Hierarchically porous N-doped C nanofibers comprising TiO2 quantum dots and ZIF-8-derived hollow C nanocages as ultralight interlayer for stable Li–S batteries

Hierarchically porous nanofibers comprising TiO2 quantum dots and metal-organic-framework-derived hollow N-doped C nanocages (HNCs), abbreviated as [email protected]2/HNC NFs, have been introduced as ultra-lightweight multifunctional interlayers for stable Li–S batteries (LSBs). The hierarchically porous and highly conductive N–C nanofiber framework provides numerous conductive channels for rapid ionic/electronic transfer and support fast redox processes in addition to an efficient electrolyte percolation. Further, the presence of well-grafted polar TiO2 quantum dots ensures an efficient trapping and reuse of the lithium polysulfide species thus prohibits their migration toward the Li anode leading to high active-material utilization. Benefitting from these structural merits, the Li–S cells utilizing a high effective sulfur content (∼61 wt%) electrode and [email protected]2/HNC-NF-coated separator exhibits satisfactory rate and cycling performance (590 mA h g−1 after 500 cycles at 0.1C with an average capacity fading of only 0.11%). The combined strategy of developing a porous and highly conductive N–C framework comprising well-embedded polar TiO2 quantum dots reported in this work will provide valuable insights to the synthesis of advanced functional interlayers suitable for applications in various energy storage systems.