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. (paper)