Dual-stage polyporate framework with redox mediator for high loading lithium sulfur batteries

Abstract

Realizing a high sulfur loading cathode is a necessary measure for assembling a high actual energy density lithium sulfur battery, which requires consideration of conductivity, reaction interface, confinement of lithium polysulfide, and redox kinetics. Herein, a pomegranate-inspired dual-stage porous graphene foam with large cavity skeletons and submicron small cavity carriers is obtained by combining the bubble-template and the flash-freezing ice-template. Furthermore, the redox mediator of poly (1-aminoanthraquinone) is electropolymerized onto it to obtain a sulfur host with high specific surface area and strong confinement capability. The nanosized sulfur deposition behavior and the rich electronic relay capability of the sulfur host are analyzed by the independent gradient model combined with in-situ Raman spectroscopy. Besides, a few of electro-depolymerization products of poly (1-aminoanthraquinone) are confirmed to be able to migrate to the anode surface to stabilize lithium deposition. With these merits, the assembled lithium sulfur batteries exhibit a discharge capacity of 1214 mAh g−1 and a high capacity retention rate of 75.1 % after 800 cycles at a sulfur loading of 10.0 mg cm−2, and provide an excellent areal capacity of 17.5 mAh cm−2 (867 mAh g−1) even at an ultra-high sulfur loading of 20.1 mg cm−2.