Polyacrylonitrile-Derived Porous Carbon with Embedded Carbon Nanotubes for All-Carbon Asymmetrical Supercapacitors

The low energy density and mismatched electrode kinetics of conventional asymmetric supercapacitors (ASCs) greatly limit their practical commercial applications. To address these problems, here, a nitrogen-doped polyacrylonitrile-derived porous carbon embedded with carbon nanotubes (N-doped PC/CNTs) is prepared using a simple and scalable blade-coating and carbonization method and used to fabricate high-performance all-carbon asymmetric supercapacitors. The N-doped PC/CNT composites deliver a large specific surface area (SSA) and high degree of graphitization. Electrochemical tests show that the PC/CNT composite displays different capacitance performances in different potential windows, achieving gravimetric capacitances of 286.3 and 178.1 F g–1 within operating windows of –0.8 to 0 V and 0 to 0.8 V, respectively. Based on these properties, an assembled all-carbon ASC delivers a wide voltage window of 1.6 V, achieving a maximum operating window of 1.6 V, a maximum energy density of 24.4 Wh kg–1, and maintains 15.2 Wh kg–1 even at a high-power density of 40 kW kg–1. Moreover, the capacitance retention remains above 90% after 20,000 cycles, showing favorable potential for advanced electrochemical energy storage.