In-plane staging in lithium-ion intercalation of bilayer graphene

Area of Science:

• Materials Science
• Electrochemistry
• Condensed Matter Physics

Background:

• Rechargeable lithium-ion batteries are crucial for energy storage.
• Optimizing battery performance requires understanding novel materials like bilayer graphene.
• The mechanisms of lithium intercalation in bilayer graphene are not well understood.

Purpose of the Study:

• To investigate the in-operando intercalation dynamics of lithium ions in bilayer graphene.
• To elucidate the underlying mechanisms governing lithium storage capacity in this material.
• To identify potential strategies for enhancing lithium storage in bilayer graphene.

Main Methods:

• Magnetotransport measurements were employed to study intercalation dynamics in real-time.
• Density Functional Theory (DFT) calculations were used to complement experimental findings.
• Analysis focused on distinct intercalation stages and Li-ion densities.

Main Results:

• Four distinct intercalation stages with well-defined Li-ion densities were identified.
• Rapid transitions between stages occurred across the entire device area within seconds.
• A critical AB to AA stacking transition at ~0.9·10^14 cm^-2 was observed, crucial for intercalation.
• Fully intercalated bilayer graphene forms a C14LiC14 compound with ~2.7·10^14 cm^-2 Li density.

Conclusions:

• The study reveals the specific mechanism and limitations of electrochemical intercalation in bilayer graphene.
• The findings highlight the importance of stacking transitions in determining storage capacity.
• This research provides a foundation for designing next-generation graphene-based energy storage devices.