Misfit layer SnTiS3: An assemble-free van der Waals heterostructure SnS/TiS2 for lithium ion battery anode

Abstract

Misfit layer SnTiS3 (STS) crystal as a bulk van der Waals (vdW) heterostructure SnS/TiS2 is developed as a superior anode material for lithium-ion batteries (LIBs). STS can combine the advantages of metallic character of TiS2 layers and high lithium-storage of SnS layers. Moreover, graphene oxide (GO) is adopted to support STS via a hand-grinding route. A strong binding between STS and GO is conducive to decreasing the crystalline domain size of STS. Besides, the in-situ electrochemical reduction of GO nanosheets during the first cycling could offer a conductive network for both ions and electrons. Consequently, the electrochemical performance of STS/GO is superior than that of pristine STS and STS/rGO (rGO = reduced GO), and outstanding among the latest reports of SnS- or TiS2-based on LIBs anodes. Specifically, STS/GO anode delivers a capacity of 614 mA h g−1 at 2.0 A g−1 after 1000 cycles, as well as a high rate capability due to the dominated surface-capacitive contribution. Furthermore, the combination of in-situ and ex-situ powder X-ray diffraction patterns unequivocally reveals a conversion-alloy mechanism in STS anode upon lithiation/delithiation.