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