Sb Doping and Amorphization Co-Induced High Capacity and Excellent Durability of Tin Sulfide-Based Anode for K-Ion Batteries.

The carbon nanotubes (CNTs) supported amorphous Sb doped substoichiometric tin dulfide (Sb─SnS ) with a carbon coating (the C/Sb─SnS @CNTs-500) is reported to be an efficient anode material for K storage. The formation of the C/Sb─SnS @CNTs-500 is simply achieved through the thermally induced desulfurization of tin sulfide via a controlled annealing of the C/Sb─SnS @CNTs at 500 °C. When used for the K storage, it can deliver stable reversible capacities of 406.5, 305.7, and 238.4 mAh g at 0.1, 1.0, and 2.0 A g , respectively, and shows no capacity drops when potassiated/depotassiated at 1.0 and 2.0 A g for >3000 and 2400 cycles, respectively. Even at 10, 20, and 30 A g , it can still deliver stable reversible capacities of 138.5, 85.1, and 73.8 mAh g , respectively. The unique structure, which combines the advantageous features of carbon integration/coating, metal doping, and desulfurization-induced amorphous structure, is the main origin of the high performance of the C/Sb─SnS @CNTs-500. Specifically, the carbon integration/coating can increase the electric conductivity and stability of the C/Sb─SnS @CNTs-500. The density function theory calculation indicates that the Sb doping and the desulfurization can facilitate the potassiation and increase the electric conductivity of Sb─SnS . Additionally, the desulfurization can increase the K diffusivity in Sb─SnS .