Toward Complete Transformation of Sodium Polysulfides by Regulating the Second‐Shell Coordinating Environment of Atomically Dispersed Fe
Ruilin Bai, Qiaosong Lin, Xinyu Li, Fangxin Ling, Huijuan Wang, Sha Tan, Lingxiang Hu, Mingze Ma, Xiaojun Wu, Yu Shao, Xianhong Rui, Enyuan Hu, Yu Yao, Yan Yu
Abstract
Abstract Room temperature sodium‐sulfur (RT Na‐S) batteries are highly competitive as potential energy storage devices. Nevertheless, their actually achieved reversible capacities are far below the theoretical value due to incomplete transformation of polysulfides. Herein, atomically dispersed Fe‐N/S active center by regulating the second‐shell coordinating environment of Fe single atom is proposed. The Fe−N 4 S 2 coordination structure with enhanced local electronic concentration around the Fermi level is revealed via synchrotron radiation X‐ray absorption spectroscopy (XAS) and theoretical calculations, which can not only significantly promote the transformation kinetics of polysulfides, but induce uniform Na deposition for dendrite‐free Na anode. As a result, the obtained S cathode delivers a high initial reversible capacity of 1590 mAh g −1 , nearly the theoretical value. This work opens up a new avenue to facilitate the complete transformation of polysulfides for RT Na‐S batteries.