Vacancy enhanced Li, Na, and K clustering on graphene

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Metallic dendrite formation in alkali metal-ion batteries compromises cycle life and safety.
• Surface defects are suspected to promote inhomogeneous metal nucleation, but atomic-scale mechanisms are unclear.

Purpose of the Study:

• Investigate the influence of carbon monovacancies (V_C) on alkali metal (Li, Na, K) clustering on graphene.
• Clarify defect-facilitated pathways for metal clustering and subsequent dendrite formation.

Main Methods:

• First-principles calculations were employed to study alkali metal clusters (n=1-12) on pristine and defective graphene surfaces.
• Analyzed the stability of metal clusters and their binding interactions with graphene.

Main Results:

• On pristine graphene, Li cluster formation is hindered, K clustering is suppressed, and Na exhibits spontaneous clustering.
• Carbon monovacancies stabilize small alkali metal clusters (n ≤ 3) by enhancing surface binding and modifying charge localization.
• Vacancies facilitate early-stage nucleation for Li, promote Na growth at lower loadings, and favor K clustering at small sizes.

Conclusions:

• Carbon monovacancies significantly alter alkali metal clustering behavior on graphene, promoting dendrite precursor formation.
• Atomistic insights into defect-facilitated clustering can guide the design of dendrite-resistant carbon anodes for improved battery performance and safety.