In Situ Imaging Polysulfides Electrochemistry of Li‑S Batteries in a Hollow Carbon Nanotubule Wet Electrochemical Cell

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.