Flexible lignin-derived carbon nanofiber substrates functionalized with iron (III) oxide nanoparticles as lithium-ion battery anodes

To develop high-performance flexible anodes has become an emerging technological demand for the next generation of lithium-ion batteries (LIBs). In this study, flexible substrates consisting of randomly overlaid electrospun carbon nanofibers (ECNFs) with fiber diameters of ∼200 nm and BET specific surface area of ∼583 m2∙g−1 were made from lignin and polyvinyl alcohol by electrospinning followed by stabilization in air and carbonization in argon. After surface-functionalization with Fe2O3 nanoparticles, the resulting flexible ECNF/Fe2O3 nanostructures/electrodes exhibited enhanced lithiation/delithiation performance. Specifically, in lithium-ion half-cells with ∼35 wt% Fe2O3 nanoparticles deposited on ECNF surfaces, the discharge capacities of ∼951 mA∙h∙g−1 in the first cycle and ∼715 mA∙h∙g−1 after 80 cycles were observed. This study presents a new approach for the fabrication of flexible LIB anodes by eliminating commonly used organic binders, metal substrates, and electrode slurries; furthermore, lignin that is a waste byproduct of cellulose industry has been successfully utilized in this approach.