High rate and stable cycling of lithium metal anode

TLDR

Lithium metal is an ideal battery anode, but dendrite growth and low Coulombic efficiency hinder its practical use. The study aims to develop a highly concentrated electrolyte that enables high‑rate cycling of lithium metal anodes. The improved performance arises from increased solvent coordination and higher lithium ion concentration in the electrolyte. Using 4 M LiFSI in 1,2‑dimethoxyethane, a Li|Li cell cycled at 10 mA cm⁻² for over 6,000 cycles and a Cu|Li cell at 4 mA cm⁻² for over 1,000 cycles with average Coulombic efficiencies up to 99.1 % and 98.4 % respectively, without dendrite growth.

Abstract

Abstract Lithium metal is an ideal battery anode. However, dendrite growth and limited Coulombic efficiency during cycling have prevented its practical application in rechargeable batteries. Herein, we report that the use of highly concentrated electrolytes composed of ether solvents and the lithium bis(fluorosulfonyl)imide salt enables the high-rate cycling of a lithium metal anode at high Coulombic efficiency (up to 99.1%) without dendrite growth. With 4 M lithium bis(fluorosulfonyl)imide in 1,2-dimethoxyethane as the electrolyte, a lithium|lithium cell can be cycled at 10 mA cm −2 for more than 6,000 cycles, and a copper|lithium cell can be cycled at 4 mA cm −2 for more than 1,000 cycles with an average Coulombic efficiency of 98.4%. These excellent performances can be attributed to the increased solvent coordination and increased availability of lithium ion concentration in the electrolyte. Further development of this electrolyte may enable practical applications for lithium metal anode in rechargeable batteries.