Hierarchically porous TiO2 matrix encapsulated sulfur and polysulfides for high performance lithium/sulfur batteries

A hierarchically porous TiO2 matrix was synthesized via a facile dealloying method for high-performance lithium/sulfur batteries. The dealloying processing forms an interconnected porous structure with high porosity (0.39 cm3 g−1) and large surface area (82.39 m2 g−1). The specific structure provides effective contact between sulfur and host material, thus trapping the polysulfide intermediates and suppressing the shuttle effect. The resulting S/TiO2 composites exhibit excellent cycling and rate performance, which maintained 641 mAh g−1 at 200th cycle at 0.2 C, and 600 mAh g−1 at 2.5 C. The coulombic efficiency remains at nearly 99% except for the first cycle. This excellent electrochemical performance of S/TiO2 composites can be attributed to the strong electrostatic attraction between metal-oxygen bond and polysulfides and structural restriction to encapsulate sulfur of hierarchically porous TiO2.