Boosting magnesium storage in MoS2via a 1T phase introduction and interlayer expansion strategy: theoretical prediction and experimental verification

Abstract

Rechargeable magnesium batteries (RMBs) are considered as potential alternative future energy-storage systems. However, due to the lack of a suitable cathode material, they face daunting challenges in practical applications. Herein, by density functional theory (DFT) calculations, it was found that the 1T phase of MoS₂ is helpful for Mg-storage improvement due to the enrichment in Mg-storage active sites and good conductivity. It was also found that expanding the layer spacing of 1T MoS₂ is beneficial to enhancing the diffusion and migration ability of Mg ions between layers. To verify these calculation results, interlayer-expanded 1T/2H MoS₂ nanosheets with a high 1T phase content were successfully fabricated through a facile solvothermal method. Compared with the pure 2H MoS₂, the interlayer-expanded 1T/2H MoS₂ cathode exhibited a significantly higher reversible capacity of 127 mA h g⁻¹ and excellent cyclic stability. Its capacity retention was close to 90% after 200 cycles at 50 mA g⁻¹. Further, the charge–discharge mechanism was investigated and is explained. Such interlayer-expanded 1T/2H MoS₂ nanosheets with excellent properties represent an ideal candidate material for the electrode of RMBs.