First-principles study on the electrochemical properties of Na-ion-intercalatable heterostructures formed by transitional metal dichalcogenides and blue phosphorus

Abstract

Extensive first-principles calculations have been performed to examine the electrochemical properties of Na-ion-intercalatable heterostructures formed by transitional metal dichalcogenides (MS2, where M = Ti, V, Nb and Mo) and blue phosphorus (BlueP), which have been reported as potential anode materials for rechargeable sodium-ion batteries. Upon formation of heterostructures, much improved structural stabilities have observed compared with the pristine MS2 and BlueP. Metallic T-TiS2, T-MoS2, H(T)-VS2 and H(T)-NbS2 would retain the conductive character after formation of heterostructures with BlueP, however, H-TiS2/BlueP and H-MoS2/BlueP would undergo a semiconductor to metallic transition accompanied by Na intercalation. Moreover, the presence of relatively low diffusion barriers ranging from 0.04 eV to 0.08 eV, coupled with the suitable average open-circuit voltage spanning from 0.12 eV to 0.89 eV, guarantee exceptional charge-discharge rates and ensure the safety of battery performance. Among these heterostructures, H(T)-NbS2/BlueP and T-TiS2/BlueP exhibit best Na adsorption ability of up to 4 layers, corresponding to theoretical capacities of 570.2 and 746.7 mAh/g, respectively. These encouraging properties indicate that T-TiS2/BlueP and H(T)-NbS2/BlueP could serve as suitable anode materials for high-performance sodium-ion batteries.