Tin oxides as a negative electrode material for Mg-Ion batteries

In this study, SnO as a negative electrode material for Mg-ion batteries exhibits a larger capacity of 540 mA h g-1 at the first cycle than that of pure Sn, despite the lower 88 wt.% Sn content. XRD patterns and XPS spectra reveal alloying/de-alloying, with Sn formed by the reduction during the first charging. The greater capacity is attributed to the shorter Mg diffusion length in the resulting fine Sn particles. The MgO matrix played a role in maintaining the high capacity for more than 10 cycles by diminishing the Sn agglomeration. Graphical Abstract The electrochemical behavior of SnO as a negative electrode material for Mg-ion batteries is described. During the first charge cycle, SnO is reduced to form metallic Sn, which is embedded in amorphous MgO. The fine Sn particles, with a shorter Mg diffusion length, exhibit a reversible capacity of over 500 mA h g-1 through alloying and de-alloying with Mg.