Sustainable Energy Systems: High Performance Lithium Ion Battery Components from Renewable Resources
Garcia-Negron, V., O. Rios, D. Keffer, and D. P. Harper.  2016.  Proceedings, 2nd Annual Women in STEM Research Symposium, Knoxville, TN, April 15, 2016. Poster.

Lignin is an abundant organic polymer found mostly in vascular plants that has potential applications due to its complex cross-linked interactions. Hardwood and softwood lignin exists in nature with several structure variants making it a versatile compound in the production of pulp, biomass, biofuels and carbon materials. The heterogeneous nature of lignin feedstocks makes elucidation of the relationship between processing and the resulting material structure difficult to predict. Investigation of the processing and the structure relationships in lignin-based materials can provide an understanding, which leads to optimized materials with targeted properties. In this work, we examined the role of unit operations in the carbonization process of lignin. Specifically, we varied the presence, temperature and duration of thermal stabilization, pyrolysis and passivation. We also examined the effect of ball milling techniques. The resulting materials were characterized at the atomic and micro-scales using x-ray diffraction, elemental analysis, and electron microscopy. High temperature carbonization produced a greater graphitization, which has been shown to correlate with charge capacities. Consequently, a properly designed carbonization process for lignin is well suited to generating low-cost, high-efficiency electrodes for next generation Lithium ion batteries. Characterization of the electrochemical behavior of coin cell batteries using lignin-based electrodes shows competitive performance compared to traditional graphite electrodes, at a fraction of the cost.