Enhancing Mg²⁺ and Mg²⁺/Li⁺ Storage by Introducing Active Defect Sites and Edge Surfaces in MoSe₂

Abstract

Recently, Mg‐ion batteries (MIBs) and Mg−Li hybrid ion batteries (MLIBs) are deemed as potential energy‐storage devices. However, due to the insufficient storage sites of Mg2 + in the cathode, MIBs show a low reversible capacity. For MLIBs, the property is also seriously restricted due to the main Li+ intercalation reaction and less Mg2+ intercalation reaction. Herein, ultrathin MoSe2 nanosheets with enriched atomic defects and exposed edge surfaces are prepared by the hydrothermal method and subsequent hydrogen treatment. It is found that the Mg2+ storage performance is markedly enhanced, and Mg2+/Li+ co‐intercalation can be achieved. Density functional theory (DFT) calculation shows that, by introducing a large number of atomic defects and edge exposed surfaces in the ultrathin MoSe2 nanosheets, the Mg2+ storage sites are increased, and the diffusion and migration ability of Mg2+ and Li+ are improved, resulting in a significant property improvement. Further, the Mg2+ intercalation in MIBs and Mg2+/Li+ co‐intercalation in MLIBs are confirmed. The discharge‐charge mechanisms only based on the intercalation reactions for both MIBs and MLIBs are also revealed.

Core-Shell CuS@MoS2 Cathodes for High-Performance Hybrid Mg-Li Ion Batteries

“…The research and development of high energy density, high power density, cheap and clean energy conversion or energy storage devices are of great significance to the sustainable development of human beings. [1][2][3][4][5][6] Lithium-ion batteries are widely used because of high energy density and portable energy storage. However, the problems of security, environment and low utilization of lithium resources still exist.…”

Facile Fabrication of High-Power Molybdenum Diselenide Cathode for Rechargeable Magnesium Batteries

“…The peak at 246 cm –1 is assigned to the out-of-plane Mo–Se mode (A 1g ) of the 2H phase, which is observed in 2H-MoSe 2 and L-MoSe 2 but not obvious in R-MoSe 2 . The peaks at 200 and 355 cm –1 corresponding to the 1T phase are present in both R-MoSe 2 and L-MoSe 2 . The XRD and Raman results demonstrate the formation of both 1T and 2H phases for MoSe 2 , and the 1T phase content increases with an increasing amount of hydrazine hydrate used for the solvothermal synthesis.…”

“…The peaks at 200 and 355 cm −1 corresponding to the 1T phase are present in both R-MoSe 2 and L-MoSe 2 . 21 The XRD and Raman results demonstrate the formation of both 1T and 2H phases for MoSe 2 , and the 1T phase content increases with an increasing amount of hydrazine hydrate used for the solvothermal synthesis.…”

“…Typically, MoSe 2 has such a layer structure with van der Waals interaction connecting the Se–Mo–Se layers, forming an interlayer spacing of 0.65 nm along the c axis . Previous reports show that the Mg-storage performance of MoSe 2 could be improved by using hybrid battery systems, introducing active defect sites and interlayer expansion. , Actually, two kinds of phases, 2H and 1T, are usually encountered for MoSe 2 . Different from the semiconductive 2H phase, 1T phase MoSe 2 exhibits negligible band gap and high conductivity favoring fast electron conduction .…”