Graphene/C2N lateral heterostructures as promising anode materials for lithium-ion batteries

Abstract

Two-dimensional (2D) heterostructures have been proposed as potential anode materials for lithium-ion batteries due to their large surface areas and excellent electronic properties. In this study, we employ first-principles calculations to investigate the structural stability, electronic properties, and ion diffusion behaviors of 2D graphene/C₂N lateral heterostructures. Three species of (5, 26), (11, 26), and (17, 26) heterostructures are chosen to explore the effects of graphene components on electronic properties. The results show that graphene/C₂N lateral heterostructures exhibit good dynamic stability due to a small lattice mismatch and strong chemical interaction at the heterojunction interface. By introducing zero-gap graphene, these heterostructures acquire good electronic conductivity with small direct band gaps. The component ratio of graphene can significantly tune the band gap, showing a monotonic decrease as the ratio increases. Moreover, the introduction of C₂N components can greatly improve the lithium capacities of heterostructures. Small diffusion energy barriers (0.257–0.273 eV) and a low average operating voltage of 0.758 V are observed in graphene/C₂N heterostructures. The effects of graphene components and valence states on Li migration are discussed. Our results demonstrate that the graphene/C₂N lateral heterostructure can effectively combine the advantages of graphene and the C₂N monolayer, showing great promise as an anode material for lithium-ion batteries.