Confining Li2S6 catholyte in 3D graphene sponge with ultrahigh total pore volume and oxygen-containing groups for lithium-sulfur batteries

Abstract

A three-dimensional reduced graphene oxide (3D rGO) sponge with an ultra-high specific pore volume of 6.4 cm3g-1 and oxygen-containing (e.g., carboxyl) groups finely tuned was designed, synthesized, and employed as an ideal host of Li2S6 catholyte and related compounds for high-performance lithium-sulfur batteries (LSBs). To the best of our knowledge, the 3D rGO in this work exhibits the highest specific pore volume ever. The interconnected porous structure of 3D rGO can totally confine the lithium polysulfides overcoming the shuttle effect. Also, it can offer an excellent electrical conductivity and electrolyte transportation leading to high charge storage capacity. The as-fabricated LSB provides a high discharge capacity of 1607 mAh g−1 at 0.1C and a high areal capacity of 3.53 mAh cm−2. Even at a high sulfur loading content of 6.6 mg cm−2, high utilization (79.4%) of active materials at the 0.1C and low capacity fading rate of 0.065% per cycle at the 1.0C with 98% coulombic efficiency over 200 cycles are achieved. The 3D rGO sponge could be useful for high-energy battery applications.