Ultrahigh Volumetric Capacity Enabled by Dynamic Evolutions of Host-Guest Pairs in Self-Supporting Lithium-Sulfur Batteries

Conductive porous carbons are promising sulfur host materials for improving mass and areal capacities in lithium-sulfur (Li–S) batteries, but they face a few congenital deficiencies, such as low tap density and weak entrapment ability toward lithium polysulfides (LiPS), resulting in poor volumetric performance. Herein, we report a self-supporting cathode based on electrochemical active graphene-like RuO2 (GRO) without the incorporation of any carbon hosts and additives to synchronously acquire high mass, areal and volumetric capacities. It has been certified that dynamic evolutions of both conductive GRO host and sulfur guest during cell operation expedite chemisorption/conversion of LiPS and regulate nucleation/growth of solid Li2S, which enables GRO-S with medium sulfur loading to achieve an almost theoretical capacity at 0.2 C. Remarkably, the electrode with higher sulfur loading of 8.4 mg cm−2 delivers mass, areal and volumetric capacities of 1225 mAh g−1, 10.3 mAh cm−2 and 1981 mAh cm−3 at 0.2 C, respectively. The volumetric capacity records the highest value in reported Li–S batteries. The cathode material reported in this work opens new avenues for the development of high-energy-density and long-life Li–S batteries.