Facile synthesis of N-doped lignin-based carbon nanofibers decorated with iron oxides for flexible supercapacitor electrodes

Abstract

Flexible films of N-doped porous iron oxides/lignin-based carbon nanofibers (CNF@Fe-N) were fabricated and employed for high-performance supercapacitor electrode materials. The CNF@Fe-N films were synthesized through a simple and effective method, which was carried out by an electrospinning technique from lignin/Hemin mixed solution and followed by carbonization. In situ growth of iron oxides on the surface and interior of carbon nanofibers contribute to enhancing the capacitive performance through inducing pseudocapacitance. In the unique structure, the fibrous network structure with rich micropores provides plenty of channels for transportation and penetration of electrolyte ions. The obtained CNF@Fe-N binder-free electrode exhibits a high gravimetric capacitance of 148. 1 F g−1 and high energy density of 12.28 W h L-1 at 0.5 A g−1, as well as an excellent cycling stability with 92.8% capacitance retention after 5000 charge/discharge cycles. The material also presents an outstanding flexibility and folding resistance. The low-cost and renewable sources, easy preparation and remarkable supercapacitive property render CNF@Fe-N a promising candidate in energy storage applications.