Magnesium hydride as negative electrode active material in lithium cells: A review

MgH2 has been recently proposed in 2008 as novel conversion material for negative electrodes in lithium ion cells (LIC). Since then, many aspects of the electrochemical behaviour in LIC of this material have been investigated: both experimental and computational studies have been carried out to investigate the fundaments of the MgH2 conversion reaction and to demonstrate performances in LIC close to the theoretical predictions (2037 mAh g-1 and 2842 mAh cm-3). The conversion process involves a reversible redox reaction where the pristine binary hydride is electrochemically reduced to magnesium nanoparticles surrounded by a LiH matrix, and oxidized back to MgH2. In recent years the research efforts on this material have been focused on: (a) the identification of successful synthetic routes to achieve good performances in LIC; (b) the understanding of the basics of the MgH2 conversion reaction; (c) the optimization of technological aspects to improve the performances in LIC (e.g. electrode formulation assessment and adoption of solid electrolytes). In this paper we present a comprehensive review about the research studies reported in the literature concerning the use of MgH2 as negative electrode for lithium ion cells.