To gain deeper insight into the role of added NO3 -, we further introduced LiI into these ether electrolytes with and without NO3 -(Figure ). Adding LiI reduces the oxidation onset potential of pristine ether electrolyte from 3.9 to 2.95 V. As NO3 -and I -anions coexist, the onset potential for I - anions oxidation shifts towards more positive potentials from 2.95 to 3.5 V, confirming competing adsorption between NO3 -and I -anions. Nevertheless, the oxidation onset potential is always less than 3.9 V with the presence of I -, suggesting that the easily oxidized I -anions are more likely to contact the cathode surface and dominate interfacial oxidation. This result re-emphasizes the importance of the adsorbate in the oxidation behavior of the electrolyte. Furthermore, by increasing the concentration of NO3 -in the electrolyte (at fixed main salt concentration of 1 M), the oxidation slowly takes off with its onset potential shifting towards more positive values at higher NO3 -content (Figure ), providing further evidence for competitive adsorption. The detailed mechanisms are illustrated in Figures . These observations are qualitatively consistent with the anion-adsorption mechanism inferred from MD simulations. Additionally, the adsorbability of NO3 -was verified by a steady-state NO3 -anion adsorption experiment without external electrode potential, where a lower NO3 -concentration near the gathered LiCoO2 electrodes can be quantified than in the bulk solution (Note S2 and Figure ). Altogether, our combined experimental and modeling observations unveil the crucial role of NO3 - -adsorbed interfacial structure on the ether reactivity and provide a picture at the molecular level of the NO3 -_ anion adsorption behavior at the electrochemical interfaces: that is, the added nitrate would little change the ion solvation in bulk electrolyte but could significantly regulate the EDL structure to inhibit ether oxidative decomposition at the cathode. Meanwhile, it is worth noting that, unlike in the case of super-concentrated aqueous electrolytes, the interfacial chemical signatures in dilute electrolytes do not inherit from the bulk solution.