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.