Double-Shelled Phosphorus and Nitrogen Codoped Carbon Nanospheres as Efficient Polysulfide Mediator for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur batteries are regarded as very promising energy storage devices due to their high energy density, low cost, and environmental friendliness; however, their insulating properties and the instability of sulfur-based electrodes impede the practical applications of Li-S batteries. Here, a versatile strategy to synthesize double-shelled nitrogen and phosphorus codoped carbon spheres (NPDSCS) as an efficient sulfur host for Li-S batteries is reported. With strong trapping, good affinity, high adsorption for polysulfides, and the bifunctional catalyzing for sulfur redox processes, the developed NPDSCS cathodes with a high S loading of 72.4% exhibit large specific discharge capacity of 1326 mAh g-1 at 0.1C, high Coulombic efficiency, good rate capability, and excellent cycling performance with a reversible capacity of 814 mAh g-1 at 1C after 500 cycles.