Designing Ion-containing polymers for facile ion transport

Open Access
Author:
Liu, Wenjuan
Graduate Program:
Materials Science and Engineering
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
March 11, 2010
Committee Members:
  • Ralph H Colby, Dissertation Advisor
  • Michael John Janik, Committee Member
  • James Patrick Runt, Committee Member
  • Michael Anthony Hickner, Committee Member
Keywords:
  • Lithium ion batteries
  • ab initio calculations
  • ionic conductors
  • polymeric materials
  • dielectric spectroscopy
  • electrode polariz
Abstract:
The development of polymer electrolytes with sufficient ionic conductivity will enable the design of flexible, efficient Li ion batteries and is also of primary interest for actuators, alternative battery membranes, and within the membrane-electrode assembly of fuel cells. Optimization of ionic polymer (ionomer) compositions will provide single-ion conductors with the required conductivity for energy conversion applications, and further, that the identification of optimal compositions can be facilitated. Ab initio methods use the first principles of quantum mechanics to determine the electronic state of a system, and can therefore quantify interaction energies between species without parameterization from experimental studies. A bottom-up design strategy based on ab initio calculations can be rapidly applied to a wide variety of anions and cations in different polar media, enabling a detailed understanding of ion interactions and solvation by polar groups, in the aim of suggesting anion, polar side group, backbone combinations worthy of synthesis. Collaboration with on-going experimental efforts on ionomer synthesis and dielectric spectroscopy that measures populations of conducting ions and ion pairs, will allow for realization of ionomer compositions suggested by theory, as well as serve to validate models.