Interfacial Design on Graphene-Hematite Heterostructures for Enhancing Adsorption and Diffusion towards Superior Lithium Storage

Hematite (alpha-Fe2O3) is a promising electrode material for cost-effective lithium-ion batteries (LIBs), and the coupling with graphene to form Gr/alpha-Fe2O3 heterostructures can make full use of the merits of each individual component, thus promoting the lithium storage properties. However, the influences of the termination of alpha-Fe2O3 on the interfacial structure and electrochemical performance have rarely studied. In this work, three typical Gr/alpha-Fe2O3 interfacial systems, namely, single Fe-terminated (Fe-O-3-Fe-R), double Fe-terminated (Fe-Fe-O-3-R), and O-terminated (O-3-Fe-Fe-R) structures, were fully investigated through first-principle calculation. The results demonstrated that the Gr/Fe-O-3-Fe-R system possessed good structural stability, high adsorption ability, low volume expansion, as well as a minor diffusion barrier along the interface. Meanwhile, investigations on active heteroatoms (e.g., B, N, O, S, and P) used to modify Gr were further conducted to critically analyze interfacial structure and Li storage behavior. It was demonstrated that structural stability and interfacial capability were promoted. Furthermore, N-doped Gr/Fe-O-3-Fe-R changed the diffusion pathway and made it easy to achieve free diffusion for the Li atom and to shorten the diffusion pathway.

Automated summary

This study investigated the characteristics of three typical Gr/α-Fe2O3 interface systems through first-principle calculation, and found that the Gr/Fe-O-3-Fe-R system exhibited good structural stability and a minor diffusion barrier. Additionally, the introduction of heteroatoms like N-doped Gr further improved the interfacial capability and altered the diffusion pathway for lithium atoms.