Reactivity of Amide Based Solutions in Lithium-Oxygen Cells

The stability of electrolyte solutions during lithium-oxygen cells operation is of great importance and interest. This is because oxides formed during reduction are strong nucleophiles which can initiate solvent decomposition. The highly polar amide based solvents have come to the fore as possible candidates for Li-O-2 applications. They show typical cycling behavior as compared to other solvents; however, their stability toward lithium oxides is shrouded in doubt. The present study has focused on Li-O-2 cells containing electrolyte solutions based on DMA/LiNO3. We have used various analytical tools, to explore the discharge-charge processes and related side reactions. The data obtained from FTIR, NMR, XPS, and EQCM all support a rational decomposition mechanism. The formation of various side products during the course the first discharge, leads to the conclusion that amide based solvents are not suitable for Li-O-2 applications; however, electrolyte solution decomposition reduces the OER overpotential by forming oxidation mediators.