Direct View for the Deformation Evolution of Sulfur Electrode during Li-S Battery Cycling

An experimental set-up was developed which can observe electrode deformation and electrochemical reaction in-situ during the charge-discharge cycling of lithium-sulfur battery. The positive bending deformation during charge and discharge was monitored at real time. It was found that the positive curvature increased during discharge and reduced during open circuit. The curvature would recover the original state during charge period. As electrochemical reaction proceeds, the electrolyte near positive electrode gradually become yellow and deepened due to polysulfide dissolution of discharge products. Results of surface and section morphology observation on sulfur electrode before and after cycle using scanning electron microscope (SEM) were consistent with curvature changes during cycling and verified the volumetric expansion of sulfur electrode.