Green synthesis of fig–like Li2S–Mo@C nanocomposites for advanced lithium–sulfur batteries

• A fig–like Li 2 S–Mo@C nanocomposites is designed and prepared for Li–S batteries. • The fig–like Li 2 S–Mo@C exhibits excellent electrochemical performance. • The role of carbon shell, Mo nanodots and fig–like structure is revealed. Lithium sulfide (Li 2 S) is considered as a promising alternative for the intercalation–type cathode materials because of its high theoretical specific capacity (1166 mAh g –1 ). However, the large–scale application of Li 2 S is limited by its intrinsic low electronic/ionic conductivity and severe shuttle effect of polysulfides. Herein, we report a facile and green method to the in–situ synthesis of Li 2 S–molybdenum (Mo) nanocomposites at room temperature by mechanochemical reaction of lithium hydride with molybdenum sulfide. The fig–like carbon coated Li 2 S–Mo (Li 2 S–Mo@C) nanocomposite with core–shell structure exhibits a low initial activation barrier of 2.51 V, high reversible capacity of 742 mAh g − 1 after 70 cycles at 0.2 A g − 1 and excellent cycling stability over 500 cycles at 1.0 A g − 1 . According to density functional theory calculation and experimental studies, the excellent electrochemical performance of fig–like Li 2 S–Mo@C nanocomposite can be attributed to the increased electronic/ionic conductivity, strong adsorption ability and catalytic conversion of lithium polysulfides, resulting from the synergistic effects of Mo nanodots and, carbon shell and their nanostructure. This work provides a new idea for developing large–scale applications of Li 2 S–based electrodes.