Bimetallic Selenide Decorated Nanoreactor Synergizing Confinement and Electrocatalysis of Se Species for 3D-Printed High-Loading K-Se Batteries.

The potassium-selenium (K-Se) battery has been considered an appealing candidate for next-generation energy storage systems owing to the high energy and low cost. Nonetheless, its development is plagued by the tremendous volume expansion and sluggish reaction kinetics of the Se cathode. Moreover, implementing favorable areal capacity and longevous cycling of a high-loading K-Se battery remains a daunting challenge facing commercial applications. Herein, we devise a Se and CoNiSe coembedded nanoreactor (Se/CoNiSe-NR) affording low carbon content as an advanced cathode for K-Se batteries. We systematically uncover the enhanced KSe/KSe adsorption and promoted K diffusion behavior with the incorporation of Co throughout theoretical simulation and electrokinetic analysis. As a result, Se/CoNiSe-NR harvests high cycling stability with a capacity decay rate of 0.038% per cycle over 950 cycles at 1.0 C. More encouragingly, equipped with a 3D-printed Se/CoNiSe-NR electrode with tunable Se loadings, K-Se full batteries enable steady cycling at an elevated Se loading of 3.8 mg cm. Our endeavor ameliorates the capacity and lifetime performance of the emerging K-Se device, thereby offering a meaningful tactic in pursuing its practical application.