Highly Antioxidative Lithium Salt Enables High-Voltage Ether Electrolyte for Lithium Metal Battery

Ether-based electrolytes exhibit excellent compatibility with Li metal anodes, but their instability at high voltages limits their use in high-voltage Li metal batteries. To address this issue, we introduce an alternative perfluorobutanesulfonate (LiPFBS)/dimethoxyethane (DME) electrolyte to stabilize DME in a 4.6 V Li∥LCO battery. Our study focuses on the formation of solid-electrolyte interphase (SEI) and cathode-electrolyte interphase (CEI) layers compared with the LiTFSI/DME electrolyte. We demonstrate that LiPFBS helps maintain DME’s compatibility in SEI formation. Additionally, a durable CEI layer derived from PFBS^- enhances the performance of the cell at high voltages by forming a robust, inorganic-dominant CEI layer. A PFBS^--derived CEI significantly enhances the overall performance of the full cell under high voltage conditions.