Solid polymer electrolytes in a poly(butadiene-acrylonitrile)–LiBr system

• Published in: Ionics Vol. 23; no. 12; pp. 3347 - 3363
• Main Authors: Yaroslavtseva, T. V., Reznitskikh, O. G., Sherstobitova, E. A., Erkabaev, A. M., Brezhestovsky, M. S., Bushkova, O. V.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2017; Springer Nature B.V
• Subjects: Butadiene; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrochemistry; Electrolytes; Energy Storage; Glass transition temperature; Ion currents; Ion transport; Ions; Lithium; Molecular interactions; Molten salt electrolytes; Nitriles; Optical and Electronic Materials; Optical microscopy; Original Paper; Phase composition; Polymers; Renewable and Green Energy; Solid electrolytes; Solubility; XRD; Polymer electrolytes; Li; Ionic conductivities; FTIR; conductors
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-017-2149-z

Poly(nitriles) are among the polymer matrices providing high salt solubility and, in some cases, superionic lithium conductivity at ambient temperatures observed in highly concentrated solvent-free polymer electrolytes. However, the properties of these electrolytes in which ionic aggregation prevails remain difficult to reproduce and predict, as current theories do not adequately model their attributes. The development of new concepts for ion transport in highly concentrated solid polymer electrolytes (SPEs) requires a better understanding of the fundamentals of structure formation in a polymer–salt system over a wide concentration range including salt precipitation. In an attempt to approach this goal, a series of fundamental studies was carried out on the systems based on a rubbery random copolymer of butadiene and acrylonitrile (abbreviated as PBAN). In the present work, LiBr with monatomic halide anion was used as a lithium salt. The effect of LiBr concentration (0.05 to 3.35 mol kg −1 ) on phase composition, ion–molecular interactions, glass transition temperature, and ionic conductivity was studied by optical microscopy, FTIR, X-ray diffraction, DSC, and impedance measurements. The results were compared with those of PBAN–LiClO 4 and PBAN–LiAsF 6 studied previously. Low salt solubility and separation of a metastable cubic CsCl-type polymorph of LiBr were established. The highest conductivity of ∼10 −4  S cm −1 at >50 °C was observed for heterogeneous samples comprising this phase. While the conductivity of PBAN–LiBr was lower than that of PBAN–LiClO 4 and PBAN–LiAsF 6 , this study provides a new insight into the nature of polymer electrolyte systems.