Phase transformation and sulfur vacancy modulation of 2D layered tin sulfide nanoplates as highly durable anodes for pseudocapacitive lithium storage

Abstract Despite the fulfilling progress in fabricating metal chalcogenides-based battery electrodes, most effort focuses on construction of hybrid architectures and/or foreign elemental doping for improving electrochemical performance. In this work, we report a self-template strategy to synthesize hexagonal SnS2 and orthorhombic SnS nanoplates with abundant S vacancies as advanced anode materials of lithium-ion batteries (LIBs). Phase evolution from hexagonal SnS2 to orthorhombic SnS by thermal annealing is investigated. The resultant tin sulfide nanoplates featuring abundant S vacancies and decreased bandgaps can provide more active sites, higher Li+-ion diffusion mobility and better electronic conductivity, which are beneficial for improving electrochemical reaction kinetics. Consequently, both the S-vacancy-rich SnS2 (SVR-SnS2) and the SVR-SnS nanoplates show significantly enhanced cycling performance and rate capability compared with the interlayer-expanded SnS2 (IE-SnS2) nanoplates. Remarkably, the SVR-SnS nanoplates can exhibit outstanding rate capability (510 mAh g−1 at 10 A g−1) and excellent long-term cycling performance. A reversible capacity as high as 765 mAh g−1 at a high current of 2 A g−1 can be delivered even after 1200 cycles. It is the best cycling performance of SnS-based electrodes for LIBs to date. Besides the benefits from S vacancies, the pseudocapacitive contribution is also responsible for the fast and stable lithium storage capability. The present work provides a new strategy for modulating 2D layered tin sulfide nanoplates as promising anode materials for LIB applications.