Lignosulfonate-Assisted Synthesis of Porous Carbon-Supported MnO₂ Composites with Reinforced Interface Bonding for High-Performance Asymmetric Supercapacitors

Abstract

Carbon/transition metal oxide composites exhibit promising potential as electrode materials for energy storage, but regulating their interfacial composite structures remains a formidable challenge. In this work, we develop a lignosulfonate-assisted synthesis strategy to fabricate a porous carbon-supported MnO 2 composite (LSC/MnO 2 -2) with a robust interface for asymmetric supercapacitors (ASCs). The functionalized lignin porous carbon, achieved through π−π interactions with lignosulfonate, exhibited improved dispersibility, thereby facilitating the deposition of MnO 2 onto the carbon matrix. Consequently, LSC/MnO 2 -2 demonstrates uniform MnO 2 loading and enhanced interfacial bonding. The robust interaction between Mn sites and the lignosulfonate-functionalized carbon substrate can promote electron transfer and ion transfer kinetics, effectively activating the electrochemical activity of MnO 2 . The as-prepared LSC/MnO 2 -2 demonstrates high specific capacitances of 750 F/g at 0.5 A/g and 400 F/g at 10.0 A/g in a 1 M KOH electrolyte. Furthermore, the assembled ASC exhibits an outstanding energy density of 54.4 Wh/ kg at 998.2 W/kg and excellent cyclic stability (94.7% retention over 10,000 cycles at 2.0 A/g). This study presents an alternative method to precisely control the deposition of metal oxides onto carbon materials, aiming to enhance the performance of carbon composites.