MOF-derived NiO–NiCo2O4@PPy hollow polyhedron as a sulfur immobilizer for lithium–sulfur batteries

Abstract

The lithium–sulfur battery has been regarded as a highly competitive candidate for the efficient energy storage devices owing to its high theoretical capacity (1675 mA h g⁻¹) and energy density (2600 W h kg⁻¹). Herein, we have designed and synthesized a unique metal–organic framework (MOF)-derived NiO–NiCo₂O₄@PPy hollow polyhedral structure material as an efficient sulfur immobilizer for lithium–sulfur batteries (LSBs). The NiO–NiCo₂O₄@PPy structure effectively alleviates volume expansion, increases electronic conductivity, and enhances the binding effect on lithium polysulfides by chemical fixation. The S/NiO–NiCo₂O₄@PPy composite displays a high initial discharge capacity of 963 mA h g⁻¹ with a high initial coulombic efficiency of 95.2% at a low current density of 0.2C. In addition, this sample exhibits good cycling performance at a high current density of 1C. All the results show that this design strategy has great potential to promote the design of MOF-derived materials for LSBs.