Template‐Sacrificing Synthesis of Asymmetrically Coordinated Zn Single‐Atom Sites for High‐Performance Sodium–Sulfur Batteries
Fangcai Zheng, Fangsheng Chen, Zhiqiang Li, Yao Ge, Shuting Dong, Lingzhi Wei, Qianwang Chen, Changlai Wang, Hui Wang
Abstract
Abstract Metal single‐atom catalysts (SACs) are extensively investigated to accelerate the sulfur redox kinetics in room‐temperature sodium─sulfur (Na─S) batteries. Nevertheless, the influence of the structure symmetry of SACs center on the electrocatalytic mechanism and the precise pathway in which single‐atom active sites facilitate sodium polysulfides (Na 2 S n ) conversion remain unknown. To enable controlled construction of highly active single‐atom configuration, herein, Zn SACs with an asymmetrical Zn─N 3 O configuration are designed for sodium polysulfides conversion. Both theoretical and experimental explorations reveal that the Zn─N 3 O single‐atom center displays higher electrocatalytic activity for polysulfides conversion than the Zn─N 4 single‐atom center. The N/O co‐coordination induces the localized charge at Zn single‐atom center, which strengthens the d‐p hybridization with Na 2 S n and stretches Na─S bond length of Na 2 S n , thus accelerating the sulfur redox reaction kinetics. Consequently, the as‐assembled Na─S batteries achieve a high capacity of 1016 mAh g −1 at 1.0 C with a capacity decay of 0.0186% per cycle over 1000 cycles. This work uncovers the subtle relationship between the electrocatalytic activity of species conversion and the local coordination environment of SACs, and offers a guidance for the design of efficient asymmetrical SACs for different catalysis applications.