In Situ Polymerization of PANI to Uniformly Coat Lignin-Based Carbon Fibers for High-Performance Supercapacitors

Lignin is abundant and renewable, and its high-value utilization in carbon-based supercapacitor electrodes has attracted considerable attention. However, pure lignin-based carbon fibers (LCFs) have insufficient active sites, and direct loading of polyaniline (PANI) easily causes agglomeration, limiting their electrochemical performance. In this work, LCFs were prepared from lignin and polyacrylonitrile (PAN) via electrospinning, preoxidation, and carbonization, and were then combined with PANI through three different methods to systematically compare their effects on the composite properties. Results show that in situ polymerization achieves a uniform PANI coating on LCFs, alleviating agglomeration. The Is-LCFs-PANI-3 sample exhibits a specific capacitance of 287.36 F g –1 at 0.5 A g –1 , with 86% retention after 3000 cycles. The assembled symmetric supercapacitor has a device capacitance of 69.02 F g –1 and 78% retention after 3000 cycles. This work provides a route for the high-value utilization of lignin and the development of high-performance supercapacitor electrodes.