Amorphous SnS x (1 < x < 2) Anode with a High-Rate Li Alloying Reaction for Li-Ion Batteries.

Here, we report the conversion of bulk Li alloying anode reactions into surface reactions by the construction of amorphous structured SnS x active materials encapsulated in robust carbon nanofiber anodes. The high-temperature phase transformation from SnS to SnS 2 is used to construct the SnS x (1 < x < 2) active material with an amorphous structure and ultra-tiny particle size, leading to a decreased Li + diffusion path, weakened volume change ratio, but considerably enhanced capacitance. The amorphous structure changes the Li-storage mechanism from Li-intercalation to the surface reaction, which endows each active particle with a rapid (de)lithiation characteristic. As a result, the high-rate (dis)charge property with a long-term cycle life is obtained for SnS x @NC, which delivers an excellent rate capability of 633.4 mAh g -1 under 7 A g -1 and a capability retention of 785.2 mAh g -1 after 1600 cycles under 2 A g -1 .