lithiumsulfur

Lithium sulfide and lithium-sulfur collectively refer to compounds and systems that involve lithium and sulfur. In chemistry, lithium sulfide (Li2S) is a binary lithium-sulfur compound. In energy storage, lithium-sulfur battery technology uses elemental sulfur as the cathode and lithium metal as the anode, with lithium salts in an electrolyte. During discharge, sulfur is reduced stepwise to lithium polysulfides and ultimately to Li2S; charging reverses these reactions.

Li2S as a material is an ionic, moisture-sensitive solid. It is typically prepared from lithium precursors and sulfur sources and is used as a precursor or component in sulfur-containing electrodes. Its low electronic conductivity necessitates the use of conductive hosts or additives in practical applications.

Lithium-sulfur batteries are noted for a high theoretical energy density, largely due to the high capacity and low weight of sulfur. Sulfur has a theoretical capacity of about 1675 mAh per gram, and the cell’s theoretical energy density can reach around 2600 Wh/kg when evaluated on the sulfur basis. In practice, cells deliver lower values because of factors such as the poor conductivity of sulfur and Li2S, large volume changes during cycling, and the shuttle effect caused by soluble polysulfides. These challenges can lead to capacity fading and reduced Coulombic efficiency.

Research on Li-S batteries focuses on improving cycle life and safety through conductive carbon hosts, advanced binders, protective interlayers, and electrolyte formulations, including solid or quasi-solid electrolytes to suppress polysulfide dissolution and stabilize the lithium metal anode. Commercial adoption remains developing, with ongoing exploration of high-energy, lightweight configurations for electric vehicles and portable devices.