Search

Biomass carbon-based MnO electrode materials were synthesized using ramie as the biomass precursor of carbon and potassium permanganate as the precursor of MnO. The ramie-activated carbon/manganese monoxide (RAC/MnO) composite electrodes exhibited a specific capacitance of 720 F/g at a current density of 0.5 A/g. A symmetric cell assembled using the composite electrodes showed a specific capacitance of 45 F/g at 0.5 A/g and an energy density of 12.25 Wh/kg at a power density of 350 W/kg. The excellent electrochemical performance was analyzed by characterizing the electrodes' chemical composition, microstructure, crystal orientation, specific surface area, and pore distribution. Because of the large overpotential of MnO, the composite electrode's working voltage reached 1.4 V, which is 40% higher than 1.0 V of traditional carbon electrodes. As such, supercapacitors can have higher energy density and power density with the RAC/MnO composite electrodes. The experimental equipment for synthesizing the electrodes is very simple and is promising for large-scale commercialization. [ABSTRACT FROM AUTHOR]

• NiS Sodium lignosulfonate. • Activated carbon Composite electrode materials. • Cycle life Asymmetric supercapacitor. In this paper, NiS nanoparticles had been successfully loaded on activated carbon (AC) derived from sodium lignosulfonate via hexadecyl trimethyl ammonium bromide assisted hydrothermal method. Due to synergistic effects of AC and NiS nanoparticles, the conductivity of the NiS/AC electrode is significantly improved, and the composite electrode exhibits a high specific capacity (677 C/g at 0.5 A g−1) and excellent rate performance. Moreover, an asymmetric supercapacitor (ASC) device was assembled with the NiS/AC composite as positive electrode and the AC as negative electrode to evaluate the electrochemical performance of NiS/AC composites in practical applications. The ASC device achieves a maximum energy density of 45.6 Wh/kg at a power density of 509.5 W/kg, and excellent cycling stability with 92.6% of capacitance retention after 20,000 cycles. The electrochemical performance suggests that NiS/AC composites have great application prospect as electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]