Laser synthesis of superhydrophilic O/S co-doped porous graphene derived from sodium lignosulfonate for enhanced microsupercapacitors

Porous graphene with rational heteroatoms doping has been widely researched as one of the most prominent materials for application in supercapacitors. Herein, we implement a green and facile laser engraving strategy to synthesize three-dimensional (3D) superhydrophilic and oxygen (O)-sulfur (S) co-doped porous graphene electrodes. Specifically, the mixed sodium lignosulfonate slurry is evenly coated on the laser-induced graphene (LIG) interdigital electrodes, and followed by a duplicated laser scribing process. The as-prepared materials can synchronously possess hierarchical porous graphene architectures, superior hydrophilicity, and O/S co-doped chemistry properties, which can significantly promote the penetration and transport of electrolyte ions and provide extra pseudocapacitance. Benefiting from these advantages, satisfactory capacitive performance of the assembled MSCs is obtained, such as an outstanding areal capacitance of 53.2 mF cm-2@0.08 mA cm-2, which is about 39 times larger than of undoped MSC. Moreover, remarkable mechanical flexibility, excellent modular integration capability as well as good cycling stability (81.3% capacitance retention after 8000 cycles) have been also achieved. As such, this study offers a novel and efficient strategy for valuable utilization of biomass lignosulfonate, and the as-prepared heteroatom-doped superhydrophilic porous graphene holds enormous promise for high-performance energy storage devices.