When lithium and sulfur are combined, they react to form a compound known as lithium sulfide. This compound is sometimes also referred to as dilithium sulfide, as it contains two atoms of lithium and one atom of sulfur.
Lithium is one of the most reactive metals, so the compound can easily be prepared by treating it with sulfur. This process is usually done in liquid anhydrous ammonia. Similar to pure lithium, lithium sulfide is also highly reactive. When exposed to air, the compound quickly hydrolyzes to form hydrogen sulfide, a gas with a distinctive rotten egg smell.
Research on the possibility of using lithium sulfide in batteries is important, as it has the potential to generate much more energy than standard lithium-ion batteries.