Optimization of Dual-Salt Electrolytes for Rechargeable Lithium Metal Batteries

Abstract

Rechargeable Li metal batteries have been extensively studied over the past 40 years due to an increasing need for high energy batteries. Lithium metal is an ideal anode material for rechargeable batteries, because of its extremely high theoretical specific capacity (3,860 mAh g-1), the lowest negative electrochemical potential (-3.040 V vs. the standard hydrogen electrode) and a low gravimetric density (0.534 g cm-3). However, there are still tremendous challenges hampering its practical applications owing to many issues, such as Li dendrite growth and low Coulombic efficiency during charge/discharge processes are key problems that need be solved. Uncontrollable dendritic Li growth and limited Coulombic efficiency could lead to short cycling life and safety hazards because of potential internal short circuits. In this work, we will demonstrate a variety of strategies for Li anode protection to improve its Coulombic efficiency and extend the cycling lifespan in traditional Li-ion battery electrolytes. The highly-efficient electrolyte compositions for Li metal batteries will be developed, optimized and evaluated, and especially the dual salt electrolyte system will be thoroughly investigated to dig out a deep understanding of the relationship between electrolyte recipe, solid-electrolyte interphase (SEI) and cell performance. Also, the solvent effect on the stable cycling of Li anode will be explored and discussed. The optimized electrolyte will be evaluated in the Li||LiNi1/3Mn1/3Co1/3O2 (NMC) coin cells with an NMC areal loading of 2.8 mAh cm-2. In addition, the temperature effect on the electrolyte stability in the cells will be studied. Details of the studies will be reported and discussed in the presentation.