Impact of Compression on the Electrochemical Performance of the Sulfur/Carbon Composite Electrode in Lithium-Sulfur Batteries

While lithium-sulfur batteries theoretically have both high gravimetric specific energy and volumetric energy density, only its specific energy has been experimentally demonstrated to surpass that of the state-of-the-art lithium-ion systems at cell level. One major reason for the unrealized energy density is the low capacity density of the highly porous sulfur/carbon composite as the positive electrode. In this work, mechanical compression at elevated temperature is demonstrated to be an effective method to increase the capacity density of the electrode by at least 90 % and moreover extends its cycle life. Distinct impacts of compression on the resistance profiles of electrodes with different thickness are investigated by tortuosity factors derived from both electrochemical impedance spectroscopy, X-ray computed tomography and kinetic analysis based on operando X-ray diffraction. The results highlights the importance of a homogeneous electrode structure highlight lithium-sulfur system.

Automated summary

This study demonstrates that mechanical compression at elevated temperature can effectively increase the capacity density of lithium-sulfur battery electrodes and extend their cycle life. It highlights the importance of a homogeneous electrode structure in the lithium-sulfur system.