Setaria Viridis-Inspired Electrode with Polyaniline Decorated on Porous Heteroatom-Doped Carbon Nanofibers for Flexible Supercapacitors

Carbon nanofibers are promising as primary electrode materials for supercapacitors on account of high specific surface area, lightweight, superior physicochemical stability, rich resource, and renewability. However, constructing porous and flexible carbon electrode materials with high capacitance for practical applications remains challenging. Here, heteroatom-decorated hierarchical porous carbon nanofiber composites containing phosphazene [N3P3(p-OC6H4-p-CHO)6, HAPCP], polymethyl methacrylate (PMMA), and graphene oxide (GO) are prepared through one-step electrospinning and subsequent thermal treatment. The alternant phosphorus–nitrogen structure links to the carbon backbones to improve flexibility and electrochemical performance. Inspired by a biomimetic Setaria viridis-like structure, the polyaniline (PANI)-decorated porous hybrid electrodes are prepared. The PANI@GO/PMMA/HAPCP/PAN carbon nanofibers (400P@0.1GPHCNFs) covered by PANI nanofibers as a novel free-standing flexible electrode exhibit an excellent electrochemical performance of 680.8 F g–1 at 0.5 A g–1 with a good capacitance retention of 93.5% after 3000 cycles. Moreover, the symmetric flexible all-solid-state supercapacitor assembled by the novel and delicate electrodes exhibits a high energy density of 27.70 W h kg–1 (at a power density of 231.08 W kg–1) and favorable cycling stability (84.50% retention of the capacitance after 1000 charge–discharge cycles), which indicates that the 400P@0.1GPHCNFs have great potential as a high-performance flexible supercapacitor electrode.