Oxidative Stabilization of Dilute Ether Electrolytes via Anion Modification
John Holoubek, Qizhang Yan, Haodong Liu, Emma Hopkins, Zhaohui Wu, Sicen Yu, Jian Luo, Tod A. Pascal, Zheng Chen, Ping Liu
Abstract
State-of-the-art lithium 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, nonfluorinated 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 LiNi0.8Mn0.1Co0.1O2 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.