Synthesis of TiO2/S@PPy composite for chemisorption of polysulfides in high performance Li-S batteries

The commercial application of lithium-sulfur (Li-S) battery is hampered by the insulating characteristic and dissolution problem of sulfur and lithium polysulfides. Herein, a mesoporous TiO2@PPy material has been fabricated to act as the chemical immobilizer for sulfur species in Li-S battery. In the structure, PPy layer is covered uniformly on surface of the mesoprous TiO2, forming a core-shell structure. The well-developed mesopores act as the reservoir for sulfur, while the PPy layer improves the conductivity of material and further prevents diffusion of soluble polysulfides. The synthesized TiO2/S@PPy composite delivers an improved rate capability and cycling stability, with an initial discharge specific capacity of 1013.7 mAh g−1 at 0.1 C. In addition, the composite reserves a high capacity of 567.0 mAh g−1 after 300 cycles at 0.5 C, with a decreasing rate of 0.103% per cycle.