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Phase behavior and Li + Ion conductivity of styrene‐ethylene oxide multiblock copolymer electrolytes
Author(s) -
Sarapas Joel M.,
Saijo Kenji,
Zhao Yue,
Takenaka Mikihito,
Tew Gregory N.
Publication year - 2016
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.3753
Subject(s) - materials science , copolymer , polystyrene , polymer chemistry , volume fraction , lithium (medication) , electrolyte , analytical chemistry (journal) , chemical engineering , conductivity , styrene , polymer , chemistry , composite material , organic chemistry , medicine , endocrinology , electrode , engineering
Solid polymer electrolytes are attractive materials for use as battery separators. Here, a molecular weight series of polystyrene–polyethylene oxide (PEO) multiblock copolymers was synthesized by the thiol–norbornene click reaction. The subsequent materials were characterized both neat and with a lithium bis ‐(trifluoromethane)sulfonimide salt loading [(Li)/(EO)] of 0.1. In general, neat samples demonstrated crystallinity scaling with PEO content. Lithium ion‐containing samples had broad scattering peaks, half of which displayed disordered scattering, even at the lowest block molecular weights (polystyrene = 1 kg/mol, PEO = 1 kg/mol). Fitting of disordered scattering data, using the random phase approximation, yielded χ RPA and R g values that were compared with recent predictive work by Balsara and coworkers. The predictions were accurate near the volume fraction f PEO = 0.5 but deviated symmetrically with volume fraction asymmetry. Samples were also analyzed by electrochemical impedance spectroscopy for their potential to conduct lithium ions. Samples with f PEO ≥ 0.5 demonstrated robust conductivity, whereas samples below this volume fraction conducted very poorly, with one exception ( f PEO = 0.24). This work expanded upon our recently reported approach to multiblock copolymer synthesis, demonstrating the improved access of materials to further our fundamental understanding of multiblock copolymers. Copyright © 2016 John Wiley & Sons, Ltd.