Partial Occupation of Selenium in Porous Carbon Enhanced Selenium Utilization for Potassium-ion Batteries

Abstract

Here we report a “partial-occupation” concept that precisely loads Se only into the micropores of Zn-HKUST-derived hierarchical carbon (Se/C PSC) while deliberately leaving the mesopores unoccupied. This unique architecture provides dual functions: micropores physically confine small Se chains and suppress polyselenide dissolution, whereas the reserved mesopores act as internal buffers and expressways for K⁺ transport. Se/C PSC delivers a reversible capacity of 366.5 mAh g⁻¹ after 1 000 cycles at 1 A g⁻¹ with only 0.033 % decay per cycle, and retains 113.1 mAh g⁻¹ at an ultrahigh rate of 20 A g⁻¹ performance metrics that substantially exceed those of the fully occupied analogue (Se/C FSC). This work establishes pore-engineering rather than mass-loading maximization as the decisive design principle for high-rate, long-life chalcogen electrodes beyond the K–Se platform.