Heterostructures of two-dimensional dense PEDOT:PSS film and three-dimensional interconnected PEDOT:PSS network assembled by nitrogen-doped carbon fiber framework for high-performance supercapacitors

Two combined structures of two-dimensional (2D) dense films and self -assembled three-dimensional (3D) interlayers of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) were fabricated via a one-step tape -casting method using a nitrogen -doped carbon nanofiber (NCNF) membrane as a framework substrate for hybrid membrane electrodes. The synergistic contribution of the highly conductive PEDOT:PSS, pseudocapacitive conductive NCNF framework, and unique hybrid microstructure with the hierarchical complex structures of the PEDOT:PSS/NCNF composite guarantees the fast diffusion of electrolyte ions through the electrode. When tested as a hybrid electrode in a three -electrode configuration, the 2D/3D heterostructured electrode of the PEDOT:PSS/NCNF composite fabricated by tape casting (t-PPF/NCNF) showed a high specific capacitance of 641 F g -1 at 1 A g -1 and a good rate capability with an approximately 74 % capacitance retention from 1 A g -1 to 30 A g -1 , which is superior to those of the single -component PEDOT:PSS film, NCNF membrane, and binary components of self -assembled 3D homostructured electrodes prepared by the dip -coating method (d-PPF/NCNF). More notably, a symmetric supercapacitor device composed of two identical hybrid electrode films with the 2D/ 3D heterostructured t-PPF/NCNF electrode demonstrated a maximum energy density of 52.4 Wh kg -1 at a power density of 771.7 W kg - 1 and a maximum power density of 16.8 kW kg - 1 at an energy density of 18.4 Wh kg - 1 with a voltage of 1.5 V, while retaining outstanding cycling stability (91 % capacitance retention after 2000 cycles at 5 A g -1 ), indicating a promising potential for the development of high-performance hybrid supercapacitors.