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. Keywords: Lithium-selenium batteries, Se cathode, Alternant layer structure, Syringe-filtration method, Areal capacity