Cathode Chemistries of Lithium-Oxygen Batteries in Nanoconfined Space

In lithium-oxygen batteries, although the porous carbon cathodes are widely utilized to tailor the properties of discharged Li₂O₂, the impact of nanopore size on the Li₂O₂ formation and decomposition reactions remain incompletely understood. Here, we provide the straightforward elucidation on the effect of pore size in a range of 25-200 nm, using a highly ordered porous cathode matrix based on the carbon-coated anodic aluminum oxide membrane formed on an Al substrate (C/AAO_Al). When the nanopore size is 25 nm, film-like Li₂O₂ with a thickness of 2-5 nm is formed, possibly via a surface-driven mechanism. When the nanochannel becomes larger, the Li₂O₂ film thickness saturates at ca. 10 nm, along with crystalline Li₂O₂ particles possibly formed by a solution-mediated mechanism.