Fabrication and Surface Modification of Flat Lignocellulosic Carbon Materials

Abstract

Flat lignocellulosic carbon materials (FLCMs) with a honeycomb structure were successfully fabricated by carbonizing the softwood Picea jezoensis (Ezomatsu, Japanese conifer) and the hardwood Cercidiphyllum japonicum (Katsura). Scanning electron microscopy images of the FLCMs showed distinct differences in the tracheid diameter distributions between the FLCMs made from the softwood and hardwood. High-temperature heating decreased the electrical resistivity of the FLCMs. Vacuum ultraviolet irradiation in an oxygen atmosphere (VUV/O3) helped in increasing the surface hydrophilicity and specific surface area of the materials while maintaining their low electrical resistivity. The surface-treated FLCMs were successfully used to fabricate self-supporting electrodes for electric double-layer capacitors (EDLCs).

Film of lignocellulosic carbon material for self-supporting electrodes in electric double-layer capacitors

“…9,10 Although many carbon materials made of lignocellulosic resources have been reported, there are very few reports of self-supporting carbon materials suitable for EDLC electrodes. 11,12 Even in these reports, the conventional materials used were several millimeters thick, which lengthened the distance between electrodes and was disadvantageous in terms of EDLC performance.…”

“…The carbonization process was similar to those we have reported previously. 12,15 Before the first step of the carbonizing process, FLCMs were set into a fixture made of heat-resistant glass to prevent warps and cracks, and were then placed in an electric furnace (Sakamoto Co., Ltd., Japan). The samples were then carbonized at 300 • C for 6 h, before being allowed to cool naturally at room temperature.…”