DABCOnium: An Efficient and High-Voltage Stable Singlet Oxygen Quencher for Metal-O2 Cells.

Singlet oxygen (1 O2 ) causes a major fraction of the parasitic chemistry during the cycling of non-aqueous alkali metal-O2 batteries and also contributes to interfacial reactivity of transition-metal oxide intercalation compounds. We introduce DABCOnium, the mono alkylated form of 1,4-diazabicyclo[2.2.2]octane (DABCO), as an efficient 1 O2 quencher with an unusually high oxidative stability of ca. 4.2 V vs. Li/Li+ . Previous quenchers are strongly Lewis basic amines with too low oxidative stability. DABCOnium is an ionic liquid, non-volatile, highly soluble in the electrolyte, stable against superoxide and peroxide, and compatible with lithium metal. The electrochemical stability covers the required range for metal-O2 batteries and greatly reduces 1 O2 related parasitic chemistry as demonstrated for the Li-O2 cell.