A synthesis method consisting of a mechanical ball milling activation process followed by a sintering heating treatment is proposed to obtain MnSn2 as anode material for Li-ion batteries. This two-step approach strongly reduces the amount of beta Sn impurities and provides a better material morphology. This improves the electrochemical performances, even at high C-rate, as shown from the comparison between electrode materials obtained with and without this preliminary activation process. The electrochemical reactions have been followed at the atomic scale by in situ Sn-119 Mossbauer spectroscopy. The first discharge is a restructuring step that transforms the pristine material into Mn/Li7Sn2 nanocomposite which should be considered as the real starting material for cycling. The delithiation of this nanocomposite is characterized by two plateaus of potential attributed to the de-alloying of Li7Sn2 followed by the back reaction of Mn with poorly lithiated LixSn alloys, respectively. The composition and the stability of the solid electrolyte interphase were characterized by X-ray photoelectron spectroscopy. (C) 2013 Elsevier B.V. All rights reserved.