Ultrathin Two-Dimensional ordered porous carbon host with atomically dispersed electrocatalytic sites toward high volumetric energy Lithium-Sulfur battery

Despite multimodal approaches to increase the gravimetric capacity of lithium-sulfur (Li-S) batteries over the years, strategies on achieving high volumetric capacity (Qv) at close to practical cell operating conditions with high areal sulfur loading and low electrolyte-to-sulfur (E/S) ratio are still lacking. Here, we report that a synergistic effect of a carbonaceous framework with precisely-controlled porous structure/dimension and highly-active, surface-mediated electrocatalysis by a ruthenium (Ru) single-atom electrocatalyst (SAC) composed of N2RuCl2 achieves high Qv in Li-S batteries. Two-dimensional (2D) and hierarchically ordered porous structures of polymer interfacial self-assembly derived N-doped carbon nanosheets (NCNS) realize a highly-packed sulfur cathode with outstanding Li+ ion diffusivity and electrode stability, which have been considered as main impediments to achieving high Qv in a dense sulfur cathode. Moreover, homogeneous incorporation of N2RuCl2 SAC which has novel Ru coordination environment with two N and Cl atoms on the surface of NCNS remarkably accelerated the reaction kinetics of Li-S electrochemistry and achieved high Qv even at high sulfur loading (5.0 mg cm−2), extremely low E/S ratio (4.5μL mg−1), and low electrode porosity (50 %).