Cyclic Ether Derived Stable Solid Electrolyte Interphase on Bismuth Anodes for Ultrahigh-Rate Sodium-Ion Storage.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Bismuth anodes offer high theoretical sodium-ion storage capacity.
• Stable solid electrolyte interphase (SEI) formation is crucial for battery performance.
• Ether solvents are known to facilitate SEI stability.

Purpose of the Study:

• To investigate the sodium-ion storage properties of bismuth anodes using cyclic tetrahydrofuran (THF) and 2-methyltetrahydrofuran (MeTHF) electrolytes.
• To analyze the impact of electrolyte solvation structure and SEI composition on sodium-ion storage kinetics.
• To understand the role of SEI properties in determining anode performance.

Main Methods:

• Electrochemical characterizations of bismuth anodes.
• Analysis of electrolyte solvation structure.
• Detailed SEI chemical composition analysis.
• Rate performance testing at various current densities.

Main Results:

• Bismuth anodes in both THF and MeTHF electrolytes show good rate performance at low current densities.
• THF-based electrolytes yield significantly higher reversible capacity at high current densities (316.7 mAh g⁻¹ in THF vs. 9.7 mAh g⁻¹ in MeTHF at 50 A g⁻¹).
• THF electrolytes form a thin, uniform, inorganic-rich SEI, while MeTHF electrolytes form a thicker SEI with more organic components.

Conclusions:

• The SEI composition and morphology critically influence sodium-ion storage kinetics.
• THF-based electrolytes are superior for high-rate sodium-ion storage with bismuth anodes due to optimized SEI formation.
• This research provides insights for developing advanced electrolytes for sodium-ion batteries.