Transforming kraft lignin into supercapacitor electrodes via graphene oxide assisted co-pyrolysis and activation

Kraft lignin, the most abundant aromatic biopolymer and a major by-product of the pulp and paper industry, is commonly regarded as low-value waste and typically discarded or burned. Unlocking its potential as a renewable carbon feedstock remains a pressing challenge for energy storage applications. Here, we present a strategy to upcycle kraft lignin into supercapacitor electrodes through graphene oxide (GO) assisted co-pyrolysis and followed high-temperature activation. Lignin facilitates the dispersion and reduction of GO, while lignin-derived porous carbon frameworks suppress reduced GO restacking. In turn, the reduced GO effectively prevents the collapse of the lignin-derived carbon skeleton and constructs an efficient charge transport architecture. Carbon electrodes with hierarchical porous architecture and interconnected conductive pathways delivers a high specific capacitance of 347.2 F g⁻¹ and an areal capacitance of 694.3 F cm⁻². The assembled symmetric supercapacitors exhibit an energy density of 26.1 Wh kg⁻¹ and retain 90.5 % capacitance after 5000 cycles. This approach not only transforms lignin into advanced carbon materials but also establishes a paradigm of co-evolution between biomass-derived frameworks and two-dimensional nanomaterials for sustainable energy storage technologies. • Upcycling lignin into high-performance carbon electrodes for supercapacitors. • Graphene oxide assisted co-pyrolysis and activation strategy. • Hierarchical porous architectures and conductive networks. • The symmetric supercapacitor exhibits the energy density of 26.1 Wh kg -1 .