Ni/MnO2 doping pulping lignin-based porous carbon as supercapacitors electrode materials

Abstract Lignin extracted from pulping black liquor as carbon source, C4H6O4Ni·4H2O as acatalyst and KMnO4 as dopant, a lignin-based porous carbon material (PC-Ni/MnO2) co-doped with Ni and MnO2 was prepared and used in electrode materials for supercapacitors. During the high-temperature carbonization process, part of amorphous carbon generates a multi-layer graphene structure, causing the PC-Ni/MnO2 to has a high degree of graphitization. Meanwhile, KMnO4 gradually decomposes and reacts with C to produce MnO2. The lignin-based porous carbon material has a higher pseudocapacitance, the specific capacitance of PC-Ni/MnO2 can reach 267.34 F g−1 at a current density of 0.1 A g−1. After 5 000 cycles charge and discharge test, the specific capacitance retention rate kept 83.6% at a current density of 1 A g−1, showing good rate performance and electrochemical stability. A symmetrical supercapacitor prepared by PC-Ni/MnO2 as electrodes, its energy density can reach 28 Wh·kg−1 as the power density of the capacitor is 360 W kg−1. And the supercapacitor also exhibited good cyclic stability with 86.3% retention of initial capacitance after 5000 cycles at 1.0 A g−1. When two such supercapacitors in series, a LED lamp can be light. These induct that the doping of Ni and MnO2 can improve the capacitance characteristics, showing that the biomass porous carbon has great practical application value.