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 sp(2)-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.