First-principles study of heterostructures of MXene and nitrogen-doped graphene as anode materials for Li-ion batteries

Two-dimensional heterostructures have attracted considerable attention as promising anode materials for lithium-ion batteries (LIBs). Here, we investigated the geometric and electronic properties of heterostructures composed of Ti2CT2 (T=O, F, OH) and N-doped graphene via first-principles density functional theory. Further, we investigated the Li adsorption and diffusion in heterostructures. We demonstrated that electron transfer between the two building blocks of the heterostructures dictates the strength of the adsorption of Li ions on surfaces. The direction and magnitude of electron transfer vary with the functional groups of MXene and N-doping types in N-doped graphene, which in turn influences the adsorption and diffusion of Li ions. We found that the heterostructure composed of Ti2CO2 and N-doped graphene has the strongest adsorption capacity for Li ions. Theoretical capacitances were estimated to be 378 and 417 mAhg−1 for Ti2CO2/GNG (graphitic N doping) and Ti2CO2/GNP (pyridinic N doping), respectively, which were larger than those of pristine Ti2CO2. These results suggest that heterostructures are promising anode materials for LIBs.