title: A Highly Reversible Room-Temperature Sodium Metal Anode.
abstract: Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating-stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved over 300 plating-stripping cycles at 0.5 mA cm(-2). The long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium-sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies.
authors.affiliation: Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Zhi Wei
authors.initials: ZW
authors.lastname: Seh
authors.affiliation: Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Yongming
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States; Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui