The Effect of Low-Molecular-Weight Poly(ethylene glycol) (PEG) Plasticizers on the Transport Properties of Lithium Fluorosulfonimide Ionic Melt Electrolytes
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- 作者：Olt E. Geiculescu ; Boutros B. Hallac ; Rama V. Rajagopal ; Stephen E. Creager ; Darryl D. DesMarteau ; Oleg Borodin ; Grant D. Smith
- 刊名：Journal of Physical Chemistry B
- 出版年：2014
- 出版时间：May 15, 2014
- 年：2014
- 卷：118
- 期：19
- 页码：5135-5143
- 全文大小：383K
- 年卷期：v.118,no.19(May 15, 2014)
- ISSN：1520-5207
文摘
The influence of low-molecular-weight poly(ethylene glycol) (PEG, Mw 鈮?550 Da) plasticizers on the rheology and ion-transport properties of fluorosulfonimide-based polyether ionic melt (IM) electrolytes has been investigated experimentally and via molecular dynamics (MD) simulations. Addition of PEG plasticizer to samples of IM electrolytes caused a decrease in electrolyte viscosity coupled to an increase in ionic conductivity. MD simulations revealed that addition of plasticizer increased self-diffusion coefficients for both cations and anions with the plasticizer being the fastest diffusing species. Application of a VTF model to fit variable-temperature conductivity and fluidity data shows that plasticization decreases the apparent activation energy (Ea) and pre-exponential factor A for ion transport and also for viscous flow. Increased ionic conductivity with plasticization is thought to reflect a combination of factors including lower viscosity and faster polyether chain segmental dynamics in the electrolyte, coupled with a change in the ion transport mechanism to favor ion solvation and transport by polyethers derived from the plasticizer. Current interrupt experiments with Li/electrolyte/Li cells revealed evidence for salt concentration polarization in electrolytes containing large amounts of plasticizer but not in electrolytes without added plasticizer.