Strategic Enhancement of Interfacial Effects in O/S Self-Doped Lignin-Derived Carbon Aerogels with Ultrahigh Specific Surface Area for Superior High-Rate Energy Storage Performance

Abstract

The charge transfer behavior and interfacial interaction between electrode materials and electrolytes are critical for the efficient performance of supercapacitors. Carbon aerogels have garnered significant interest as electrode materials due to their tunable pore structures and high specific surface areas (SSA). Herein, we demonstrate an effective strategy for enhancing interfacial effects between carbon aerogel electrodes and electrolytes through the comprehensive utilization of all components present in black liquor. Hierarchical porous lignin-derived carbon aerogels (BLCAs) with ultrahigh SSA and oxygen/sulfur self-doping was prepared by sol-gel synthesis, pre-carbonization and activation. The formation of a porous lignin hydrogel, achieved through the cross-linking of black liquor, ensures robust mechanical strength and the development of an extensive pore structure. The synthesized BLCA-750 exhibits a hierarchical porous structure incorporating microporous, mesoporous, and macroporous, achieving an ultrahigh SSA of 3776 m2 g−1, alongside moderate oxygen/sulfur self-doping (O: 8.55%, S: 0.64%). As an electrode material, BLCA-750 displays an outstanding specific capacitance of 640.7 F g−1 at a current density of 0.5 A g−1 and demonstrates exceptional cycling stability, retaining 99% of its capacity after 10,000 cycles. Additionally, BLCA-750 achieves the highest energy density of 59.6 Wh kg−1 at a power density of 226 W kg−1. Moreover, MD simulation and DFT calculations elucidate that BLCA-750, with its ultrahigh SSA and O/S self-doping, exhibits substantial charge transfer behavior and strong interfacial interactions with the electrolyte, further confirming its superiority as an energy storage material.

Keywords: Lignin carbon aerogel, Black liquor, Tunable hierarchical pore structures, Oxygen/Sulfur self-doped strategy, Interfacial effect