Compatibility of Molybdenum Disulfide and Magnesium Fluorinated Alkoxyaluminate Electrolytes in Rechargeable Mg Batteries

Abstract

AbstractMolybdenum disulfide (MoS2)‐based cathodes have exhibited good electrochemical reactions in all phenyl complex (APC) electrolytes. However, APC electrolytes are highly corrosive and susceptible to oxidation. Alternatively, magnesium fluorinated alkoxyaluminate electrolyte (Mg[Al(HFIP)4]2) is a pioneering chloride‐free electrolyte with remarkable electrochemical activity in rechargeable Mg batteries (RMBs). This study aims to investigate the compatibility of various MoS2 nanomaterials with Mg[Al(HFIP)4]2 in RMBs. Seven MoS2 nanomaterials were synthesized under different hydro/solvothermal conditions and evaluated as cathode materials in RMBs. The results revealed that the electrochemical activity of the as‐synthesized MoS2 in RMBs significantly varied and MoS2 with high content of 1T‐phase (M5) exhibited the best specific capacity of ca. 35 mAh g−1. Heteroatom doping, graphene oxide (GO) incorporation, and dual‐salt electrolytes were employed to enhance the electrochemical performance of M5. The electrochemical tests showed that all doped‐MoS2 and GO‐MoS2 delivered poor specific capacities (<20 mAh g−1), properly due to the disorder of the cathode material and the entrapment of Mg2+ ions. In contrast, dual‐salt electrolytes (0.3 M Mg[Al(HFIP)4]2/0.3 M LiCl) improved the initial specific capacity by 242 %. This is attributed to the preferential intercalation of Li+ ions that reduces the diffusion energy barrier and facilitates the intercalation of Mg+2 ions.