One hypothesis for the self-passivation mechanism is that electron transfer is suppressed after the initial SEI formation so that LiPON decomposition is prevented. To confirm this hypothesis, we need to characterize the electronic conductivity of the SEI components. Notably, band gap energy, though often used, is not a reliable descriptor of electronic conductivity. Indeed, it is impossible to establish any empirical relationship between band gap and electronic conductivity for solid electrolytes. Instead, one should assess charged defects as the major source of free charge carriers and the resulting electronic conductivity. Based on defect calculations, our previous study has successfully predicted the electronic conductivity in di↵erent types of solid electrolytes including Li 6 PS 5 Cl and Li 6 PS 5 I argyrodites and Na 3 PS 4 . In this study, we use first-principles defect calculations to predict the electronic conductivity in the Li-LiPON SEI components, Li 2 O, Li 3 N, Li 3 P, and Li 3 PO 4 . We estimate the net free charge carrier concentrations from defect thermodynamics, which are then used with estimated carrier mobilities to determine the electronic conductivity under di↵erent (electro)chemical limits or voltages vs. Li/Li + . In combination with the previous experimental observations of the elemental distributions, we reveal that the SEI electronic self-passivation originates from the insulating nature of the stoichiometrically dominant Li 2 O and uneven distribution of the electronically conductive species Li 3 N and Li 3 P.