High-Performance Na-O₂ Batteries Enabled by Oriented NaO₂ Nanowires as Discharge Products

Na-O₂ batteries are emerging rechargeable batteries due to their high theoretical energy density and abundant resources, but they suffer from sluggish kinetics due to the formation of large-size discharge products with cubic or irregular particle shapes. Here, we report the unique growth of discharge products of NaO₂ nanowires inside Na-O₂ batteries that significantly boosts the performance of Na-O₂ batteries. For this purpose, a high-spin Co₃O₄ electrocatalyst was synthesized via the high-temperature oxidation of pure cobalt nanoparticles in an external magnetic field. The discharge products of NaO₂ nanowires are 10-20 nm in diameter and ∼10 μm in length, characteristics that provide facile pathways for electron and ion transfer. With these nanowires, Na-O₂ batteries have surpassed 400 cycles with a fixed capacity of 1000 mA h g^-1, an ultra-low over-potential of ∼60 mV during charging, and near-zero over-potential during discharging. This strategy not only provides a unique way to control the morphology of discharge products to achieve high-performance Na-O₂ batteries but also opens up the opportunity to explore growing nanowires in novel conditions.