Synergistic interfacial coupling of zirconium with amino-functionalized lignin for high-performance supercapacitors

Lignin-derived carbon materials exhibit limited electrochemical performance due to their single pore structure, insufficient active sites, and poor conductivity. Herein, an N, P, S co-doped lignin-based electrode (PCLC) was synthesized from camellia seed shell via a “Mannich reaction-Zr coordination-phosphate adsorption” strategy. FTIR, XPS, XRD, SEM-EDS, and N₂ adsorption confirmed successful heteroatom grafting and a 10-fold increase in specific surface area. The PCLC electrode demonstrated enhanced areal specific capacitance (396.14 mF cm −2 at 0.2 mA cm −2 ), surpassing that of the N, S co-doped lignin-based electrode (CLC, 189.06 mF cm −2 ). Dunn and Trasatti analyses attributed this improvement to accelerated ion transfer and increased active sites. When assembled into a symmetric supercapacitors (PCLC//PCLC), it achieved an energy density of 21.99 mWh cm −2 at 100 mW cm −2 , with 92.3% capacitance retention after 10,000 cycles. This work offers a novel pathway for developing lignin-based high-performance supercapacitors.