Synergistic Enhancement of Electrochemical Performance in Lignin-Based Carbon Aerogel Supercapacitors through Phytic Acid-Induced Spherical Structure Formation and Dual P/S Heteroatom Doping

The widespread deployment of renewable energy sources worldwide, such as wind power and photovoltaics, has created an urgent need for efficient energy storage systems. Biomass-derived carbon aerogels, due to their environmentally friendly and sustainable properties, have emerged as ideal precursor materials for advanced energy storage applications, particularly in supercapacitors. This study developed a method to prepare phytate-induced phosphorus/sulfur (P/S) co-doped magnesium lignosulfonate-based carbon aerogels (LCAs). Phytate induction facilitated the formation of regular spherical structures while simultaneously optimizing surface morphology and enabling efficient and uniform doping of P and S heteroatoms. The optimized sample, LCA-2-700, the lignin-based carbon aerogel that was prepared with the magnesium lignosulfonate (LS)꞉sodium alginate (SA)꞉phytic acid (PA) mass ratio of 5꞉5꞉2 and carbonized at 700 °C, exhibited a specific capacitance of 362 F/g at the current density of 0.5 A/g, with the assembled device achieving an energy density of 40.1 W·h/kg at a power density of 700 W/kg. After 20 000 cycles, the capacitance retention rate remained at 82.5%, demonstrating excellent electrochemical durability. The high performance was attributed to the synergistic effects of its spherical structure, high specific surface area, and P/S dual-heteroatom doping. This study provides an effective approach for synergistic structure-doping regulation of lignin-based carbon aerogels and provides a potential pathway for practical applications in high-performance supercapacitors.