Phase separation and amorphisation in lithium inserted Cu–In–Sn sulfospinels: experimental and theoretical approach

119Sn Mössbauer spectroscopy, X-ray diffraction (XRD) and electrochemical experiments were carried out to characterise the reaction mechanism of lithium with spinel phases CuxInySnzS4. The electrochemical investigations have shown interesting reversible capacities for these materials, and their possible use as anode materials in lithium-ion cells. This analysis reveals a multi-phase mechanism linked to the reduction of the cations involving a spinel to rocksalt transformation followed by a structural breakdown. Density functional calculations by the linearised augmented plane wave (LAPW) method give a good interpretation of experimental results for crystalline phases.