Freestanding layer-structure selenium cathodes with ultrahigh Se loading for high areal capacity Li-Se batteries.

Abstract In this work, a freestanding layer-structure Se cathode, composed of alternant barrier layers and active layers, is synthesized via a facile syringe-filtration strategy. With employing the barrier layers simultaneously acting as polyselenide-interception barriers and as highly conductive current collectors, the active layers with 3D porous architecture are endowed with strong polyselenide-trapping capability and fast redox-conversion capability. Such novel Se cathode readily achieves a high Se loading up to 13.5 mg cm−2. The optimized Se cathode with a high Se loading of 4.5 mg cm−2 exhibits high specific capacity/areal capacity (794 mA h g−1/3.6 mA h cm−2), excellent cycling stability (508 mA h g−1@300 cycles), and remarkable rate capability (389 mA h g−1@800 mA g−1), which is superior to conventional Se cathodes. Graphical abstract A rationally designed freestanding layer-structure Se cathode configuration constructed with alternant active layers and barrier layers has been synthesized via a facile syringe-filtration method. Such freestanding layer-structure Se cathode handily increases Se loading as well as efficiently prevents the polyselenide diffusion, which is highly expected to pave the way for the practical implementation of high energy-density Li-Se batteries. Unlabelled Image Highlights • Freestanding layer-structure Se cathode is prepared by syringe-filtration method. • Freestanding layer-structure Se cathode has a high Se loading up to 13.5 mg cm−2. • Barrier layers play roles in confining polyselenide and reducing cell polarization. • Active layers exhibit enhanced polyselenide-trapping capability. • Freestanding layer-structure Se cathode shows high areal capacity of 3.6 mA h cm−2. [ABSTRACT FROM AUTHOR]