In Situ Imaging Polysulfides Electrochemistry of Li-S Batteries in a Hollow Carbon Nanotubule Wet Electrochemical Cell
Zaifa Wang, Yongfu Tang, Xingjie Fu, Jiawei Wang, Zhangquan Peng, Liqiang Zhang, Jianyu Huang
Abstract
Understanding polysulfide electrochemistry is critical for mitigation of the polysulfide shuttle effect in Li-S batteries. However, in situ imaging polysulfides evolution in Li-S batteries has not been possible. Herein, we constructed a hollow carbon nanotubule (CNT) wet electrochemical cell that permits real-time imaging of polysulfide evolutions in Li-S batteries in a Cs-corrected environmental transmission electron microscope. Upon discharge, sulfur was electrochemically reduced to long-chain polysulfides, which dissolved into the electrolyte instantly and were stabilized by Py14+ cations solvation. Metastable polysulfides prove to be problematic for Li-S batteries, therefore, destabilizing the Py14+-solvated polysulfides by adding low polarized solvents into the electrolyte to weaken the interaction between Py14+ cation and long-chain polysulfides renders a rapid polysulfides-to-Li2S transition, thus efficiently mitigating polysulfide formation and improving the performance of Li-S batteries dramatically. Moreover, the CNT wet electrochemical cell proves to be a universal platform for in situ probing electrochemistry of various batteries.