Interfacial-modified block polymers for lithium battery electrolytes
Date
2015
Authors
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Publisher
University of Delaware
Abstract
Block polymer (BP) electrolytes have become increasingly attractive for lithium-based battery applications due to their low volatility, sufficient mechanical strength, and thermal and electrochemical stability in comparison to conventional liquid electrolytes. However, current BP electrolytes suffer from poor conductivity near room temperatures (due to polymer crystallization) and high processing costs (due to unfavorable polymer-polymer interactions). To overcome the above limitations, this dissertation proposes a design of new BP electrolytes with a specific focus on network nanostructures using tapered block polymers (TBPs). The work presented in this dissertation examined the morphological, thermal, and electrical properties of TBPs. Incorporating a taper interface in BPs was found to reduce the unfavorable polymer-polymer interactions and stabilize additional morphologies in salt-doped BPs. Most significantly, a double gyroid network window was located in the salt-doped normal-tapered system. Additionally, the tapered interfaces demonstrated a unique handle for manipulating the glass transition temperature (Tg) of BP electrolytes through adjustments in the taper profile and taper volume fraction, thus enabling control over the ionic conductivity. Finally, a novel synthetic strategy for generating dual-tapered triblock terpolymers was presented. An alternating gyroid-forming tapered triblock terpolymer was generated, showing the ability to retain network structures in dual-tapered BP systems. Overall, the approaches presented in this dissertation provide the opportunity to design cost-effective, highly-efficient, and stable energy storage devices.