Controllable synthesis of cyano-rich porous carbon for flexible all-solid-state supercapacitors with wide potential

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Porous carbon has attracted extensive attention as electrode material of energy storage devices due to its rich porosity, large specific surface area, and facile availability. However, controlled preparation of porous carbon with targeted functional groups remains a great challenge. Herein, we demonstrate a facile and controllable synthesis of porous carbon with abundant functional groups through a small molecule-based approach. With glyoxal and acrylonitrile as raw materials, the hydrothermal reaction and subsequent activation with KOH resulted in the porous carbon with abundant cyano (–CN) and hydrophilic groups, which shows strong electronegativity and can coordinate with K ions to enhance charge storage ability. Due to the combined effect of the three-dimensional (3D) porous structure, abundant favorable functional groups, as well as good electrical conductivity, the optimized sample (PCCN-K700) exhibited high specific capacitance of 245.6 F/g at 1 A/g (which is 12 times that of unactivated sample) and excellent cycling stability with 98.5 % capacitance retention after 5000 cycles at 5 A/g. In addition, the flexible all-solid-state supercapacitor assembled with PCCN-K700 showed excellent flexibility and wide voltage window (up to 1.6 V). With bending angle varying from 0° to 150°, no obvious degradation in electrochemical performance was observed. This work provides a facile and promising small molecule-based approach for the fabrication of porous electrode materials with abundant functional groups for high-performance supercapacitor.