Interface Synergistic Effect from Layered Metal Sulfides of MoS2/SnS2 van der Waals Heterojunction with Enhanced Li-Ion Storage Performance

Layered metal sulfides (LMSs) with larger interlayer spacing are suitable for Li+ intercalation/extraction and possess relatively higher theoretical specific capacity than commercial graphite. However, pure LMSs show inherent low conductivity and irreversible huge volume expansion in lithium uptakes. In this work, we introduce an interesting van der Waals heterojunction between two popular LMSs, i.e., MoS2/SnS2 van der Waals heterojunction grown on reduced graphene oxide (MoS2/SnS2-rGO), which is synthesized by a facile hydrothermal process. The MoS2/SnS2-rGO nanocomposite exhibits a remarkable interface synergistic effect due to the weak van der Waals interaction on their nanocrystalline, which leads to an enhanced energy storage performance compared with MoS2-rGO and SnS2-rGO. The MoS2/SnS2-rGO exhibits better cycling stability of 894 mAh g(-1) at 200 mA after 55 cycles and excellent rate performance of 590 mAh g(-1) at 1 A g(-1) for LIBs. This work proposes that weaker van der Waals interactions between the LMS can induce much more layer space for Li+ in LIBs, which might be another way to improve the storage performance of LIBs.