Construction of fungus waste-derived porous carbon as electrode materials for electrochemical supercapacitor

Biomass-derived carbons were regarded as one of the most promising electrode materials for supercapacitor. Among which, fungus waste-derived carbon materials with high specific surface were considered as better electrode materials. In order to further understand the electrochemical properties of different fungus-derived carbon materials as electrode for supercapacitor, carbons derived from three kinds of fungus waste (Flammulina velutipes, Pleurotus ostreatus and Shiitake mushroom stipe) were prepared and their electrochemical performances were studied in this research. X-ray diffraction, N2 adsorption–desorption, scanning electron microscopy, transmission electron microscope, Fourier transform infrared spectroscopy, etc. were used to characterize the physicochemical properties. The electrochemical performances of the prepared electrode materials were tested based on an electrochemical workstation at ambient temperature in three- and two-electrode systems with 1 M Na2SO4 solution. It was found that the supercapacitor with F. velutipes stipe-derived biochar (FVB) electrode had higher specific capacitance (197 F/g at 0.5 A/g) than supercapacitor using other fugus-derived biochar as electrode. The Nyquist plots of FVB were almost vertical with the vertical axis at low frequencies. The equivalent series resistance (Rs) of the FVB (2.5 Ω) was lower than other supercapacitors using fungus-derived carbon materials as electrode. The charge transfer resistance (Rct) of FVB-based symmetric supercapacitors was lower than that of the other two supercapacitors. After the continuous charge/discharge test for 10,000 cycles, the charge/discharge curve of supercapacitor was still smooth, and the FVB-based supercapacitor still remained about 98.7% of its initial value.