (176 F g(-1) at 20 A g(-1)), and long cycling stability (nearly 100% retention over 10,000 cycles at 20 A g(-1)). The energy density is as high as 27 Wh Kg(-1) at the power density of 500 W Kg(-1), and retains 24 Wh Kg(-1) at the power density up to 20,000 W Kg(-1). This work opens up an affordable and scalable approach to the rational fabrication of heteroatom-contained carbon materials for high-performance supercapacitors with well-balanced power and energy output.