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Solid-state Graft Copolymer Electrolytes for Lithium Battery Applications
Published on: August 12, 2013
Polymer chain organization in tensile-stretched poly(ethylene oxide)-based polymer electrolytes
Christopher M Burba1, Lauren Woods, Sarah Y Millar
1Department of Natural Sciences, Northeastern State University, Tahlequah, OK.
Electrochimica Acta
|December 21, 2011
Summary
Stretching poly(ethylene oxide)-lithium trifluoromethanesulfonate polymer electrolytes aligns polymer chains, enhancing ion conduction pathways. This orientation primarily occurs between 150% and 250% strain, regardless of salt concentration.
Area of Science:
- Materials Science
- Polymer Chemistry
- Electrochemistry
Background:
- Polymer electrolytes are crucial for solid-state batteries.
- Understanding polymer chain orientation is key to optimizing ion conductivity.
- Poly(ethylene oxide)-lithium trifluoromethanesulfonate (PEO-LiCF3SO3) is a promising polymer electrolyte system.
Purpose of the Study:
- To investigate the orientation of polymer chains in tensile-stretched PEO-LiCF3SO3.
- To correlate chain orientation with strain and salt composition.
- To understand the impact of orientation on lithium ion conduction.
Main Methods:
- Polarized infrared (IR) spectroscopy was used to analyze polymer chain orientation.
- Two-dimensional correlation FT-IR spectroscopy identified domain alignment.
- Quantitative measurements used dichroic IR spectroscopy.
- Experiments were conducted at various strain levels and salt compositions (EO:Li ratios of 20:1, 15:1, 10:1).
Main Results:
- Both crystalline PEO and P(EO)3LiCF3SO3 domains align at similar rates during stretching.
- Predominant polymer chain orientation occurs between 150% and 250% strain.
- Further stretching to 300% showed minimal additional orientation, with PEO domains slightly more oriented.
- Spectroscopic data support stretching-induced melt-recrystallization.
Conclusions:
- Stretching aligns polymer helices parallel to the stretch direction, facilitating ion migration.
- Alignment reduces the number of inter-grain hops required for lithium ion conduction.
- Optimized polymer chain orientation in PEO-based electrolytes can significantly improve battery performance.
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