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

TL;DR

This paper introduces a novel lithium salt, LiPFBS, that stabilizes ether-based electrolytes at high voltages, enabling high-voltage lithium metal batteries with improved stability and performance.

Contribution

The study presents a new lithium salt, LiPFBS, that enhances electrolyte stability and interphase formation, allowing high-voltage operation of lithium metal batteries with ether electrolytes.

Findings

LiPFBS stabilizes DME electrolyte at 4.6 V.

PFBS-derived CEI layer improves high-voltage performance.

Enhanced durability of lithium metal batteries under high voltage.

Abstract

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 perfluorobutane sulfonate (LiPFBS) / dimethoxyethane (DME) electrolyte to stabilize DME in a 4.6 V Li-Li LCO battery. Our study focuses on the formation of solid-electrolyte interphase (SEI) and cathode-electrolyte interphase (CEI) layers compared to 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.