Polymer Electrolyte Through Enzyme Catalysis for High Performance Lithium-Ion Batteries

摘要

This project was initiated with the idea of using alternative means for the synthesis of polymer electrolytes with high yield, efficiency and ease of the processes used. Enzyme catalysis meets these criteria, and was used for this purpose by incorporating amorphous segments of poly (ethylene glycol), PEG, onto a monomer which can be easily polymerized via enzyme catalysis. The goal was to lock the PEG segments onto a polymer backbone such that chemical and electrochemical stability is achieved. To accomplish this task, we have substituted the basic monomer with PEG segments of various molecular weights. We have successfully polymerized such systems in aqueous media and characterized them. Characterization of the polymers synthesized in this effort yielded very encouraging results as far as ionic conductivity goes, approaching an unprecedented room-temperature value of 0.001 S/cm. The various characterization efforts have indicated that although the glass transition temperature (Tg )is low, the melt and decomposition temperatures are high enough for use of such materials in lithium ion batteries in a wide temperature range. The low Tg is due to the high mobility of the PEG component, and the good thermal stability is due to the carrier polymer obtained via enzyme catalysis. However, we went beyond this point and prepared a proprietary formulation, which takes advantage of the collective properties of the different components, and where the PEG segments become much longer through this process, without compromising their much-needed amorphous character. A fully solid state system with high fluidity of the PEG segments has resulted. We have also experimented with novel ionic gels based on our polymers without the incorporation of solvents as is usually the case in other efforts which employ propylene carbonate and the likes. Such materials are highly porous, with a strong ionic character, and would be developed further in the.