Solid state NMR study of sodium thiocyanate/poly(ethylene oxide) electrolytes

Area of Science:

• Materials Science
• Polymer Chemistry
• Solid-State NMR Spectroscopy

Background:

• Polyethylene oxide (PEO) and sodium thiocyanate (NaSCN) mixtures are relevant for various applications, including solid electrolytes.
• Understanding their morphology and ion dynamics is crucial for optimizing material properties.

Purpose of the Study:

• To characterize the morphology and dynamics of NaSCN-PEO mixtures using solid-state Nuclear Magnetic Resonance (NMR).
• To determine the phase composition and stoichiometry of the crystalline complex.
• To investigate the dynamics of polymer chains and the environments of sodium cations.

Main Methods:

• Solid-state NMR measurements, including 1H, 13C, and 23Na NMR.
• Magic Angle Spinning (MAS) NMR for spectral resolution.
• Selective 13C-MAS experiments to determine sample composition.
• 1H- and 13C-spin-lattice relaxation time measurements for domain size and dynamics.
• 23Na-MAS spectra and 2D nutation experiments to probe sodium cation environments.

Main Results:

• Selective 13C-MAS experiments successfully determined the composition and stoichiometry of (PEO)nNaSCN samples and crystalline complexes.
• Spin-lattice relaxation times provided estimates of domain dimensions and insights into polymer chain dynamics.
• 23Na NMR experiments identified distinct environments for sodium cations based on their quadrupolar interactions.

Conclusions:

• Solid-state NMR is effective for characterizing the complex morphology and dynamics of NaSCN-PEO mixtures.
• The study elucidated the distribution of phases, stoichiometry, and the behavior of polymer chains and sodium ions within these materials.