Surface Functionalization of Mesoporous Silica Enabling Long-Life Lithium-Sulfur Batteries

Abstract

Lithium-sulfur (Li-S) batteries have been regarded as future-generation of energy storage systems due to potential merits of their high energy density and natural abundance of sulfur cathode material. However, their practical applications are significantly limited by poor cycle life, which arises from the highly soluble polysulfide species in the organic electrolyte solution. The dissolved polysulfide ions diffuse toward the lithium anode and are converted to inactive materials on the surface of lithium metal. To tackle this issue, mesoporous material such as ordered mesoporous silica (OMS) has been applied as an additive. However, it is found to be an ineffective polysulfide reservoir, where the cathode undergoes great capacity loss on cycling. In this study, a carbon-coated OMS (c-OMS) is synthesized through selective polymerization on the surface of the mesopores followed by carbonization. The effect of c-OMS additive was examined in coin type cells containing a sulfur composite cathode. The conducting feature of c-OMS is found to effectively enhance the cycling stability of the sulfur cathode.