Physical Investigation of the Mechanisms of Lithium Insertion in Sulfides as Anode Materials for Lithium-Ion Batteries

Electrochemical and chemical lithium insertion (via n-butyllithium) were carried out on a family of spinel phases of the Cu2S-In2S3-SnS2 system. Electrochemical measurements have revealed great reversible capacities and the possible use of these materials as negative electrodes in lithium-ion batteries, Sn-119 Mossbauer spectroscopy, Li-7 NMR and S K edge EXAFS spectroscopy were carried out to characterize the mechanisms of lithium insertion. This study has shown the formation of lithium-metal alloys finely dispersed in an amorphous lithium sulfide matrix at low potentials. A model is proposed to explain the great capacities observed in these materials.