Fundamental parameters governing ion conductivity in polymer electrolytes. (10th March 2019)

• Record Type: Journal Article
• Authors: Kisliuk, A.; Bocharova, V.; Popov, I.; Gainaru, C.; Sokolov, A.P.
• Is Part Of: Electrochimica acta. Volume 299(2019)
• Page Start: 191
• Page End: 196
• Publication Date: 2019-03-10
• Subjects: Polymer electrolytes -- Ion conductivity -- Shear modulus -- Haven ratio; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2018.12.143
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: We analyze conductivity of polymerized ionic liquids with focus on fundamental limitations hindering faster charge transport in polymer electrolytes. We emphasize that to achieve the required ionic conductivity ∼10 −3 S/cm in dry polymer electrolytes, a decoupling of ion transport from segmental dynamics is required. We demonstrate that two competing mechanisms control decoupling of ion transport: electrostatic interactions that dominates for small ions such Li, and elastic force that dominates for large ions. Our experimental results indeed confirm significant contribution of the elastic force to the energy barrier controlling transport of large ions. We also emphasize importance of ion-ion correlations that strongly affect charge transport (conductivity) even at the same ion diffusivity. Our analysis suggests that these correlations suppress ion conductivity in polymer electrolytes by about ten times. At the end, we formulate some ideas on design of polymer electrolytes with high ion conductivity. Highlights: Electrostatic and elastic forces control decoupled ion conductivity. Increase in shear modulus increases energy barrier for ion conductivity. Ion-ion correlations decrease conductivity in polymer electrolytes by ∼10 times.