UC Berkeley

A surfactant material plays a significant role in creating a sulfur/carbon composite for lithium/sulfur cells. CTAB (cetyltrimethylammoniumbromide) is a widely used surfactant material in various fields. In this study we identified the functions of CTAB in a sulfur-graphene oxide composite used as the cathode material for lithium/sulfur cells, and the key features for enhancing the capacity of the cells. The CTAB added in the synthesis procedure reacts with polysulfides during the 155 °C heat treatment and produces cetylamine, cetylmethylamine, cetyldimetylamine, and dimethylpolysulfide as products. Furthermore the composite produced by the reactions between cetyldimetylamine and sulfur cover the surface of the sulfur. These work to enhance the performance of the cells. The findings presented here can be applied to various kinds of sulfur/carbon composites to enhance the performance of the sulfur electrode.