Charged polymers form the basis of solid materials that can be used to conduct lithium ions in a battery electrolyte, or used to purify salt water or other liquids. Normally, charged polymers are very flexible and do not have strong mechanical properties. This project involves a solid material formed from a mixture of a very rigid and strong charged polymer (similar to Kevlar(R)) and an ionic liquid (also known as a molten salt). This new material, which is called a molecular ionic composite (MIC), combines the best properties of solids and liquids. MIC materials are stiff and non-flammable solids and yet they can conduct ions like lithium and sodium with very low resistance, as if the ions were in a liquid. The properties of MICs can also be widely tailored for potential use in different applications such as water purifiers, electromechanical sensors, or artificial muscles. This project will combine cutting edge research tools such as nuclear magnetic resonance (NMR) and X-ray analyses, materials science theories, and computational molecular simulations in order to build fundamental understanding of how MIC materials work. By combining such interdisciplinary knowledge and insights, these researchers will work to create new designs for MIC materials for devices such as safer, cheaper, and more lightweight lithium batteries. This project shows promise for feeding into advanced battery materials technology, thus enabling a potential new avenue for US business impact on the $20B global battery market. Students and collaborators involved in this project will gain new knowledge about these novel polymeric conductors, and this new knowledge will be integrated into polymer science classes on the Virginia Tech campus and propagated to K-12 children and their parents in an educational outreach program based in Southwest Virginia.
This project aims at a non-flammable solid with the modulus of poly(methyl methacrylate), but where a high density of ions inside move as if they were in a liquid. It builds on the discovery of a new class of polymeric ion conductors that are termed molecular ionic composites (MICs). The prototypical MICs, formed from a rigid-rod anion-containing polymer and an ionic liquid (IL), exhibit the following special combination of tunable properties: ionic conductivity up to 8 mS/cm, widely tunable elastic modulus (0.01−3 GPa), and thermal stability up to 300 degrees C. MICs show promise for allowing use of metal electrodes in lithium and sodium batteries, potentially enabling higher energy density as well as battery operation over a wide temperature range and with inherent fire resistance. While these materials display impressive properties, researchers are only beginning to understand the origins of why such fast ion transport is commensurate with such a stiff and robust material matrix. This project combines fundamental polymer analyses involving nuclear magnetic resonance (NMR), X-ray scattering, and microscopy with molecular dynamics simulations and theories of conduction and oriented matter. Better understanding of the fundamental nature of MICs could feed into design of new compositions to meet desired requirements for battery electrolytes or other molecular separations applications. Students and collaborators involved in this project will gain new knowledge about these novel polymeric conductors, and this new knowledge will be integrated into polymer science classes on the Virginia Tech campus and propagated to K-12 children and their parents in an educational outreach program based in Southwest Virginia.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
