Lithium insertion in copper, indium, tin thiospinels characterized by Sn-119 Mossbauer spectroscopy and Rietveld analysis

Chemical lithium insertion via n-butyllithium was carried out on a family o f spinel phases of the Cu2S-In2S3-SnS2 system, of general formula Cu0.5+alp haIn2.5-3 alphaSn2 alphaS4, 0 less than or equal to alpha less than or equa l to 0.5. Structural analyses were performed by X-ray and neutron powder di ffraction (Rietveld method) and Sn-119 Mossbauer spectroscopy. Two mechanis ms of lithium insertion occur at the same time. The first is characterized by the reduction of Sn-IV into Sn-II and a spinel to rocksalt transformatio n. The second leads to the total reduction of tin cations into Sn-0 and the formation of metallic bonds in an amorphous phase. The relative amounts of indium and tin are discussed with respect to the crystallinity of the rock salt phase. An electrochemical study was carried out to evaluate the cyclin g behavior of these compounds, and their possible use as anode material in lithium ion cells.