Magnesium-sulfur (Mg-S) rechargeable batteries are a potentially cost-effective and high energy density solution for use in electric transportation. One technical barrier to this technology is that the electrolyte requirements for rechargeable Mg metal batteries have thus far limited cycle life when used with sulfur cathodes. In this project, the PI will conduct fundamental research on UV light-curable polymeric barrier films for the electrolyte-cathode interface to enable capacity retention of the battery. The functional polymeric films will prevent cross-over of certain reactive species, thus mitigating deleterious reactions and maintaining chemical integrity of the anode, electrolyte, and cathode of the battery. The fundamental scientific knowledge generated by this work could enable advances in new materials for other applications where performance characteristics are influenced by ion transport and ion rejection. Additionally, the number, diversity, and training of the next generation of researchers in the chemical sciences and engineering will be enhanced by the further development of an outreach module for high schools and by the broadening participation of women and underrepresented minority undergraduate and graduate students in research.
This project addresses two fundamental limitations in Mg-S battery development: breakdown of active cathode material by reaction with electrolyte species and passivation of the anode by cathode intermediates. Both issues may be mitigated by preventing the transport of undesirable species across the electrolyte-cathode interface. Structure-property relationships of polymeric barrier films to enable Mg-S battery cycling will be interrogated. In the first theme of the project, self-supporting films will be created by crosslinking of a highly dissociable magnesium-titrated ionic monomer with a variety of difunctional oligomeric monomers of varying chemistry and length. Ex-situ studies will evaluate the efficacy of the films in conducting magnesium cations and excluding anionic polysulfides and/or nucleophilic complexes. The mechanisms of steric, dielectric, and electrostatic exclusion will be independently probed. In the second theme, the UV-curable barrier films will be blade coated directly onto sulfur cathode sheets. Effects of thickness, conformity, and chemistry of the films on full cell Mg-S battery performance will be investigated. The performance of the cells will be linked with the fundamental characteristics of the films.
