Topological Insulator Heterojunction with Electric Dipole Domain to Boost Polysulfide Conversion in Lithium-Sulfur Batteries

The heterojunction materials are considered as promising electrocatalyst candidates that empower advanced lithium-sulfur (Li-S) batteries. However, the detailed functional mechanism of heterojunction materials to boost the sulfur redox reaction kinetics remains unclear. Herein, we construct a multifunctional potential well-type Bi2Te3/TiO2 topological insulator (TI) heterojunction with electric dipole domain to elucidate the synergistic mechanism, which facilitates rapid mass transport, strengthens polysulfide capture ability and accelerates polysulfide conversion. Therefore, the Li-S battery with Bi2Te3/TiO2 TI heterojunction modified separator achieves high utilization of sulfur cathode, delivering a high reversible specific capacity of 1375 mAh g-1 at 0.2 C and long cycling capability with a negligible capacity decay of 0.022% per cycle over 1000 cycles at 1 C. Even with the high sulfur loading of 13.2 mg cm-2 and low E/S ratio of 3.8 µL mg-1, a high area capacity of 11.2 mAh cm-2 and acceptable cycling stability can be obtained. This work provides guidance for designing high-efficiency TI heterojunctions to promote the practical application of Li-S batteries.