A PAN/ZIF-67-derived Co/N-doped carbon nanofiber interlayer for lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries offer a high theoretical energy density, yet their practical deployment is hampered by polysulfide shuttling, insulating active materials, and sluggish Li2S nucleation–dissociation kinetics. Here, we report a freestanding Co/N co-doped carbon nanofiber interlayer (Co-CNF), produced by one-step carbonization of an electrospun PAN/ZIF-67 mat and inserted between the sulfur cathode and the separator. The interlayer introduces a continuous, electronically conductive fiber network that extends the cathode/electrolyte reaction interface from a two-dimensional boundary into a three-dimensional architecture, while the embedded cobalt and nitrogen sites chemically anchor polysulfides and facilitate polysulfide conversion. Cells incorporating the Co-CNF interlayer deliver 88.5% sulfur utilization at 0.1 A g−1 and a low capacity-decay rate of 0.086% per cycle over 250 cycles at 0.5 A g−1, and the lithium anode remains smooth and compact after cycling. The streamlined PAN/ZIF-67 electrospinning-carbonization route therefore offers a simple and potentially scalable pathway to functional interlayers for Li–S batteries.