High Performance Polymer Electrolytes through High Dielectric Polymers and Blends

University Of Texas At Austin, Austin TX

Investigators

Abstract

High capacity batteries are key to increasing the range and performance of sustainable transportation technologies. The use of polymer electrolytes is a promising strategy to increase the capacity and safety of lithium batteries. This combined theoretical and experimental project will fill the gaps in fundamental understanding of ion conduction in pure polymers and their blends to improve performance for real-world applications. A polymer blending strategy enables the combination of favorable characteristics at blend compositions that maximize electrolyte performance. The combined use of theory and experiment in this project increases the efficiency of discovery, the depth of fundamental understanding, and speeds progress on this economically and environmentally important field of research in energy storage. The results of the proposed fundamental research will be directly applicable to development of more efficiently conducting polymer electrolytes for deployment in lithium batteries. Such advances can potentially impact applications as diverse as cellphone batteries, development of electric cars, and large scale grid storage. To complement the research efforts, the PIs will carry out educational and outreach activities. These will include graduate and undergraduate student research initiatives aimed at synergistic theoretical-experimental activities, the development of a new educational module on polymer electrolytes and sustainable energy resources, and outreach efforts on sustainable energy and batteries that are directed towards K-12 audiences. Given the advantages of polymer electrolytes in the context of lithium batteries, the continuing challenge for macromolecular electrolytes has been to increase ionic conductivity. The project will present new concepts which motivate the design of new materials that would both advance fundamental understanding of polymer electrolytes and enable appreciable improvements in storage capacity. The overall hypothesis of the research program is predicated on the observation that ionic conductivity in a homologous series of polyethers was shown to depend primarily on the dielectric constant and not glass-transition temperature or viscosity of the parent polymer. Significantly, this suggested the hypothesis that there could be parametric regimes or classes of polymeric materials in which the transport of ions is only limited by the solubility and dissociation of the ions themselves, and that further increases in ionic conductivity would be possible by enhancing the inherent dielectric constant of the material. Ultimately, increases in dielectric constant may be accompanied by an increase in the glass-transition temperature and that the resulting slow segmental dynamics of the polymer will hinder ion conduction. The project includes study of blends of high-dielectric polymeric materials with low-viscosity analogs to achieve further enhancement in ion conductivities not limited by polymer segmental dynamics. The ultimate result of the integrated study on ion transport in polymer materials will identify the importance of the polymer dielectric constant upon ion conductivities, and provide a new quantitative understanding of ion transport as a function of polymer properties. Furthermore, the research will exploit the non-ideal conductivity characteristics of blends that will lead to a new understanding of the conductivity characteristics of polymer mixtures and may unite the understanding of ion transport in polymer electrolytes with those of small molecule electrolytes.