Metal-organic framework derived binary-metal oxide/MXene composite as sulfur host for high-performance lithium-sulfur batteries

Abstract

As a promising high-energy chemical power source, lithium-sulfur batteries have attracted extensive attention due to their high theoretical specific capacity (1675 mAh g−1) and high theoretical energy density (2600 Wh kg−1). However, some prominent problems restrict the development of lithium-sulfur batteries, including poor intrinsic conductivity of sulfur, larger volume expansion, and the dissolution of polysulfide. Herein, the porous Zn-Co oxide derived from MOFs (metal-organic framework) coated by highly conductive MXene (ZnCo2O4@Ti3C2) is developed as an efficient sulfur immobilizer for lithium-sulfur batteries (LSBs). Benefitting from the high electronic conductivity of MXene, chemical binding sites of metal oxide for polysulfides, and porous structure for ion transfer, the ZnCo2O4@Ti3C2/S composite demonstrates a balanced high electrochemical performance. A high initial discharge capacity of 1283.9 mAh g−1 with a high initial coulombic efficiency of 98.7% at a low current density of 0.1 C. In addition, this sample exhibits outstanding cycling performance at a high current density of 0.5 C. The results showed that the design strategy of MOFs-derived materials has great potential to promote the development of high-performance LSBs.