Establishing the Field-Flow Competition Model to Decipher the Nonmonotonic Interfacial Li⁺ Dynamic Process for...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Bulk electrolyte solvation is well-understood, but interfacial solvation dynamics under electric and concentration fields remain unclear.
• Interfacial solvation critically influences cathode-electrolyte interphase (CEI) formation in lithium-ion batteries.
• Elucidating dynamic interfacial behavior is crucial for advancing battery performance.

Purpose of the Study:

• To investigate the dynamic evolution of interfacial Li+ population during battery operation.
• To establish a mechanistic framework correlating interfacial solvation with CEI formation.
• To develop strategies for engineering robust CEI layers for enhanced battery cycling stability.

Main Methods:

• In situ electrochemical spectroscopy was used to monitor interfacial Li+ population.
• A field-flow competitive regulation model was developed to explain Li+ dynamics.
• A potential-modulated activation protocol was designed based on mechanistic insights.

Main Results:

• A multistage, nonmonotonic "enrichment-depletion-re-enrichment" trend of interfacial Li+ was observed.
• The model successfully correlated interfacial electric fields and delithiation-induced Li+ inflow with solvation changes.
• The developed protocol bypassed detrimental Li+/anion-depletion phases, forming a mechanically robust CEI.
• Enhanced cycling stability of high-voltage cathodes was achieved.

Conclusions:

• Dynamic interfacial solvation engineering is critical for designing advanced energy storage systems.
• Understanding and controlling interfacial Li+ behavior directly impacts CEI composition and battery longevity.
• This work provides a foundation for rational design of electrode/electrolyte interfaces in next-generation batteries.