Selenium-embedded hierarchical porous carbon nanofibers toward stable potassium storage

Porous carbon fiber substrates play a pivotal role in enhancing the performance of potassium-selenium (K-Se) battery, as they are key to efficiently confining small Se molecules and regulating selenide reactions. Herein, to address the issues of volumetric expansion and polyselenide formation caused by disordered Se aggregation, a three-dimensional composite material of microporous carbon nanofibers coated with Se and Fe was synthesized, effectively suppressing the shuttle effect of liquid-phase polyselenides. State-of-the-art analytical techniques and theoretical modeling were employed to elucidate the deposition dynamics of Se molecules within micropores and the mitigation mechanisms for volumetric expansion effects. The pore-confinement effect optimizes the spatial distribution of Se, while Fe catalyzed the K₂Se_x, effectively mitigating the sluggish reaction kinetics associated with K₂Se_x formation. This study offers a theoretical framework and experimental insights to advance the development of K-Se battery with high energy density and superior cycling stability.