Flexible Solid-State Supercapacitors Derived from Biomass Konjac/Polyacrylonitrile-Based Nitrogen-Doped Porous Carbon

Energy shortage and wasting of resources are two main challenges for human society. To solve these problems, nitrogen-doped porous carbon was synthesized through a simple thermally induced phase separation (TIPS) method with subsequent carbonization and activation with biomass konjac/polyacrylonitrile composites as the raw materials and nitrogen source for the first time. The obtained composite carbon with hierarchical porosity, large specific surface areas, and high content of nitrogen doping shows promise due to its desirable electrochemical performance. Nitrogen-doped porous carbon exhibits a high specific capacitance of 390 F g^-1 in a three-electrode system and a good rate characteristic with 70% capacitance retention at 20 A g^-1. Excellent stabilization was observed with only a 4.5% capacitance decay under 10 000 cycles at 5 A g^-1. The practical application of the composite porous carbon on flexible symmetrical supercapacitors was evaluated, showing a maximum energy density of 9.0 W h kg^-1 when the power density was 250.2 W kg^-1. More importantly, the fabricated flexible supercapacitor could still keep an excellent supercapacitor performance under bending and shows only a slight capacitance loss of 9% even after 1000 cycles (180°) of repetitive bending. The current study promotes the development of nitrogen-doped carbon materials on flexible energy storage devices.