Production of Si-doped biomass-derived materials: effect of support type, activation and doping conditions

Abstract

Biomass-based carbonaceous materials have a great deal of promise for usage as anode material in lithium-ion batteries, which are one of the safest and most energy-dense energy storage technologies. The scientific community has assigned considerable focus on sustainable carbon production methods because of their low cost and eco-friendly features. Sustainable materials were produced as a result of selecting the renewable resource, and it also contributed to waste management since the feedstock was furniture industry waste. Herein, it was aimed to produce silicon-doped carbonaceous materials under different activation and doping conditions by using biomass and biochar support. Spruce wood sawdust, which had a carbon content of 46.55 wt.%, lignin content of 35.21 wt.%, and lower ash content (1.41 wt.%), was a suitable raw material to be evaluated by the pyrolysis method. Since the highest char yield was achieved in the pyrolysis reactions performed at 400 degrees C, silicon-doping experiments were executed with the biochar sample obtained at this temperature. Acidic and alkaline activations were applied to samples to specify the impacts of various activation conditions on the characteristics of the silicon-doped carbonaceous materials. In order to examine the effect of doping conditions on the crystalline structure, the reaction medium was changed to air and nitrogen. The produced silicon-doped carbon materials were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX) and EDX-mapping techniques. According to the characterization results, no crystalline silicon peaks were observed in the sample produced at 700 degrees C, 8 h. The porous structure of the biochar was preserved in each synthesis condition and silicon was homogeneously distributed in the carbon structure. The highest silicon content of 27.43% was obtained as a result of applying the heating process at 550 degrees C for 6 h after silicon loading to the biomass. The preparation of silicon-doped porous carbonaceous materials from spruce sawdust and char via thermochemical and chemical methods with appropriate properties reveals an important potential in terms of evaluating them in supercapacitors, which are among the developing electrochemical energy stores.