Stable Li Metal-Electrolyte Interface Enabled by SEI Improvement and Cation Shield Functionality of the Azamacrocyclic Ligand in Carbonate Electrolytes.

Abstract

To promote the reversible cycleability of Li metal negative electrodes, a Li-chelating azamacrocyclic ligand molecule is introduced into a carbonate-based electrolyte intended for lithium metal batteries. Reversible Li plating and stripping on the Cu electrode are found to be the outcomes of the bifunctional effects of adding the lithium nitrate-chelating azamacrocyclic ligand. The negatively shifted redox potential of the Li-chelating macrocyclic ligand, relative to that of the free Li-ion, acted as a cationic shielding molecule for smooth Li deposition, and the Li3N-based solid electrolyte interphase (SEI) film derived from the nitrate anion strengthened the interphasial characteristics of the Li metal negative electrode. Cationic shielding and Li3N-based SEI composition could help enhance the cycleability of the Li metal in a cascading manner. Consequently, the physicochemical characteristics of the lithium nitrate-chelated 1,4,8,11-tetramethyl-1,4,8,11-tetraazacylcotetradecane molecule exhibit stable Li/LiNi0.8Co0.1Mn0.1O2 cycleability.