Direct Observation of Sulfur Radicals as Reaction Media in Lithium Sulfur Batteries

作者：Wang Qiang^*; Zheng Jianming; Walter Eric; Pan Huilin; Lv Dongping; Zuo Pengjian; Chen Honghao; Deng Z Daniel; Liaw Bor Yann; Yu Xiqian; Yang Xiaoqing; Zhang Ji Guang; Liu Jun; Xiao Jie

来源：Journal of the Electrochemical Society, 2015, 162(3): A474-A478.

DOI：10.1149/2.0851503jes

Lithium sulfur (Li-S) battery has been regaining tremendous interest in recent years because of its attractive attributes such as high gravimetric energy, low cost and environmental benignity. However, it is still not conclusively known how polysulfide ring/chain participates in the whole cycling and whether the discharge and charge processes follow the same pathway. Herein, we demonstrate the direct observation of sulfur radicals by using in situ electron paramagnetic resonance (EPR) technique. Based on the concentration changes of sulfur radicals at different potentials and the electrochemical characteristics of the cell, it is revealed that the chemical and electrochemical reactions in Li-S cell are driving each other to proceed through sulfur radicals, leading to two completely different reaction pathways during discharge and charge. The proposed radical mechanism may provide new perspectives to investigate the interactions between sulfur species and the electrolyte, inspiring novel strategies to develop Li-S battery technology.

• 出版日期2015