Plant Cell Wall Inspired Functional Ion Conducting Nanomaterials for Energy Applications

Current initiatives to minimize the global carbon footprints demand the best utilization of renewable energy resources and development of environment friendly next generation materials for energy conversion and storage. The proposed work takes inspiration from plant cell walls and utilizes the major polymer lignin present in plant cell walls to design highly functional ion conducting materials. Lignin imparts mechanical strength to plant cell walls. Lignin exhibits Young’s modulus 25 times higher than the most popular ion conducting polymer, Nafion used for proton exchange membrane fuel cells. Moreover, lignin is heavily functionalized with hydrophilic hydroxyl (-OH) groups which facilitate ion channel formation for efficient proton conduction. The high glass transition temperature and segmental motion in the presence of little or no moisture make lignin ideal for high temperature and low humidity ion conduction where current ionomers lag behind. Our recent work shows that sulfonated lignin (by-product of paper industries) can offer great material strength and ion conductivity in micro to nanoscale thick materials, yielding cheaper, efficient ion conducting ionomers for many energy conversion and storage devices.