In‐Situ Synthesis of Carbon‐Encapsulated Atomic Cobalt as Highly Efficient Polysulfide Electrocatalysts for Highly Stable Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries have been considered as one of the most promising electrochemical energy storage systems because of their high energy density. However, a series of issues severely limit the practical performances of Li–S batteries such as low conductivity, significant volume change, and shuttle effect. The hollow carbon spheres with huge voids and high electrical conductivity are promising as sulfur hosts. Unfortunately, the nonpolar nature of carbon materials cannot prevent the shuttle effect effectively. In this case, the atomic cobalt is introduced to a nitrogen‐doped hollow carbon sphere (ACo@HCS) through polymerization and controlled pyrolysis. The atomic cobalt dopants not only act as active sites to restrict the shuttle effect, but also can promote the kinetics of the sulfur redox reactions. ACo@HCS acting as sulfur host exhibits a high discharge capacity (1003 mAh g−1) at a 1.0 C rate after 500 cycles, and the corresponding decay rate is as low as 0.002% per cycle. This exciting work paves a new way to design high‐performance Li–S batteries. The atomic metal cobalt can effectively improve the reaction kinetics of Li–S batteries. Experimental and DFT calculation results show that the discharging process on the Co‐N‐C surface is “easier” than that on the graphite (002) surface. Co–N–C can greatly decrease the reduction barrier of LPSs, facilitate the decomposition of Li2S and enhance the reaction reversibility.