Layer-by-Layer Assembly of Graphene Oxide and Polyethylenimine on Carbon Nanofiber Films for Supercapacitor Applications

Although lignin-based carbon nanofibers (CNFs) have been successfully applied in the environmental, energy, and aerospace fields, obtaining fibers with excellent electrochemical performance is an urgent problem to be solved. In this work, lignin-based precursor fibers with nanofiber structures are prepared as the basal layer for the layer-by-layer (LbL) assembly of the electroactive substance polyethylenimine (PEI) and graphene oxide (GO) to obtain structured lignin-based CNFs with excellent electrochemical properties. The uniformly distributed multilayered nano-architecture and interconnected network structure provide a high specific surface area and effective contact area, thus promoting ion diffusion and transport and improving the electrical interaction and chemical reactions of the lignin-based CNFs. The specific capacitances and energy densities reach 339.3 F/g and 30.16 Wh/kg, respectively. Furthermore, the lignin-based CNFs exhibit an excellent durability and quick response to temperature (the current changes rapidly in 2 s of temperature rise). This work puts forward a simple and efficient strategy to fabricate nanocomposite fibers with orderly and controllable structures by LbL assembly using lignin-based raw materials. These nanocomposite fibers exhibit great potential for application in supercapacitor, fire alarm, and environment-friendly energy products.