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 LiO, the impact of nanopore size on the LiO 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 LiO with a thickness of 2-5 nm is formed, possibly via a surface-driven mechanism. When the nanochannel becomes larger, the LiO film thickness saturates at ca. 10 nm, along with crystalline LiO particles possibly formed by a solution-mediated mechanism.