Three-dimensional micro-nanostructures based on binary transitional metal sulfides with doped carbon protector enabled high-performance and safe batteries.

The lack of suitable Li+ reservoirs and the risk of thermal runaway have hindered the extended use of lithium-ion batteries. Although utilizing Li4Ti5O12 or TiO2 can improve the thermal safety, their low theoretical capacities compromise the electrochemical performance of the cell. In this study, a three-dimensional micro-nanostructure based on binary transitional metal sulfides (TMSs) with a doped carbon protector (SnS/Co9S8@HC) is designed. When operating at 0.1-1 A g-1, the SnS/Co9S8@HC cell exhibits a high inceptive capacity of 1104.8 mAh g-1 with a high coulomb efficiency of 97.1%. Even after 1000 cycles, it delivers a relatively-high capacity of 450.3 mAh g-1, indicating a low capacity decay rate of 0.033% per cycle (from the 2nd to the 1000th cycle). The thermal runaway actions of the cells with graphite and SnS/Co9S8@HC anodes are investigated. The results demonstrate that the cell with the SnS/Co9S8@HC anode exhibits a significantly reduced maximum thermal runaway temperature of 473.5 ± 6.2℃ and maximum temperature increasing rate of 15.1 ± 0.6 °C min-1 compared to the graphite cell. This indicates that SnS/Co9S8@HC cell holds higher thermal safety. The potential of SnS/Co9S8@HC as sodium ion batteries anode is also investigated. The results indicate an initial capacity of 631.7 mAh g-1, with a low capacity decay rate of 0.063% per cycle when operating at 2 A g-1. This work may be enlightening for constructing multi-phase TMSs based hierarchical structure towards superior and safe energy storage.