MODULATING ION AGGREGATION AND MOBILITY IN IONOMERS

Open Access
Author:
Zydonik, Zachary Lee
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Janna Kay Maranas, Thesis Supervisor
  • Michael John Janik, Honors Advisor
Keywords:
  • Solid Polymer Electorlytes
  • Sodium Ion
  • Sulfonation
  • PEO
  • batteries
  • ion content
  • mechanical properties
  • percolation
  • ion transport
  • transport mechanism
  • ionomers
Abstract:
Rechargeable metal-ion batteries including Lithium-ion and Sodium-ion batteries represent the most promising candidates for achieving the high energy density demands of electrochemical storage. The development of energy-dense storage capabilities is of current focus in the scientific community due to its potential to revolutionize renewable energy sources, such as the electric car, making these resources more accessible. One of the significant downfalls of this technology, however, are the organic liquid electrolytes used to facilitate ion transport. While these solvents result in high ion conductivities, they suffer from high production costs as a result of their volatile and flammable character. Replacement of the organic solvents with an alternative electrolyte may offer a solution. Solid polymer electrolytes (SPEs) are ionomers, or polymers containing charged ions. Using SPEs in batteries reduces total weight and increases energy density; these batteries also benefit from safer handling due to the polymer’s inert characteristics. However, low ion conductivity, on the order of 10-7 to 10-4 S/cm, compared to liquid electrolytes at 10-2 S/cm represents a significant drawback. A common polymer used in SPEs is Poly-(ethylene oxide) (PEO) due to its low toxicity, and high electrochemical stability. Employing PEO as part of the polymer backbone has the consequence of immobilizing the anionic ether oxygen atoms, leaving the cation as the only mobile species. The mechanism behind the transport of the cation in these single-ion conductors is of interest. The proposed work aims to decouple ion transport from the segmental motion of the polymer by exploring ion transport in PEO-based sulfonate single ion conductors. This will be evaluated in terms of sulfonation, varying ion content and mechanical properties. The objective of this thesis is to assemble previous simulation work and prepare three papers for publication.