Controlled defective engineering of MoS_2 nanosheets for rechargeable Mg batteries

摘要

Developing high energy density and high stability rechargeable battery for higher power output devices is urgent but challenging. Rechargeable Mg batteries are justified in raising high hopes for grid-scale energy storage. However, the practical application of rechargeable Mg batteries is severely limited by electrolytes and anode materials, especially cathode materials. One of the inherent challenges with rechargeable Mg batteries is how to accelerate the diffusion of Mg2+ in cathode materials. Various approaches are currently in their infancy. Herein, 2D (2 dimension) MoS2 nanosheets of controlled defective degree prepared via hydrothermal method have been investigated for assembled battery systems. The defective structures have been characterized by XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy) and HRTEM (high-resolution transmission electron microscopy), and the cathode performance also been evaluated by cyclic voltammetry, galvanostatic charge/discharge, rate performance and cycling performance tests and electrochemical impedance spectra. The results show that the introduction of defects into MoS2 nanosheets improves the diffusion of Mg2+, resulting an excellent electrochemical performances in rechargeable Mg batteries. The discharge specific capacity reaches up to 152 mAh g(-1) while the charge-transfer resistance (R-ct) only for 2000 Omega, when assembling defective MoS2 as cathode at Mo:S = 1:4. This work highlights the potential applications of defective structure in rechargeable Mg batteries.