Electron‐Deficient Cobalt Centers Realized by Rational p─π Conjugation Regulation for High‐Performance Li─S Batteries

Abstract Rational design of the coordination environment of single‐atom catalysts (SACs) can enhance their catalytic activity, which is of great significance for high‐loading and lean‐electrolyte lithium‐sulfur (Li─S) batteries. Inspired by the Lewis acid–base theory, we design a unique coordination environment for constructing electron‐deficient Co SACs on carbon nanotubes (named as CNT@f‐CoNC), which function as a Lewis acid, to enhance the chemisorption and catalytic activity towards polysulfides (Lewis base). Compared with porphyrin‐like Co SACs, electron‐deficient Co SACs (Lewis acid) exhibit much stronger binding affinity towards polysulfides (Lewis base) and a significantly lower energy barrier of the rate‐determining step in the sulfur reduction reaction. As expected, even with a high sulfur loading (6.9 mg cm −2 ) and lean electrolyte to sulfur (E/S) ratio (4.0 µL mg −1 ), the areal capacity still reaches 7.7 mAh cm −2 . Moreover, a 1.6 Ah‐class pouch cell is successfully assembled under the harsh conditions and delivers an energy density of 422 Wh kg −1 . This work provides novel insights into enhancing the electrochemical performance of Li─S batteries by modulating the local electronic density of metal sites through the rational design of the coordination environment.