Lignin-rich carbon products are becoming a promising material for commercial use as availability increases and cost remains low. The relationship between feedstock, processing conditions and nanostructure of the nanocomposite product as a result of carbonization (pyrolysis and reduction) is not well-established. Thus, further performance improvements can be achieved with process and feedstock optimization. In this study, lignin feedstocks obtained from softwoods, hardwoods, and grasses were carbonized at temperatures of 1050 and 2000 °C. Transmission electron microscopy was conducted at 200 kV in a diffracted pattern mode revealing comparable levels of graphitization between lignin carbon and commercial graphite under certain processing conditions. Diffracted patterns indicate that a higher volume fraction of the graphitic domain is present in the reduced temperature of 1050 °C in kraft softwood when compared to hardwood yellow poplar. In both feedstocks, the size of the crystalline domains increases with increasing processing temperature. The bonding and ratios of sp<sup>2 </sup>and sp<sup>3</sup>are resolved by using electron energy loss spectroscopy in the range of 250 to 350 eV in order to identify the ionization edges generated by the number of inelastic scattered electrons. Ongoing experiments will provide a complete understanding of carbon bond interactions to leverage processing-structure-performance relationships for energy storage applications.

Structural characterization of carbonized lignin feedstocks via transmission electron microscopy

2019 Spring National Meeting

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