Electronic Modulation and Symmetry‐Breaking Engineering of Single‐Atom Catalysts Driving Long‐Cycling Li‐S Battery

Developing efficient and durable single‐atom catalysts is vitally important for the sulfur redox reaction (SROR) in Li‐S battery, while it remains enormous challenging. Herein, undercoordinated Ni‐N3 moieties anchored on N,S‐codoped porous carbon (Ni‐NSC) is obtained to enhance the SROR. The experiments and theoretical calculations indicate that the symmetry‐breaking charge transfer in Ni single‐atom catalyst originates from tuning effect of sulfur atoms mediated Ni‐N3 moieties, which can both facilitate the chemical adsorption by formation of N‐Ni⋯Sn2‐, and achieve a rapid redox conversion of polysulfides because of the enhanced electron transfer. As results, the Ni‐NSC based Li‐S battery delivers a very high initial reversible capacity (1025 mAh g‐1 at 1 C), as well as outstanding cycling‐stability for 2400 cycles at 2 C and 3 C, respectively. Noteworthy, the areal capacity can reach 7.8 mAh cm‐2 at 0.05 C and a retention capacity of 4.7 mAh cm‐2 after 100 cycles at 0.2 C for Ni‐NSC based Li‐S battery with sulfur loading of 5.88 mg cm‐2. This work provides profound insight for rational optimizing microscopic electronic density of active site to promoting SROR in metal‐sulfur batteries.