State of the art Li metal batteries typically rely on ether electrolytes with high salt concentration and/or fluorinated solvents to enable stable cycling. Their high manufacturing costs at scale have motivated us to consider dilute, non-fluorinated ether electrolytes. However, their poor oxidative stability has precluded their application in cells employing transition metal oxide cathodes, which operate at > 4 V vs Li/Li⁺. Herein, we present a possible route forward for the oxidative stabilization of these electrolytes, which enabled the reversible cycling of LiNi_0.8Mn_0.1Co_0.1O₂ at a cutoff of 4.4 V in electrolytes composed only of 1 M salt and 1-2 dimethoxyethane. Through computational and experimental material characterization, it was determined that this behavior was driven by a passivating interphase composed largely of perfluoro alkane species. This work provides a method for the oxidative stabilization of ether electrolytes with a low base materials cost. Figure 1