Synchronous-ultrahigh conductive-reactive N-atoms doping strategy of carbon nanofibers networks for high‐performance flexible energy storage

Flexible carbon nanofibers networks (FCNNs) play a crucial role in flexible and portable energy storage devices. Doping conductive and reactive N-atoms can enhance charge transport and transfer properties vital for high energy storage and high power. However, synchronous-ultrahigh conductive-reactive N-atoms doped FCNNs (SH-FCNNs) are still challenged by the N-atoms instability at high temperatures. To resolve this problem, an in-situ synergistic-carbonization-nitridation strategy is reported using polyaniline (PANI) implanted highly porous polyacrylonitrile nanofibers as a precursor. The obtained SH-FCNNs were doped with 5.9 at% conductive and 4.73 at% reactive N-atoms. They exhibit a superhigh specific capacitance (580.9 F g−1@0.5 A g−1) and high-rate capability (307.2 F g−1@128 A g−1). The flexible solid-state supercapacitors can output specific energy and power density of 18.3 Wh kg−1 and 16.9 kW kg−1. As for flexible solid-state Zn-ion batteries, the constructed SH-FCNNs@PANI cathodes have specific energy (290 Wh kg−1@0.159 kW kg−1) and supercapacitor-like power performance (128.1 Wh kg−1@23.3 kW kg−1). The synergistic effects of ultrahigh conductive and reactive N-atoms promote these performances to reach the mountaintop of flexible solid-state energy storage devices. The novel strategy also presents new insights on designing high-performance FCNNs for electrochemical energy storage, catalysts, and sensors.