Fluoride-Ion Polymer Electrolytes Constructed from Poly(ethylene oxide) and a Fluorohydrogenate Ionic Liquid
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Solid-state polymer electrolytes containing poly(ethylene oxide) (PEO) and a tetrabutylammonium bifluoride (TBAHF 2 ) ionic liquid are evaluated for fluoride-ion battery applications. TBAHF 2 readily mixes with PEO, and the resulting polymer electrolytes deliver ionic conductivities as high as 3 × 10 –6 S cm –1 at 293 K. Brillouin spectroscopic measurements reveal heterogeneity in the longitudinal acoustic mode frequency, which implies nonuniform distributions of ionic liquid in the polymer electrolyte. This is prominent for low salt contents where heterogeneity is exacerbated. X-ray scattering and DSC measurements reinforce this observation. Crystalline domains exist for all compositions investigated, but their size and prevalence vary with salt content. Pure TBAHF 2 is characterized by HF 2 – coordination to the cation via butyl chain C–H groups. These interionic associations are disrupted upon mixing with PEO. A combination of vibrational spectroscopy and quantum chemical calculations suggest that the polymer and salt interactions are mediated by weak C–H···FHF – contacts between the anion and CH 2 groups along the PEO backbone. It is likely that the relative strength of the PEO···HF 2 – and TBA + ···HF 2 – interactions may be tuned through chemical modifications to the cation to tailor polymer electrolyte properties. In this way, fluorohydrogenate ionic liquids represent a fertile research area for developing fluoride-ion polymer electrolytes.
Source: ACS Applied Polymer Materials
Author: Christopher M. Burba
Institution: Northeastern State University
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Funder: Office of Naval Research
Award: G7837013872
OpenAlex ID: W4414164131