Three-dimensionally ordered macro/mesoporous TiO2 matrix to immobilize sulfur for high performance lithium/sulfur batteries.

A three-dimensionally (3D) ordered macro-/mesoporous TiO2 (3DOM-mTiO2) was synthesized via a simple solvothermal process. 3DOM-mTiO2 was used as a sulfur carrier for cathode materials in a lithium-sulfur (Li-S) battery. The orderly interconnected macro and mesopores structure within the macropore walls yield a large pore volume and high specific surface area in 3DOM-mTiO2, which improved the sulfur loading capacity of the material. The S/TiO2 composite was synthesized as a cathode material for lithium/sulfur battery, which initially produced a high capacity of 1089 mAh g-1 and retained a value of 703 mAh g-1 after 200 cycles. An initial current rate of 0.2 C was used, which was further increased up to 2.5 C when a reversible capacity of 651 mAh g-1 was obtained. The excellent electrochemical performance can be attributed to the 3D ordered macro-/mesoporous structure of TiO2, which physically confines the soluble lithium polysulfides and diminishes the sulfur volume expansion upon cycling. In addition, the strong electrostatic attraction between the Ti-O bond and polysulfide stimulates the performance via stronger adsorption of the electrochemical reaction products.