Lignin-Based Solid Polymer Electrolytes: Lignin-Graft-Poly(ethylene glycol).

Area of Science:

• Materials Science
• Polymer Chemistry
• Electrochemistry

Background:

• Lignin, an abundant and sustainable aromatic polymer, is underutilized in solid electrolytes due to synthesis challenges.
• Developing novel polymer electrolytes is crucial for advancing energy storage technologies.

Purpose of the Study:

• To synthesize and characterize lignin-graft-poly(ethylene glycol) (PEG) for solid electrolyte applications.
• To evaluate the ionic conductivity of these novel lignin-based polymer electrolytes.

Main Methods:

• Functionalization of natural lignin's hydroxyl groups to alkenes.
• Graft-copolymerization of PEG thiol onto lignin via photoredox thiol-ene reaction.
• Preparation and conductivity testing of polymer electrolytes with lithium bis-trifluoromethanesulfonimide.

Main Results:

• Two lignin-graft-PEG copolymers with varying lignin content (22 wt% and 34 wt%) were successfully synthesized.
• The polymer graft electrolytes achieved ionic conductivity up to 1.4 × 10^-4 S cm^-1 at 35 °C.
• Lignin incorporation resulted in significantly higher ionic conductivity at ambient temperature compared to pure PEG.

Conclusions:

• Lignin-graft-PEG is a promising material for solid polymer electrolytes.
• The developed materials offer enhanced ionic conductivity, particularly at room temperature.
• This work demonstrates a viable route for incorporating sustainable lignin into advanced energy storage materials.