Partial occupation of selenium in porous carbon enhances selenium utilization for potassium-ion batteries

Abstract

A “partial occupation” strategy for selenium (Se) cathodes in potassium-ion batteries has been explored in this work, using Zn-HKUST-derived porous carbon as the host. By precisely controlling the Se loading to occupy only the micropores while preserving the mesoporous channels, the Se/C PSC composite effectively mitigates volume expansion and suppresses polyselenide shuttling. Compared with fully occupied Se/C FSC, the partially filled electrode exhibits superior electrochemical performance, which delivers a reversible capacity of 366.5 mA h g⁻¹ after 1000 cycles at 1 A g⁻¹ and retains 113.1 mA h g⁻¹ even at 20 A g⁻¹. These results demonstrate that balancing active material loading with structural stability through pore engineering is crucial for achieving high-rate capability and long-term cycling stability in K–Se batteries.