An Entangled Cobalt–Nitrogen–Carbon Nanotube Array Electrode with Synergetic Confinement and Electrocatalysis of Polysulfides for Stable Li–S Batteries

The lithium–sulfur (Li–S) battery is considered as a promising battery chemistry for next-generation energy storage on the merits of low cost and high energy density. However, the sluggish redox kinetics and shuttling effect of lithium polysulfides (LiPSs), especially at high sulfur loading, result in low sulfur utilization, low Coulombic efficiency, and short cycle life. Herein, an entangled N-doped carbon nanotube array with encapsulated Co nanoparticles has been constructed and used as an efficient host for sulfur cathode featuring both physical and chemical trapping ability for soluble LiPSs. Besides, the encapsulated Co nanoparticles combined with N species can accelerate polysulfides redox, which has been proved by electrochemical analysis, in situ spectroscopy, and theoretical calculations. The effective confinement and fast conversion of polysulfides ensure the Li–S battery with a high capacity of 1045 mAh g–1 at 1 C rate and 77.89% capacity retention even after 1000 cycles, and these advantages can even be extended to sulfur loading as high as 15 mg cm–2. More significantly, a pouch cell assembled with the composite sulfur cathode can deliver a stable cycling for more than 150 cycles, further demonstrating the great potential of Li–S batteries for practical applications.