Flexible, Self-supporting PVA/Sodium Lignosulfonate/Polypyrrole Composite Electrospun Film as Electrode Material for Supercapacitors.

Flexible, highly conductive, and finely structured conductive materials hold significant promise for applications in flexible supercapacitors. However, the loading effect of conductive active substances and structural design remain critical factors that limit the performance of flexible conductive materials. In this study, polyvinyl alcohol/sodium lignosulfonate (PVA/LS) electrospun films are fabricated and polypyrrole (PPy) particles are loaded onto the surface of the electrospun fibers through in-situ polymerization. By leveraging the abundant sulfonic acid groups in LS, the adsorption force between electrospun fibers and PPy is significantly enhanced. This enhancement ensures the formation of uniform and continuous PPy shell that endows the electrospun film with high conductivity and exceptional electrochemical performance. Furthermore, a stacking method is employed to transform the PVA/LS/PPy film into a three-dimensional thick structure, which significantly increases the areal capacitance. With four layers of stacking, the areal capacitance of the symmetric solid-state supercapacitor assembled by 4(PPy6) reaches 2629.65 mF cm^-2, which is an impressive increase by a factor of 4.64 compared to the single-layer PPy6. This work presents a simple yet effective approach for preparing self-supporting flexible conductive materials with fine microstructures. Consequently, it provides valuable insights for performance improvement of flexible energy storage devices.