Nanoporous NiO Plates with a Unique Role for Promoted Oxidation of Carbonate and Carboxylate Species in the Li-O2 Battery

We report a novel catalytic reaction to promote oxidation of carbonate and carboxylate species using nanoporous nickel oxide (NiO) in the lithium-oxygen (Li-O-2) battery. These nanoporous NiO catalysts in the shape of two-dimensional (2-D) hexagonal plates are incorporated on the carbon nanotube (CNT) electrode, which remarkably enhances oxidation efficiency of carbonate and carboxylate species as representative side products in Li-O-2 electrochemistry and greatly improves the cycleability to more than 70 cycles. The oxidation reaction predominantly occurs at the nanoporous NiO, toward which the carbonate and carboxylate species may migrate for the complete decomposition. This result is notably distinguished from a NiO-free CNT electrode, where such a passivation layer becomes thicker and precludes electron transfer, thus inducing poor cyclability.