An in-situ catalytic-insoluble strategy enabled by sulfurized polyacrylonitrile-based composite cathode for potassium–sulfur batteries

Abstract

Owing to the insoluble organosulfur mechanism and stable cycling life, sulfurized polyacrylonitrile (SPAN) developed as a promising cathode material for high-energy potassium–sulfur batteries (KSBs). However, it is yet a major challenge to achieve fast catalytic kinetics and high reversible capacity in SPAN-based cathodes. Here, one-step electrospun SPAN nanofibers embedded with Fe[Formula: see text]Nb[Formula: see text]O metal oxide nanoparticles (FeNb@SPAN) have been successfully developed to construct sulfur electrodes with high electrochemical activity, high sulfur utilization, and high cycling stability. The as-prepared freestanding FeNb@SPAN composite cathode, which featuring interwoven nanofibers with Fe[Formula: see text]Nb[Formula: see text]O nanoparticles homogeneously implanted, possesses high storage space for volume expansion and suppresses polysulfide dissolution during potassiation/depotassiation. Benefiting from its unique structure and composition in electrode design, the FeNb@SPAN cathode is endowed with outstanding energy storage performances with a high initial specific capacity of 776 mAh [Formula: see text] g[Formula: see text] under 50 mA [Formula: see text] g[Formula: see text] and an excellent cycling capability of 201 mAh [Formula: see text] g[Formula: see text] after 80 charge/discharge processes. This work heralds a feasible strategy toward SPAN-based sulfur host materials in the structural design of next-generation high-performance cathode materials for KSBs and other metal–sulfur batteries.