The Morphological Effect of Cobalt Oxide Nanocatalysts on the Electrochemical Performance of Lithium-Air Battery

Next generation rechargeable batteries are required to have higher energy density compared to the state-of-art battery. The energy density of the commercial lithium ion battery cannot meet the stringent requirements, whereas the lithium-air battery has high theoretical specific energy coming up to 11700 Wh/kg because lithium–air battery is based on discharge reaction between Li and oxygen to yield Li₂O₂. However, very little is known about the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in the cathode of lithium-air battery. Moreover, lithium oxides like Li₂O and Li₂O₂ are formed in cathode, which are thermodynamically difficult to decompose finally leading to an enormous irreversible reaction. Therefore, many efforts to overcome this problem have focused on finding proper catalysts having significantly improved ORR and OER. As reported previously, because versatile nanomaterials such as nanowires, nanocubes or nanosheet have shown unique chemical or physical properties due to the change of surface area, size confinement effects and etc., their electrochemical properties or catalytic effects were quite different from bulk counterparts when they were applied to various energy devices like fuel cell, lithium ion battery and solar cells. So, we judged that the morphological change of nanomaterial-based catalysts can be one of the main keys for controlling ORR and OER activities of lithium-air battery.

In this study, diverse cobalt oxide-based nanocatalysts in the form of nanocubes and so forth were synthesized, and their catalytic activities were compared in the morphological or structural viewpoint.