Rational Design of Nanostructured Polymer Electrolytes and Solid-Liquid Interphases for Lithium Batteries

This thesis makes significant advances in the design of electrolytes and interfacesin electrochemical cells that utilize reactive metals as anodes. Such cells are of contemporary interestbecause they offer substantially higher charge storage capacity than state-of-the-art lithium-ion batterytechnology. Batteries based on metallic anodes are currently considered impractical and unsafe because recharge of the anode causes physical and chemical instabilities that produce dendritic deposition of themetal leading to catastrophic failure via thermal runaway. This thesis utilizes acombination of chemical synthesis, physical & electrochemical analysis, and materials theory toinvestigate structure, ion transport properties, and electrochemical behaviors of hybrid electrolytes andinterfacial phases designed to prevent such instabilities. In particular, it demonstrates that relatively low-modulus electrolytes composed of cross-linked networks of polymer-grafted nanoparticles stabilizeelectrodeposition of reactive metals by multiple processes, including screening electrode electrolyteinteractions at electrochemical interfaces and by regulating ion transport in tortuous nanopores. Thisdiscovery is significant because it overturns a longstanding perception in the field of nanoparticle-polymer hybrid electrolytes that only solidelectrolytes with mechanical modulus higher than that of the metal electrode are able to stabilizeelectrodeposition of reactive metals.