Highly reversible Li/Li2S3 batteries with an advanced cathode structure

Abstract

In this work, a highly reversible Li/Li₂S₃ cell utilizing a self-weaving, free-standing nitrogen-doped carbon nanotube (NCNT) paper as an electrode is reported. The highly porous structure with a large surface area and the unique Li₂S_x binding capability of the N functional groups make it possible for NCNTs to effectively reserve the polysulfides on the cathode electrode. At the same time, a second “protection net” was constructed in this work through coating nitrogen-doped graphene (NG) on one side of a commercial Celgard polypropylene (PP) separator to further impede the diffusion of polysulfides to the counter electrode. Our designed Li/Li₂S₃ cell can deliver a reversible discharge capacity approaching 1300 mA h g⁻¹ at 0.2C. More interestingly, in a Li-free system using stainless steel as the counter electrode, the Li₂S₃ cathode still delivers 150 mA h g⁻¹ discharge capacity. All the excellent performances suggest a potential route to develop highly reversible and high specific capacity lithium sulfur batteries.