Tuning lithium storage and transport via graphene line defects: a first-principles study

The growing demand for high-performance rechargeable batteries calls for the development of advanced electrode materials, with carbon-based materials remaining a focal point for lithium-ion batteries (LIBs). Among them, graphene stands out for its high electrical conductivity, large surface area, and excellent chemical stability, yet suffers from inherent limitations as an electrode material, for its low practical capacity and sluggish ion transport kinetics. Recent studies have shown that point defects in graphene can markedly enhance capacity and reduce migration barriers. Motivated by this, we investigate the effects of line defects on graphene for LIB applications, as such defects are likely to be introduced in a controllable manner. Using first-principles calculations, we systematically examine four experimentally or theoretically reported line defects-5-8-5, 55-77, t5t7, and 4-8-and their influence on Li storage and diffusion. Our results show that these line defects substantially enhance the lithium binding energies and reduce the diffusion barriers compared with pristine graphene, which may be beneficial for mitigating localized Li accumulation. Besides, the theoretical capacities are approximately estimated, and a substantial enhancement is observed compared with pristine graphene. Furthermore, the defects introduce unique migration pathways that accelerate ion transport. These insights highlight defect engineering as a promising strategy for optimizing graphene-based anodes in next-generation high-performance lithium batteries.