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.