Mechanism of Efficient Adsorption of Na Atoms on Electron-Deficient Doped MoS2 for Battery Electrodes

Due to the similarities in electrochemical and physicochemical properties of sodium and lithium, sodium-ion batteries are an attractive substitute for lithium-ion batteries. The selection of appropriate electrode materials for Na-ion batteries is an important step to achieve high stability and theoretical capacity. Here, the effects of heteroatom doping and charge variation on the ability of the MoS2 substrate to capture Na ions are studied using first-principles calculations. The results show that the interaction between Na ions and the MoS2 substrate is enhanced by electron deficiency or substituting a S atom with a dopant atom (X ) with fewer valence electrons (X= B, Al, Ga, In, C, Si, Ge, Sn, N, P, As, Sb). In contrast, adding electrons to the MoS2 substrate weakens its interaction with Na. We further analyze the diffusion barrier, open-circuit voltage, and theoretical capacity of hypothetical Na-ion batteries using doped X-MoS2 (X= heteroatom) as electrode materials. We find that Al- or Si-doped MoS2 can serve as good electrode materials for Na-ion batteries, with a high theoretical capacity that exceeds 700 mAh/g. This work provides practical guidance for the development of electrode materials of Na-ion batteries using two-dimensional materials.

Automated summary

This study investigates the effects of heteroatom doping and charge variation on the ability of MoS2 substrate to capture Na ions in sodium-ion batteries using first-principles calculations. The results show that Al- or Si-doped MoS2 can serve as good electrode materials with high theoretical capacity.