Identifying the Critical Anion-Cation Coordination to Regulate the Electric Double Layer for an Efficient...

Area of Science:

• Electrochemistry
• Materials Science
• Surface Chemistry

Background:

• Solid electrolyte interphase (SEI) formation is crucial for lithium metal anode stability.
• Understanding SEI evolution mechanisms is vital for rational control and improved battery performance.

Purpose of the Study:

• To elucidate the dominant factors controlling competitive reduction reactions during SEI construction on lithium metal anodes.
• To investigate the role of electric double layer (EDL) chemistry in SEI formation.
• To explore strategies for enhancing lithium metal anode protection.

Main Methods:

• Combined theoretical and experimental model investigations.
• Analysis of electric double layer (EDL) chemistry at the electrode/electrolyte interface.
• Evaluation of cation solvation and anion deficiency effects.

Main Results:

• EDL chemistry, beyond electrolyte thermodynamic stability, primarily controls SEI formation on lithium metal anodes.
• Lithium metal's negative surface leads to cation enrichment and anion deficiency in the EDL.
• Species within cation solvation shells are preferentially reduced, influencing SEI composition.

Conclusions:

• The EDL principle, cation solvation, and SEI formation are interconnected.
• Incorporating multi-valent cation additives is a promising strategy to improve lithium metal anode protection by guiding SEI formation.
• This work provides insights for targeted regulation of reactive alkali metal interfaces.