Coordination Engineering Based on Graphitic Carbon Nitrides for Long‐Life and High‐Capacity Lithium‐Sulfur Batteries

Abstract Lithium‐sulfur (Li‐S) batteries have received tremendous academic and industrial attentions owing to their ultrahigh energy density. However, technical challenges including lithium dendrite formation, polysulfide shuttling and sluggish sulfur reaction kinetics limit their cycle life, rate capability and areal capacity, especially at practically high sulfur loadings. Here, coordination‐engineered graphite carbon nitrides is proposed to effectively address these challenges. On the anode a layer of novel N‐rich graphitic carbon nitride (g‐C₃N₅) is applied, in which tricoordinated N atoms display strong affinity to Li⁺, to guide lithium deposition and efficiently inhibit dendrite formation. Besides, a layer of defective g‐C₃N₅ carrying highly active bicoordinated N vacancies and cyano N atoms is applied on the cathode, which significantly adsorb polysulfides and catalyze the reversible conversion, as well as the nucleation and dissolution of Li₂S thereby outcompeting polysulfide shuttling and raising kinetics at high sulfur loading. This coordination‐engineering strategy based on g‐C₃N₅ enables Li‐S batteries exhibiting high stability and low capacity‐fading‐rate (0.03% per cycle) in 400 cycles at the high current rate of 4 C, as well as Li‐S pouch cells showing a high areal capacity of 11.69 mAh cm⁻² at a high sulfur loading of 9.02 mg cm⁻², demonstrating the feasibility of Li‐S batteries in practical applications.