Co/N-codoped hierarchical porous carbon nanoreactors for catalytic polysulfide conversion in long-cycling potassium–sulfur batteries

Abstract

Potassium–sulfur (K–S) batteries are promising candidates for low-cost and high-energy-density energy storage, but their development is limited by the shuttle effect of soluble potassium polysulfides and sluggish solid–liquid–solid sulfur redox kinetics. Herein, a Co/N-codoped hierarchical porous carbon nanoreactor, denoted as N-PC@dCo, is constructed from a PDA-coated ZnCo-ZIF precursor through controlled carbonization. During pyrolysis, Zn evaporation generates abundant hierarchical pores, the PDA-derived carbon shell strengthens physical confinement and electronic conductivity, and Co/N active sites provide polar adsorption and catalytic centers for potassium polysulfide conversion. Benefiting from the integrated confinement-adsorption-catalysis effect, the N-PC@dCo/S cathode effectively suppresses polysulfide migration, accelerates K2S nucleation/decomposition, and reduces sulfur redox polarization. As a result, the optimized sample delivers a high reversible capacity of 868.2 mAh g−1 after 50 cycles at 0.1 A g−1, and maintains a long cycling stability over 1000 cycles at a high current density of 5 A g−1. Mechanistic studies reveal that the synergistic effect between Co species and N-doping sites effectively accelerates the redox kinetics of polysulfides, thereby significantly suppressing the shuttle effect. This work provides a rational nanoreactor design strategy for regulating potassium polysulfide chemistry toward durable K–S batteries.