Typically, it is assumed that defects formed at high synthesis/formation temperatures (T formation ) are "frozen in" due to the large kinetic barriers at lower temperatures that prevent their re-equilibration. However, the SEI between Li and LiPON forms spontaneously at temperatures lower than 100 C. As such, we expect defect formation in the SEI components at these lower temperatures. Therefore, for all the SEI components in this study, we consider that the defects are "frozen in" in the T formation range of 300-500 K, which is from room temperature to higher temperatures that might be reached due to the exothermic nature of the LiPON decomposition reactions. Under the most Li-rich (reducing) condition (Figure ), E Fermi,eq is at 5.05 eV (300 K) and 5.04 eV (500 K). Note that the decrease of E Fermi, eq from 300 K to 500 K is within 6 meV, which is indiscernible in the figure, so the vertical dashed line is representative of E Fermi, eq throughout the temperature range of interest. At E Fermi,eq , the dominant defects are