Three-dimensional, heteroatom-enriched, porous carbon nanofiber flexible paper for free-standing supercapacitor electrode materials derived from microalgae oil

Polyacrylonitrile (PAN) based carbon nanofiber (CNF) papers have unique physicochemical properties including flexibility, good electrical conductivities, and excellent mechanical properties for supercapacitor electrodes. However, their surface-to-weight ratios and density of active sites on the surface are much poorer than those of other active carbons. Herein, a simple, renewable, multifunctional, and effective way is described to fabricate three-dimensional (3D) heteroatom-enriched porous PAN-based CNF papers by adding a moderate amount of microalgae-derived oil that has a large fraction of light compounds and nitrogen- and oxygen-containing functional components. CNF papers with enhanced porosity and large specific surface area, unique pore structure, and 3D heteroatom-enriched surfaces were successfully fabricated by stabilization and carbonization of PAN nanofibers with the algae oil. The as-fabricated algal-30% CNF paper is scalable and highly flexible as a free-standing supercapacitor electrode material and can deliver a specific capacitance of 272 F/g under a scan rate of 10 mV/s with noticeably high charge-discharge cycling stability, with 94% retained even after 10,000 cycles. The fabrication mechanism and the enhancement of the electrochemical behaviors of three-dimensional, heteroatom-enriched, porous CNF papers are proposed. Our work underlines the promise of algae oil-modified PAN-based CNF papers for high-capacity supercapacitor electrode materials.