A controllable flower-like FeMoO4/FeS2/Mo2S3 composite as efficient sulfur host for lithium-sulfur batteries

Abstract

As one of the most anticipated energy storage systems, the application of lithium-sulfur batteries is hindered by low conductivity of insoluble sulfur species (S8, Li2S2 and Li2S), the shuttle effect of soluble lithium polysulfides (Li2Sx, 4 = x ≤ 8) and the volume expansion of sulfur species during the cycling. To overcome these barriers, a tunable geometry of flower-like FeMoO4/FeS2/Mo2S3 composite is successfully investigated using simple one-step solvothermal technique. Fe-based sulfides with good conductivity and Mo-based sulfides with the efficient ability of catalytic sulfur species conversion are promising sulfur host for high performance lithium-sulfur batteries (LSBs). It should be noted that this is first time to introduce FeMoO4 as polysulfides anchoring material into the lithium-sulfur system. Consequently, the flower-like composite with 79 wt % sulfur loading exhibits a high initial capacity of 1600 mA h g−1 and a reversible capacity of 781 mAh g−1 after 300 cycles at 1 C. Even at a high rate of 10 C, a capacity of 421 mAh g−1 is maintained after 300 cycles.