1. Center for Functional Nanomaterials Seminar

    "Microstructure evolution in block copolymer copolymer/lithium salt electrolytes"

    Presented by Xin (Matt) Wang, New York University

    Monday, March 16, 2015, 10 am
    CFN - Bldg. 735 Second Floor Conference Room B

    Hosted by: Charles Black

    Mixtures of salts and nanostructured block copolymers are promising solid electrolytes for rechargeable batteries with lithium metal anodes. For my doctoral research, I studied the evolution of microstructure in block copolymer/lithium salt mixtures on both nano- and micro- scales under various thermal conditions. My talk concerns the block copolymer/lithium salt mixture, polystyrene-b-polyethylene/lithium bis (trifluoromethane sulphone) imide (SEO/LiTFSI for short), primarily studied through depolarized light scattering (DPLS), to obtain the microstructural information about SEO/LiTFSI mixtures with different concentrations and molecular weights at different temperatures. The results indicated the addition of salt strongly affects the thermodynamics and kinetics of the microstructure of the mixture. We confirmed the presence of a coexistence temperature window for low molecular weight block copolymer/salt mixtures predicted by theory (the coexistence of ordered and disordered phases in equilibrium). For high molecular weight mixtures, a hypothesis has been proposed to explain the discrepancy between the results of SAXS and DPLS on identical mixtures. A high defect density increased the conductivity of block copolymer electrolytes.