Blocky woodceramics/nano-MnO2 prepared by one-step hydrothermal activation as supercapacitor electrode

Abstract In order to fully apply biomass materials to the field of energy storage, blocky woodceramics electrode with three-dimensional network structure is prepared from discard pine, hydrothermal activation and MnO2 deposition are employed to improve the performance. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observation are carried out, which indicate that different forms of MnO2 grow uniformly on the surface and internal pores of woodceramics. The high-magnification TEM image shows that the narrow-striped lattice of entangled MnO2 can be clearly observed. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis results exhibit that the as-obtained MnO2 by the one-step hydrothermal activation method mainly exists in the form of Mn4+, as well as a small amount of Mn3O4 and Mn2O3. In addition, electrochemical tests present that the addition of transition metal element Mn introduces pseudocapacitance, which is beneficial to the improvement of the electrode materials electrochemical performance. The specific capacitance of containing Mn electrode material can reach 293.7 F g−1 under the current density 0.1 A g−1, which is 3.5 times that of the sample without MnO2. Moreover, the retention rate of specific capacitance can maintain at 81.9% after 5000 cycles of charge and discharge. The energy density and power density are 18.6 Wh kg−1 and 1249.8 W kg−1, respectively, which has an excellent performance.