Anode, as a constituent element of a battery is the crucial component for battery’s cycle life and rate capability. Anodes with different zero-, 1D-, 2D- and 3D nanostructures made of different materials have been proposed. Among them 1D carbon nanofibers (CNF) can provide shorter lithium ion diffusion lengths, electron transport and enhanced surface area. The possibility for adding different active materials into their structure and their usage as free standing electrodes are another advantages of CNF. Another approach to improve battery performances increasing their surface area by activating the carbonaceous material.

Lignin is abundant low-cost polymer obtained from a variety of biomasses by solvent extraction as most common method. As a byproduct of paper industry it can be used as fuel additive, emulsifier or dispersant in agriculture, as binder or reinforcement in different composite structures, as antioxidant for polymers. Due to its highly functionalized macromolecules can be used as starting material for renewable polymers, such as polyesters, polyurethanes or polyanilines. Besides, its high carbon content allows its usage as precursor polymer for carbon production. As non-toxic and biocompatible polymer is promising precursor to replace PAN in carbon fiber production. However, its low molecular weight is an obstacle for its conversion into nanofiber. One approach to overcome this problem is blending it with high molecular weight polymers, such as poly (vinyl alcohol), polyethylene oxide, poly acrylonitrile, polyethylene glycol, polypropylene, etc.

In this study, lignin/PVA blends were converted into nanofibers by electrospinning. The fibrous structure was further stabilized under iodine vapor and then carbonized in inert atmosphere. Activation of the carbonaceous structure was realized by dissolving the polymers into basic aqueous solution and completed by neutralization with acidic aqueous solution. In order to study the effect of the degree of activation on electrochemical properties, solutions with different KOH concentrations were prepared. As prepared carbon nanofibers were used as free-standing anodes without addition of current collector in a half cell button type Li-ion battery. The change in morphology of the fibers was characterized by SEM, while the change in their chemical structure by RAMAN spectroscopy. Battery rate capability and cycling stability were analyzed by galvanostatic cycling test. The results showed activated lignin-based carbon nanofibers can improve the cycling stability and rate capability when used as anodes in Li-ion batteries.