Mg₂Sn as a New Lithium Storage Intermetallic Compound

Electrochemical Reactivity of Mg2Sn Phases with Metallic Lithium

“…The crystallite sizes calculated for ground samples are similar for all the crystallographic directions, indicating a general isotropy in the crystallite shape. As previously reported, − the proportion of the h-Mg 2 Sn phase increases at the expense of that of c-Mg 2 Sn as the milling time goes on, and it seems therefore difficult to prepare pure c-Mg 2 Sn in that way since both phases are present even after a short milling time. Pure h-Mg 2 Sn is obtained after 65 h of milling, with an iron content of around 0.4 atom % (EDS analysis), indicating a negligible contamination from the vial/ball abrasion.…”

“…This can be investigated through electrode engineering by the use of small particles that could sustain strains with less cracks, the synthesis of composites where metals are embedded in either an active or an inactive matrix, − or the preparation of dense substrated films. − A last approach consisting of designing new powdered multielement alloys that could reversibly react with lithium through a displacement or intercalation process recently revealed very appealing results. Indeed, since the report by Thackeray et al of the insertion of Li into the η-Cu 6 Sn 5 metallic framework, many groups randomly investigated the properties of various binary and even ternary systems. − Among them, the Li−Mg−X systems (X = Si, Ge, Sn, Pb) were recently screened and led to conflicting reports on the reaction proposed to describe the electrochemical lithiation of the structurally alike cubic Mg 2 X phases. − Although the formation of Li 2 MgX phases (Mg 2 X + 2Li → Li 2 MgX + Mg) is a well established and common fact, many questions still remain: the way this ternary phase is formed, its electrochemical activity and stability, the decomposition of the electrodes into Li−X alloys, the formation of Li−Mg phases, the high-voltage behaviors, etc. Among the four Li−Mg−X systems, Li−Mg−Si is the one reaching some kind of consensus, even though the question of the possible formation of Li−Si alloys remains unanswered.…”

“…Among the four Li−Mg−X systems, Li−Mg−Si is the one reaching some kind of consensus, even though the question of the possible formation of Li−Si alloys remains unanswered. In contrast, the reaction of Mg 2 Sn with lithium is far from being totally understood, motivating our choice in this system. ,,

1 X-ray diffraction patterns of the materials obtained by ball-milling Mg/Sn mixtures for milling times ranging from 5 h (a) to 65 h (d), the powder obtained by heating (350 °C/vacuum/5 h) sample d (e), and the sample prepared by heating Mg/Sn mixtures in a sealed quartz tube at 800 °C (f). The h and c labels indicate the Bragg peaks of the high-pressure h-Mg 2 Sn metastable and stable c-Mg 2 Sn phases, respectively.

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Anode Properties of Lithium Storage Alloy Electrodes Prepared by Gas-Deposition

“…Alloys containing elements from 14 family groups are prospective negative-electrode materials for second-generation rechargeable lithium batteries, replacing carbon materials. [1][2][3][4][5][6][7][8][9][10][11][12][13] To date we have focused our research on Mg 2 Ge and found that the charge-discharge capacity of its composing electrodes is higher than that of carbon materials and that its electrochemical reaction is largely based on the reversible absorption and desorption of lithium in the crystal lattice. [14][15][16][17] However, the typical problem of alloy electrodes, namely, low stability of the charge-discharge cycle, exists also for this compound.…”

Corrosion Behavior of an Mg2Sn Alloy

“…The compound has an inverted fluoride crystal structure with Mg occupying the F positions and Sn occupying Ca positions [ 26 ]. A large amount of small-sized Li can be reversibly inserted into the crystal lattice of mechanically alloyed Mg 2 Sn [ 27 ]. Therefore, the material has been studied as lithium storage intermetallic compound.…”