Battery electrolytes comprised of lithium salt-doped block polymers combine good mechanical integrity with high ionic conductivities, both of which are important for the design of solvent-free lithium batteries. While previous studies have focused almost exclusively on narrow dispersity diblock polymers prepared under stringent reaction conditions, very few studies have explored how increased dispersity in the conductive domain affects the morphology and Li-ion conductivity behavior. We will describe the synthesis of poly(styrene-block-ethylene oxide-block-styrene) triblock polymers with broad–dispersity O blocks (bSOS), by condensation polymerization followed by atom transfer radical polymerization (ATRP). After blending these bSOS samples with the salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at [Li+]:[O] = 0.09, small-angle X-ray scattering (SAXS) analyses reveal the formation of ordered lamellar phases with good long-range order when fO = 0.55–0.75. AC impedance spectroscopy measurements indicate that these materials also exhibit high ionic conductivities. These ionic conductivities are compared to those of narrow dispersity SOS triblocks doped with similar amounts of LiTFSI, as well as LiTFSI-doped narrow dispersity SO diblocks. On this basis, we derive new insights into the design of high performance polymer electrolytes for advanced Li-ion battery technologies.

Lithium-ion conduction through salt-doped, high dispersity poly(styrene-block-ethylene oxide-block-styrene) lamellae

2019 Fall National Meeting

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