Sodium lignosulfonate and KOH dual-activated N/O/S Co-doped microporous-mesoporous carbon for high-performance supercapacitors

Biomass-derived porous carbon holds great promise as an electrode material for supercapacitors due to its low cost and sustainability. However, single-activator strategies typically fail to achieve microporous-mesoporous structure with high specific surface area (SSA) and micropore volume of such carbon materials, thereby limiting their capacitive performance. Therefore, inspired by the pyrolysis behavior of sodium lignosulfonate, we innovatively propose a novel activation system for preparing N/O/S co-doped biomass microporous-mesoporous carbon (SLCA): utilizing chitosan carbon and sodium lignosulfonate as self-doping carbon sources, potassium hydroxide as the primary activator, and sodium lignosulfonate as the self-templating activator. The microporous volume is a key factor influencing specific capacitance. Specifically, the SLCA-700 (activated at 700 °C) has a microporous-mesoporous structure with abundant N/O/S heteroatoms doping and a SSA of 2378.7 m 2 ·g −1 , and achieves a high micropore volume of 0.84 cm 3 ·g −1 , which is 0.24 cm 3 ·g −1 higher than that of the KOH activation system alone. Furthermore, the SLCA-700 electrode exhibits an outstanding specific capacitance of 305.9 F·g −1 at 0.5 A·g −1 , and supercapacitor shows excellent cycling stability (97.0% capacitance retention after 10,000 cycles). This study proposes a dual activation mechanism for preparing microporous-mesoporous carbon with a high SSA, providing a viable strategy for producing high-performance supercapacitor electrode materials.