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

Chemical lithium insertion via n-butyllithium was carried out on a family of spinel phases of the Cu2S-In2S3-SnS2 system, of general formula Cu0.5+alphaIn2.5-3 alphaSn2 alphaS4, 0 less than or equal to alpha less than or equal to 0.5. Structural analyses were performed by X-ray and neutron powder diffraction (Rietveld method) and Sn-119 Mossbauer spectroscopy. Two mechanisms 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 transformation. 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 rocksalt phase. An electrochemical study was carried out to evaluate the cycling behavior of these compounds, and their possible use as anode material in lithium ion cells.