Subnanometric Pores of the Solid Electrolyte Interphase Layer for Sodium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Sodium-ion batteries (SIBs) are a sustainable alternative to lithium-ion batteries.
• Understanding the solid electrolyte interphase (SEI) is crucial for SIB performance but remains insufficient.
• Current SEI models lack detailed characterization of subnanometric pores.

Purpose of the Study:

• To develop a novel probing approach for characterizing subnanometric SEI pores in SIBs.
• To elucidate the mechanism of Na+ transport through the SEI.
• To investigate the impact of solvent salts on SEI architecture.

Main Methods:

• Utilized redox mediator molecules as probes for SEI characterization.
• Employed electrochemical analysis and differential electrochemical mass spectrometry (DEMS).
• Incorporated theoretical calculations to analyze SEI structure and ion transport.

Main Results:

• Revealed that Na+ transport in SIBs occurs via diffusion channels within the SEI.
• Demonstrated the influence of different solvent salts on the SEI's structural properties.
• Provided a powerful characterization tool for subnanometric SEI pores.

Conclusions:

• The findings advance fundamental knowledge beyond classical SEI models.
• The developed probing approach offers a new method for SEI analysis in SIBs.
• Established principles for selecting electrolytes to optimize SEI formation and battery performance.