An efficient Mo-doped VS2 cathode material for rechargeable magnesium batteries

Although rechargeable magnesium batteries (RMBs) offer high volumetric energy density and intrinsic safety, their practical application and development are severely hindered by the sluggish diffusion of Mg 2+ ions due to the strong electrostatic interaction with host structure of cathode materials. Herein, a Mo-doped vanadium disulfide (MVS) has been developed to improve Mg 2+ diffusion and promote development of RMBs. Research results confirm that doping an appreciate amount of Mo can expand the interlayer spacing of (001) crystal plane in vanadium disulfide (VS 2 ), induce rich defects, and improve its surface area and electronic conductivity, thus facilitating the diffusion of Mg 2+ and electrode reaction kinetics. Consequently, the battery Mg//MVS delivers a discharge capacity of 292.5 mAh g −1 at current density of 100 mA g −1 and excellent rate capability. Moreover, it can also charge and discharge stably 1400 cycles at 1000 mA g −1 with near 100% Coulomb efficiency. In addition, electrochemical and ex situ characterizations confirm that doping Mo does not change the cathode reaction mechanism but significantly increases the diffusion coefficient of Mg 2+ ions, and improves structural stability and reaction reversibility during charge-discharge. This work establishes a viable structural-regulation strategy for developing high-performance cathode of RMBs and also proposes some fundamental insights into modulation mechanism of next-generation multivalent ion storage systems.