Spray drying-assisted co-activation of lignin-derived porous carbon using potassium hydroxide and potassium carbonate for enhanced supercapacitor performance

The increasing demand for sustainable and high-power supercapacitors has driven the search for biomass-derived carbon materials with controllable pore architectures. This work represents the first report on the use of a spray drying-assisted co-activation method to synthesize porous carbon materials derived from lignin, potassium hydroxide (KOH), and potassium carbonate (K 2 CO 3 ). The influence of the K 2 CO 3 /KOH mass ratio and carbonization temperature on particle morphology, pore characteristics, and electrochemical performance was investigated. The combination of KOH and K 2 CO 3 offers a promising co-activation strategy that balances micropore generation and mesopore enlargement, thereby enabling precise control over pore size distribution and achieving hierarchical micro-mesoporous structures. The optimized porous carbon samples were employed as supercapacitor electrodes, delivering a high specific capacitance of 293.1 F/g (three-electrode system) and 123.8 F/g (two-electrode system) at 0.5 A/g. The electrodes also exhibited excellent rate capability (retaining 78% capacitance at 5 A/g), and stable cycling performance (preserving 80% capacitance after 10,000 cycles). These superior properties are attributed to the synergistic pore network and surface oxygen functionalities that enhance ion accessibility and wettability. Moreover, compared to conventional activation methods, the reduced KOH usage highlights the eco-efficiency of this process, enabling sustainable synthesis of high-performance lignin-derived porous carbons for future supercapacitor technologies.