A rational design of titanium-based heterostructures as electrocatalyst for boosted conversion kinetics of polysulfides in Li-S batteries.

Lithium-sulfur batteries have great potential for next-generation electrochemical storage systems owing to their high theoretical specific energy and cost-effectiveness. However, the shuttle effect of soluble polysulfides and sluggish multi-electron sulfur redox reactions has severely impeded the implementation of lithium-sulfur batteries. Herein, we prepared a new type of TiC-TiO heterostructure sandwich nanosheet confined within polydopamine derived N-doped porous carbon. The highly polar heterostructures sandwich nanosheet with a high specific surface area can strongly absorb polysulfides, restraining their outward diffusion into the electrolyte. Abundant boundary defects constructed by new types of heterostructures reduce the overpotential of nucleation and improve the nucleation/conversion redox kinetics of LiS. The TiC-TiO@NC/S cathode exhibited discharge capacities of 1363, and 801 mAh g at the first and 100th cycles at 0.5C, respectively, and retained an ultralow capacity fade rate of 0.076% per cycle over 500cycles at 1.0C. This study provides a potential avenue for constructing heterostructure materials for electrochemical energy storage and catalysis.