TiO₂ coated three-dimensional hierarchically ordered porous sulfur electrode for the lithium/sulfur rechargeable batteries

Abstract

A three-dimensional (3D) hierarchically ordered mesoporous carbon–sulfur composite slice coated with a thin TiO2 layer has been synthesized by a low-cost process and investigated as a cathode for the lithium–sulfur batteries. The TiO2 coated carbon sulfur composite thin slice works as a binder-free cathode without any current collectors for lithium–sulfur batteries. The hierarchical architecture provides a 3D conductive network for electron transfer, open channels for ion diffusion and strong confinement of soluble polysulfides. Meanwhile, TiO2 (titanium dioxide) coating layer could further effectively prevent the dissolution of polysulfides and also improve the strength of the entire electrode, thereby enhancing the electrochemical performance. As a result, after TiO2 coating, the electrode demonstrates excellent cycling performance, with a discharge capacity of 608 mAh/g at 0.2 C current rate and 500 mAh/g at 1 C current rate after 120 cycles, respectively.