High-areal-capacitance electrode constructed by lignin-based microporous carbon nanofibers for supercapacitors

Self-supporting three-dimensional fiber network derived from electrospinning technology is an ideal structure for constructing high-loading thick electrodes. In this work, microporous carbon nanofiber membranes (MCNMs) are prepared by electrospinning using lignin as precursor and TEOS as additive. The introduction of TEOS plays a crucial role in producing abundant micropores and improving the thermal stability of fibers. With the aid of TEOS, the obtained lignin-based MCNMs present a high specific surface area of 1197 m2 g−1, microporosity of 84.1 % and notably-enhanced diameter retention rate. With excellent flexibility and satisfactory strength, the lignin-based MCNMs exhibit an impressive specific capacitance of 282 F g−1 at 0.2 A g−1 when used as a self-supporting electrode for supercapacitors. By layer-by-layer stacking of the lignin-based MCNMs, thick electrode is constructed and presents an areal capacitance of 5.72 F cm−2 at mass-loading of 25.4 mg cm−2. Further, the supercapacitor assembled by thick electrodes exhibits an areal power density of 0.54 mW cm−2 and energy density of 0.08 mWh cm−2 at low rate, and 54 mW cm−2 and 0.03 mWh cm−2 at high rate. With merits of renewable raw materials, unsophisticated process, and prominent performance, the lignin-based MCNMs provide a promising alternative electrode material for supercapacitors.