Polymer Polarity as a Design Parameter for Polymer Electrolytes

Download or read book Polymer Polarity as a Design Parameter for Polymer Electrolytes written by Bill Kristoff Alban Wheatle (Jr.) and published by . This book was released on 2020 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Motivated by the need to improve the safety and energy density of lithium-ion batteries, we explore polymer polarity as a design parameter for polymer electrolytes using molecular simulation. We first correlate molecular-level static ionic aggregation with the degree of uncorrelated ionic motion modulated by the host polymer polarity as a potential means to improve ionic transport. Next, we explore the extent to which polymer polarity can be used as a design parameter alone, finding that a competition between ionic aggregation and polymer dynamics limits ionic conduction. We subsequently investigate how polymer polarity influences the correlations between ionic transport and other design parameters, such as host molecular weight and salt concentration. We discover that such correlations exist only above a threshold polymer polarity where ionic aggregation is largely insensitive to these design parameters. We turn to the success of small molecule electrolytes, whose fast ionic transport is mediated by hosts that typically are blends of high mobility and high polarity components. We find that ionic transport can similarly be enhanced when miscible polymer blends with sufficient contrast in polarity serve as the electrolyte host. Finally, we design blend polymer electrolytes whose performance metrics are their mechanical strength and rate of ionic transport using the machine learning technique known as Bayesian optimization. This algorithm identifies a trade off between these performance metrics and identifies the evolution of design parameters, such as host polymer polarities and molecular weights, with increasing emphasis on ionic transport