Surface-Sensitive NMR Detection of the Solid Electrolyte Interphase Layer on Reduced Graphene Oxide.

Area of Science:

• Materials Science
• Electrochemistry
• Analytical Chemistry

Background:

• A stable solid electrolyte interphase (SEI) is crucial for rechargeable battery longevity and performance.
• Understanding SEI formation at the molecular level requires advanced analytical techniques.

Purpose of the Study:

• To introduce dynamic nuclear polarization (DNP) as a novel method to enhance solid-state NMR (ssNMR) sensitivity for SEI analysis.
• To investigate SEI composition and structure in lithium-ion cells using DNP-enhanced ssNMR.

Main Methods:

• Utilized DNP to boost ssNMR sensitivity for SEI characterization.
• Employed ¹³C-enriched electrolyte solvents and natural abundance ¹³C measurements.
• Analyzed SEI on reduced graphene oxide (rGO) electrodes in Li-ion cells at 100 K.

Main Results:

• DNP significantly enhances the detection of outer SEI layer signals using natural abundance ¹³C.
• ¹³C-enriched electrolytes at 100 K allowed SEI differentiation without DNP due to high sensitivity.
• Inner and outer SEI layer compositions were successfully distinguished.

Conclusions:

• DNP-enhanced ssNMR is a powerful tool for sensitive SEI analysis in batteries.
• The study demonstrates the potential for detailed molecular-level SEI characterization.
• This approach can be extended to various electrode materials for improved battery research.