DABCOnium: An Efficient and High‐voltage Stable Singlet Oxygen Quencher for Metal‐O2 Cells

Singlet oxygen ( ¹ O ₂ ) causes a major fraction of the parasitic chemistry during the cycling of non-aqueous alkali metal-O ₂ 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 O ₂ 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–O ₂ batteries and greatly reduces ¹ O ₂ related parasitic chemistry as demonstrated for the Li–O ₂ cell.