In this presentation, we demonstrate synthesis of a new polymer, lignin-graft-poly(ethylene glycol) (lignin-graft-PEG) and its ionic conductivity characterizations for a potential application as a solid battery electrolyte. Lignin is an important aromatic-rich biomass polymer that is cheap, abundant, and sustainable. However, the application of lignin-based polymers in the solid electrolyte field is rare due to challenges related to performing well-defined polymer synthesis on lignin in order to impart sufficient electrochemical properties for battery applications. The new lignin-based polymer for a solid battery electrolyte application is prepared by two main synthetic steps. First, hydroxyl groups of natural lignin were chemically modified to possess alkene groups via esterification (lignin-alkene). Then, separately prepared thiol-terminal PEG is covalently grafted onto the lignin-alkene by ruthenium complex-catalyzed photoredox thiol-ene reaction. The photoredox thiol-ene reaction is activated by visible blue light that is moderate reaction condition, readily available, cost-effective, and environmentally friendly. Moreover, versatile reaction control is possible in the developed photoredox thiol-ene reaction due to the temporal and spatial control offered by visible light irradiation. By using the photoredox thio-ene reaction, two different lignin-graft-PEGs were prepared having 21 wt% lignin (lignin-graft-PEG 550) and 32 wt% lignin (lignin-graft-PEG 2000). Polymer graft electrolytes were prepared via addition of lithium bis-trifluoromethanesulfonimide (LiTFSI). The polymer graft electrolytes exhibited high ionic conductivity with only moderately impacts on conductivity at elevated temperature compared to homopolymer PEG. In addition, the high contents of lignin in lignin-graft-PEG provides strong mechanical properties that is essential property for solid polymer electrolytes. Overall, these revealed features show a lignin-graft-PEG is a promising new material for solid polymer electrolytes in battery applications.

Novel synthesis approaches for lignin-based polymeric battery materials

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.