LiFeS2

LiFeS2, also known as lithium iron disulfide, is a chemical compound composed of lithium, iron, and sulfur with the formula LiFeS2. It is one of several lithium-transition metal sulfides that have been investigated for energy storage applications, particularly as a potential electrode material for lithium-based batteries. The material can function as a lithium intercalation or conversion-type electrode, depending on synthesis and operating conditions, with iron that can undergo Fe2+/Fe3+ redox couples during lithiation and delithiation.

Structure and synthesis: LiFeS2 has been reported in multiple crystal structures, including forms related to pyrite-type FeS2 frameworks in which lithium ions occupy interstitial sites or partially substitute for iron. Synthesis is typically achieved by solid-state reaction of Li-containing precursors (such as Li2S) with FeS2 or related sulfide mixtures at elevated temperatures under inert atmosphere; alternative routes include solvothermal methods and mechanical milling. The compound is often sensitive to air and moisture, requiring handling in controlled environments to maintain phase purity.

Properties and applications: In battery research, LiFeS2 has drawn interest as a potential cathode or conversion-type material for lithium batteries. Reported electrochemical performance varies, with challenges including relatively low electronic conductivity, capacity fading, and structural changes during cycling. Research efforts have focused on improving conductivity through carbon coatings or composites, stabilizing the crystal structure, and optimizing synthesis to enhance cyclability and rate capability. It is not widely used in commercial batteries, but remains a subject of academic study for sulfide-based energy storage.

See also: lithium iron phosphate, iron sulfide, pyrite, lithium sulfide.