(a) Distinct SEIs formed on single crystal Sn electrodes with different surface orientation. (b) sXAS of C-Kedges of the SEIs formed on Sn electrodes with two different surface orientations. sXAS of Li₂CO₃reference is plotted on top for comparison. The distinct SEIs are clearly revealed by the sXAS results of the relevant low-ZelementK-edges, including the C-K, O-K, and F-K.^[54]