Efficient synergism of electrocatalysis and physical confinement leading to durable high-power lithium-sulfur batteries

Lithium-sulfur batteries are facing the big challenge of high-rate charge/discharge with long durability owing to the severe shuttle and polarization effects. Herein, we report a durable high-power cathode for lithium-sulfur batteries by employing multifunctional hierarchical nitrogen-doped carbon nanocages (hNCNC) to encapsulate sulfur and serve as interlayer. The highly-efficient electrocatalytic function of nitrogen-doped sp2-carbon to lithium-polysulfides conversion reactions is revealed by electrocatalytic experiments and density functional theory simulations. The excellent catalytic and charge-transfer functions of hNCNC, together with its physical confinement and chemical adsorption to the polysulfides, effectively suppress the polarization and shuttle effects, leading to the high-power performance with a capacity of 539 mAh g−1 at ultrahigh current density of 20 A g−1 for the sulfur cathode with the areal loading of 0.8 mg cm−2. The superb durability is demonstrated by 1000 cycles at 10 A g−1 with a retained capacity of 438 mAh g−1. When the areal sulfur loading is increased to 3 mg cm−2, a high capacity of 605 mAh g−1 is still obtained at the high current density of 3 A g−1. This study provides an effective approach to durable high-power lithium-sulfur batteries by designing suitable electrocatalytic-active carbon-based hosts.