CAREER: Modeling Polymer Electrolyte Microstructure: How Polymer Architecture Controls Ion Conduction

Ohio State University, The, Columbus OH

Investigators

Abstract

NON-TECHNICAL SUMMARY This CAREER award supports theoretical and computational studies of polymeric materials for potential applications as non-flammable polymer electrolytes in a new generation of safe, lightweight batteries. The goal of this project is to develop and use innovative computational and theoretical tools to model ionic conductance in block copolymer based materials. In diblock copolymers, chains of the two different chemical types are connected together, forming a long chain molecule with different chemical composition on each end. If the two blocks are different, they phase separate (like oil and water) forming nanometer scale structures. Of special interest for future applications are diblock copolymers with added salts in which one block forms soft and the other forms hard domains. The softer domains conduct lithium ions (serving the purpose of the battery electrolyte), while the harder domains prevent the growth of lithium dendrites which can short-circuit the battery. The PI's group will focus on understanding how polymer structure controls final materials properties. The education and outreach part of this project builds on development of an interactive simulation setup with a 3D display and force-feedback joystick to communicate to students across the age groups and to the general public what polymers are and how their structure impacts material properties. The PI and members of her group will participate in the "Translating Engineering Research to K-8" (TEK8) program through the College of Engineering at OSU and use the existing infrastructure of Ohio State's STEAM Factory and Women in Engineering program to increase interest of underrepresented groups in science and engineering. TECHNICAL SUMMARY This CAREER award supports research and educational activities with a focus on development of innovative computational tools for modeling ionic conductance in block copolymer based materials. The goal is to use theoretical techniques and computer modeling to elucidate the underlying physics behind the structure and conductance of polymeric materials and to guide future synthesis efforts. The experimental systems that inspire this research are nonflammable battery electrolytes that are inherently safer and could increase battery energy density while preventing lithium dendrite growth. The approach is designed to overcome difficulties associated with the multiple time and length scales of the problem due to complex polymer morphology, effects of packing of finite size ions and polymeric units, and the long-range electrostatic interactions between charged species. The theoretical approach will be based on the fluid density functional theory and simulation techniques will include molecular dynamics simulations of the coarse-grained models. To bridge multiple time and length scales the strategy will be to obtain the equilibrium polymer morphology from density functional calculations and to use this structure as a starting point for coarse-grained simulations. This approach will be applied to model material properties of diblock copolymers and tapered copolymers, in which a region with a gradient in monomer composition is added between two pure blocks. The goal of this approach is to efficiently sample parameter space and to show how the materials properties depend on polymer architecture, polymer morphology, and ion concentration. The education and outreach part of this project builds on development of an interactive simulation setup with a 3D display and force-feedback joystick to communicate to students across the age groups and to the general public what polymers are and how their structure impacts material properties. The PI and members of her group will participate in the "Translating Engineering Research to K-8" (TEK8) program through the College of Engineering at OSU and use the existing infrastructure of Ohio State's STEAM Factory and Women in Engineering program to increase interest of underrepresented groups in science and engineering.