Electrolyte Tuning with Low Concentration Additive for Dendrite Suppression in Lithium Metal Anodes

Abstract

Lithium (Li) metal is considered an ideal anode for high energy density storage systems. However, its high reactivity and instability towards organic electrolytes lead to the continuous consumption of electrolytes and Li metal, causing dendrite growth. This induces safety issues, and low cyclability hindering its practical use. Although electrolyte additives are extensively utilized to address these issues, the practice remains an alchemical task with least understanding of their interactions with electrolytic environments. Here, we report a novel electrolyte additive, gadolinium nitrate (Gd(NO3)3) with a low optimal concentration of 3 mM in a Lithium bis(trifluoromethanesulfonyl)imide-Lithium nitrate (LiTFSI-LiNO3) ether-based electrolyte which promotes plating/stripping of Li in nodular morphology, significantly suppressing dendrites and dead Li growth while improving the cycle life, and overall stability of Li metal batteries. A significant reduction of Li-metal electrode overpotential is observed under a current density of 2 mA cm-2. When tested in Li metal battery with LiFePO4 (LFP) cathode at an active mass loading of 4 mg cm-2, capacity retention of 98.33 % is observed at 400 cycles. These stable cycling and enhanced performance are attributed to the formation of a chemically stable, mechanically robust, and ionically conductive solid electrolyte interphase (SEI) layer on the Li metal surface, enabled by the incorporation of Gd(NO3)3 compared to the cells with pristine electrolytes.