New materials will be synthesized with the goal of improving the function and safety of solid polymer electrolyte supports in lithium ion batteries. Polymers based on two types of dicarboximide oxanorbornyl monomers will be synthesized using ring opening metathesis techniques creating a fairly rigid and bulky backbone. This backbone may assist in more effectively decoupling ionic motion from polymer segmental motion. Polymers with varying lengths of ethylene oxide side chains and molecular weights will be investigated to maximize lithium ion conductivity. Accordingly, the optimized monomers will be incorporated into diblock and random copolymers with a second monomer that has a substantially higher glass transition temperature. The random copolymers will be evaluated at compositions where the ionic conductivity is balanced with increased modulus due to the higher glass transition monomer. The phase diagram of a diblock copolymer system with one block using the optimal ethylene oxide side chain and the other block having a high glass transition will be studied to understand how the microphase separated morphology (e.g., lamellae or cylinder) might benefit ionic conductivity. Characterization of the polymer structure and dynamics will include dielectric spectroscopy, X-ray and neutron scattering, atomic force microscopy, and possibly solid-state NMR. This research also includes a shared component where some of the characterization will be conducted on NSF funded equipment and with collaborators at other universities, and at national user facility laboratories. Undergraduate student researchers will carry out this research over the course of three years.
NON-TECHNICAL SUMMARY:
This research project will create and study strategically tailored materials for use as membranes in lithium ion batteries. These new membranes may lead to improved safety and performance in lithium ion batteries, benefiting the growing necessity for better and safer energy storage systems. These new materials might allow lithium batteries to be lighter, smaller, and constructed out of materials that are much less flammable than conventional materials. This research will include a number of broader impacts. Our future scientific work force will be benefited by direct involvement and education of undergraduate students in all aspects of this research. Collaborations will be established with scientists at other local and national universities, and federally supported national user facilities will be utilized in these studies such as Oak Ridge National Laboratory. Also, increased exposure of underrepresented high school students to science will take place through outreach activities involving the Mathematics, Engineering, and Science Achievement (MESA) program. These activities will include mentoring by undergraduate research students in polymer science experiential learning activities, chemical demonstrations, and demonstrations of modern scientific instrumentation.
