Comparative study of electrochemical properties of SnS and SnS2 as anode materials in lithium-ion batteries

Phase pure SnS and SnS2 were synthesized via the precipitation reaction and investigated as active anode materials for lithium-ion batteries. The crystal structure, morphology and chemical composition of the as-synthesized materials were determined by various physio-chemical techniques such as powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties of the SnS and SnS2 active anode materials were investigated by galvanostatic cycling with potential limitation, cyclic voltammetry, electrochemical impedance spectroscopy and electrochemical in-situ dilatometry. It was shown that the SnS2 electrodes exhibit superior cycling performance properties compared to the SnS electrodes. This is due to the higher amount of Li2S which is produced during the conversion reaction of SnS2 as well as to the intercalation of Li into the SnS2 crystal structure prior to conversion, which allows for a finer distribution of Li2S within the electroactive material.