Ion transport in polycarbonate based solid polymer electrolytes: experimental and computational investigations

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Polycarbonates are emerging as promising host materials for solid polymer electrolytes (SPEs) in all-solid-state lithium batteries.
• Ion transport mechanisms in polycarbonates are less understood compared to conventional polyethers.

Purpose of the Study:

• To investigate the ionic transport behavior in SPEs based on poly(trimethylene carbonate) (PTMC) and its co-polymer with ε-caprolactone (CL).
• To compare the performance of polycarbonate-based SPEs with conventional polyether-based SPEs.

Main Methods:

• Fourier-transform infrared (FTIR) spectroscopy to analyze local coordination.
• Diffusion Nuclear Magnetic Resonance (NMR) to study ion mobilities and polymer domain structures.
• Potentiostatic polarization experiments to determine cationic transference numbers.
• Molecular Dynamics (MD) simulations for atomic-scale insights into structure-dynamics properties.

Main Results:

• FTIR confirmed preferential Li(+) coordination with ester carbonyl oxygen atoms in the P(TMC20CL80) co-polymer.
• NMR revealed higher ion mobilities in the co-polymer SPE and inferred locally oriented polymer domains.
• Potentiostatic polarization showed significantly higher cationic transference numbers in polycarbonate SPEs versus polyether SPEs.
• MD simulations corroborated preferential Li(+)-carbonyl oxygen coordination and the coupling of Li-ion and polymer chain dynamics.

Conclusions:

• Polycarbonate-based SPEs, particularly co-polymers, exhibit favorable ionic transport properties for lithium batteries.
• These materials demonstrate higher cationic transference numbers, suggesting improved battery performance.
• The study provides a comprehensive understanding of ion transport in polycarbonates, paving the way for advanced solid-state battery development.