Deep eutectic solvent assisted zero-waste electrospinning of lignin fiber aerogels

We developed a novel electrospinning strategy, using choline chloride–lactic acid (ChCl–LA) deep eutectic solvent (DES) as an electrospinning solvent to produce lignin fiber aerogels (LFA). The novel strategy is sustainable and cost-effective because no toxic or flammable volatile organic solvents were used and the precursors and waste were designed to be recycled. The fabricated LFA has the appearance of a piece of cotton, and the specific mass was calculated and found to be as low as 3 mg cm−3 with a porosity of over 99.7%. After stabilization and carbonization at a high temperature, the LFA can transform into lignin-based carbon fiber aerogels (LCFA). The LCFA has a high specific surface area (580 m2 g−1) and conductivity, and can be used as an electrochemical electrode material. We made supercapacitor electrodes using the LCFA, the specific capacitance of which is 155 F g−1, much higher than that of commercial multi-wall carbon nanotubes (39 F g−1) at a current density of 0.5 A g−1. The LCFA also have a high electrochemical cycling stability. For the supercapacitor electrodes, only a 2% decrease was observed after 5000 cycles. Moreover, all waste in this work was recycled and reused five times to achieve electrospinning with almost no waste.