Solid polymer electrolytes are of growing importance as flexible, nonflammable alternatives to liquid battery electrolytes. Many synthetic options, including polymer architecture, copolymer composition profile, and polymer and anion chemical type, provide a vast design space to tailor these materials for use in specific applications. Here, we apply bead-spring polymer models of salt-doped and single-ion polymer electrolytes, with a small number of parameters adjusted based on the chemical system of interest, to provide insight into which factors are crucial drivers of observed behavior and possible guidelines for design of new materials. We build on prior work on linear polymer chains of uncharged polymer beads with charged spherical ions (including long-range Coulomb interactions), which also includes ion-monomer interactions to account for ion solvation based on polymer dielectric constant. We now include a more specific mapping to polymer and ion chemistry—we adjust bead size, angle potential, and interaction strength, while keeping the same forms of the interactions. We create polystyrene-
block-poly(
oligo-oxyethylene methyl ether methacrylate) (PS-b-POEM) by setting backbone parameters based on polymethyl methacrylate homopolymer properties and side chains based on polyethylene oxide homopolymer properties. Angles between adjacent bonds, bead sizes, and like-like polymer interactions are set to match the homopolymer Kuhn length density and glass transition temperatures. We add salt with appropriate relative bead sizes and calculate ion conductivity as a function of side chain length. This model reproduces the Vogel-Fulcher-Tammann form of conductivity versus temperature and similar increasing conductivity with side chain length as seen experimentally. We then expand the model to consider related single ion conducting materials and blends, focusing on how polymer polarity and ion size impact ion solvation and dynamics.
This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC0014209.
