Lithium superoxide encapsulated in a benzoquinone anion matrix.

ABSTRACT: Lithium peroxide is the crucial storage material in lithium-air batteries. Understanding the redox properties of this salt is paramount toward improving the performance of this class of batteries. Lithium peroxide, upon exposure to p-benzoquinone (p-C₆H₄O₂) vapor, develops a deep blue color. This blue powder can be formally described as [Li₂O₂][Formula: see text] [LiO₂][Formula: see text] {Li[p-C₆H₄O₂]}0.7, though spectroscopic characterization indicates a more nuanced structural speciation. Infrared, Raman, electron paramagnetic resonance, diffuse-reflectance ultraviolet-visible and X-ray absorption spectroscopy reveal that the lithium salt of the benzoquinone radical anion forms on the surface of the lithium peroxide, indicating the occurrence of electron and lithium ion transfer in the solid state. As a result, obligate lithium superoxide is formed and encapsulated in a shell of Li[p-C₆H₄O₂] with a core of Li₂O₂ Lithium superoxide has been proposed as a critical intermediate in the charge/discharge cycle of Li-air batteries, but has yet to be isolated, owing to instability. The results reported herein provide a snapshot of lithium peroxide/superoxide chemistry in the solid state with redox mediation.

SUBMITTER: Nava M 

PROVIDER: S-EPMC8713792 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature