Highly active CoP-Co2N confined in nanocarbon enabling efficient electrocatalytic immobilizing-conversion of polysulfide targeting high-rate lithium-sulfur batteries

Lithium-sulfur batteries suffer from poor cycling stability because of the intrinsic shuttling effect of intermediate polysulfides and sluggish reaction kinetics, especially at high rates and high sulfur loading. Herein, we report the construction of a CoP-Co2[email protected] carbon polyhedron uniformly anchored on three-dimensional carbon nanotubes/graphene (CoP-Co2[email protected]/CG) scaffold as a sulfur reservoir to achieve the trapping-diffusion-conversion of polysulfides. Highly active CoP-Co2N shows marvelous catalytic effects by effectively accelerating the reduction of sulfur and the oxidation of Li2S during the discharging and charging process, respectively, while the conductive NC/CG network with massive mesoporous channels ensures fast and continuous long-distance electron/ion transportation. DFT calculations demonstrate that the CoP-Co2N with excellent intrinsic conductivity serves as job-synergistic immobilizing-conversion sites for polysulfides through the formation of P···Li/N···Li and Co···S bonds. As a result, the [email protected]2[email protected]/CG cathode (sulfur content 1.7 mg cm−2) exhibits a high capacity of 988 mAh g−1 at 2 C after 500 cycles, which is superior to most of the electrochemical performance reported. Even under high sulfur content (4.3 mg cm−2), it also shows excellent cyclability with high capacity at 1 C.