From the diffraction data, it appears that at 3 Li/(Sb+Bi), a single phase fcc material is thermodynamically favored for the full compositional range, although for x = 0.50, an annealing step was necessary. It is important to consider whether this behavior would be representative of Li3Sb2 and Li2Sb) are formed and that Li3Sb immediately forms instead. However, this claim contradicts the findings from in-situ XRD by Hewitt et al., where Li2Sb was observed. Operando NMR measurements have also confirmed the formation of Li2Sb during lithiation. When we attempted to synthesize pure Li2Sb by ball milling, the as-milled powder consisted of Sb metal, cubic Li3Sb, and only a trace amount of Li2Sb (see Figure ). Incidentally, we observed that this phenomenon is not confined to the Li-Sb system Li15Si4 is formed when a Li-Si mixture is milled as well, as per Figure . Directly contacting Li metal and Sb is equivalent to short-circuiting a half-cell battery and setting the working electrode potential to 0 V vs. Li. As a result, the most concentrated lithiated phase is formed first and Li2Sb is obtained only after annealing, as shown in Figure and Figure . When the SbxBi1-x solid solutions are being milled with Li metal, the powder mixtures most likely consist of Li metal, SbxBi1-x solid solution, and Li3SbxBi1-x, where Li and SbxBi1-x directly react to Li3SbxBi1-x without forming any intermediate phases, which is different from the reaction mechanism during electrochemical cycling observed by Hewitt et al., but similar to that observed by Darwiche et al. At present, however, no in-situ or operando diffraction studies exist for these ternary compounds.