Sol–gel encapsulated lithium polysulfide catholyte and its application in lithium–sulfur batteries

Abstract

Lithium polysulfides are the active cathode species in lithium–sulfur batteries. In this work non-hydrolytic sol–gel chemistry is tuned to create a sol that successfully encapsulates lithium polysulfide solutions, forming a solid polysulfide gel. The chemistry of the polysulfide gel is studied using Fourier transform infrared and Raman spectroscopies, which confirm the presence of active lithium polysulfides. This polysulfide gel is incorporated into a solid state lithium sulfur battery and cycled galvanostatically. Electrochemical impedance spectroscopy confirms that the gel has very similar electrochemical properties to the lithium polysulfide solutions from which it was prepared. Discharge capacities as high as 1 mA h cm⁻² are obtained for a polysulfide gel cathode that is 1 mm thick.