Synthesis, Modular Composition, and Electrochemical Properties of Lamellar Iron Sulfides

Transition metal chalcogenides with layered structures have emerged as promising materials for energy storage, catalysis, and electronics, among other areas. We have identified a new layered phase of iron sulfide containing interlayer solvated cations. We present an optimized synthesis for the Li+-containing material from an Fe(III) xanthate complex. Structure and composition data indicate the material consists of poorly-ordered iron sulfide layers separated by solvated cations. The lamellar spacing in these materials can be tuned by changing the identity of the cation. Furthermore, the lamellar spacing can also be reversibly tuned by the degree of solvation of the material. The material is electrically conductive and can serve as a pseudocapacitor with comparable performance to commercial materials such as MnO2. Furthermore, these materials also show promise as lithium or sodium ion battery cathodes with good capacity and reversibility.