Li absorption and intercalation in single layer graphene and few layer graphene by first principles

Area of Science:

• Materials Science
• Computational Chemistry
• Solid State Physics

Background:

• Lithium-ion battery anodes rely on carbon materials like graphite.
• Understanding lithium interaction with graphene is crucial for next-generation energy storage.
• Graphene's unique structure presents distinct lithium absorption and intercalation behaviors compared to bulk graphite.

Purpose of the Study:

• To comprehensively investigate lithium absorption and intercalation in single-layer and few-layer graphene using first-principles calculations.
• To compare the lithium storage capacity of graphene materials with that of bulk graphite.
• To elucidate the mechanisms and stable phases of lithium intercalation in few-layer graphene.

Main Methods:

• Utilizing the cluster expansion method for systematic search of low-energy configurations in single-layer graphene.
• Developing and calibrating a semiempirical potential incorporating van der Waals interactions for few-layer graphene.
• Performing first-principles calculations to analyze lithium-graphene interactions and intercalation pathways.

Main Results:

• Lithium absorption is not thermodynamically stable on defect-free single-layer graphene surfaces.
• Defect-poor single-layer graphene exhibits significantly lower lithium storage capacity than bulk graphite.
• Identified key lithium intercalation mechanisms and stable phases in few-layer graphene, bridging the gap between single-layer graphene and bulk graphite.

Conclusions:

• Single-layer graphene, without defects, is unsuitable for direct lithium absorption.
• Few-layer graphene offers a promising pathway for lithium intercalation, with performance dependent on layer number and structure.
• The study provides fundamental insights into lithium storage in layered carbon materials, guiding the design of advanced battery anodes.