Besides the stoichiometric ratio of the decomposition products in Eq. 1, the spatial distribution of the SEI components is also expected to a↵ect the overall SEI electronic conductivity. In a previous study,Schwöbel et al. found that the XPS signals indicating the presence of Li 3 N and Li 3 P appear on LiPON surface after short Li vapor exposure, but they then become less intense after longer exposure (> 375 seconds) and finally disappear. The long-exposure case accounts for LiPON being kept in contact with Li metal. The results indicate that Li 3 N and Li 3 P could be absent in close proximity to Li metal and only present near the LiPON side of the SEI. While this analysis is undoubtedly powerful, it is limited in shedding light on the chemical reactivity of Li-metal with LiPON. Such distribution information excludes the highest e we predicted (10 1 10 4 cm 3 ) for Li 3 N and Li 3 P formed under the Li-rich condition. Only the e of Li 3 N and Li 3 P formed under slightly oxidizing conditions are possible in the SEI. Specifically, we consider the moderate condition ( µ Li = 0.39 eV) for Li 3 N as relevant in the SEI, because the Li-poor condition is in equilibrium with N 2 , which is di cult to achieve even upon direct contact with LiPON. For Li 3 P, we consider the Li-poor condition as relevant in the SEI, as it is in equilibrium with LiP, which is realizable in the SEI. For Li 3 N formed under the moderate condition (0.39 V vs. Li/Li + ) and Li 3 P formed under the Li-poor condition, values of e still appear high (10 10 10 3 cm 3 ) and enable electron di↵usion. However, electron conduction can happen only in regions of Resistance (Ω) the SEI where Li 3 N and Li 3 P nucleate. According to the distribution observed in experiments, Li 3 N and Li 3 P cannot form near the Li-metal anode. These evidences suggest that, since Li 3 N and Li 3 P are buried within the SEI layer and far from the Li-metal anode, electrons cannot "percolate" through the SEI, which inhibits further LiPON decomposition. Therefore, this analysis explains the origin of the apparent "kinetic stabilization" of the Li-LiPON interface.