Improved lithium-ion battery electrolyte materials that minimize concentration polarization and facilitate high lithium-ion transport are desirable to enable devices with longer lifetimes and higher energy densities. In this work, we harnessed a self-doping strategy with a block polymer (BP) framework to simultaneously enhance the mechanical integrity and lithium ionic conductivity of the electrolyte material. Due to the incorporation of an anion tethered to the side chain of a monomer segment, anion motion was hindered, minimizing charge polarization across the electrolyte. The BP material consisted of two blocks: (1) a mechanically robust block and (2) a heteropolymer block composed of ion-conducting and self-doping monomer segments, in which the ratios between the two components determined the effective salt-doping ratio. BPs were synthesized by sequential atom transfer radical polymerization (ATRP) and activators regenerated by electron transfer (ARGET) ATRP, which enabled use of a relatively low concentration of copper catalyst for more facile removal of the catalyst post-polymerization. Lithium-ion conductivity was measured by alternating current impedance spectroscopy and direct current polarization methods and was related to the self-doping ratio of the electrolyte. The ion motion was impacted by the self-doping ratio of the electrolyte domain, and this behavior was correlated to the glass transition temperatures and morphology of the BP. Overall, this effort elucidated important design parameters necessary to enhance self-doped lithium-ion battery electrolyte materials.

Self-doped ion-conducting block polymers for lithium-ion battery electrolytes

256th National Meeting (2018)

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