Silicon-protected, vertically grown MoS2 nanosheets for high-performance thin-film Li-ion batteries

Abstract

Silicon-coated molybdenum sulfide nanosheets were prepared in a thin-film shape (Si–MoS2 TFs) through metal organic chemical vapor deposition (MOCVD) and radio frequency (RF) sputtering. By using MOCVD, the MoS2 thin films composed of nanosheets were vertically grown on stainless steel substrates. To address the problem of polysulfide dissolution and shuttling effect of MoS2 during discharge and charge reactions in thin-film Li-ion batteries, the entire surfaces of MoS2 TFs were covered with silicon layers using RF sputtering. Compared with pristine MoS2 TFs without protection, the Si–MoS2 TFs showed excellent reversibility with a high capacity of ∼2000 mAh g−1 for 500 cycles in thin-film Li-ion batteries. Both materials – MoS2 and Si – were synergistically taken into account to enhance the ability to store Li ions in the host structures and complement each other during repeated conversion and alloying reactions. The underlying reaction principle was elucidated, which provides insight into developing MoS2-based thin-film cathodes.