Sodium–oxygen batteries have received a significant amount of research attention as a low-overpotential alternative to lithium–oxygen. However, the critical factors governing the composition and morphology of the discharge products in Na–O₂ cells are not thoroughly understood. Here we show that oxygen containing functional groups at the air electrode surface have a substantial role in the electrochemical reaction mechanisms in Na–O₂ cells. Our results show that the presence of functional groups at the air–electrode surface conducts the growth mechanism of discharge products toward a surface-mediated mechanism, forming a conformal film of products at the electrode surface. In addition, oxygen reduction reaction at hydrophilic surfaces more likely passes through a peroxide pathway, which results in the formation of peroxide-based discharge products. Moreover, in-line X-ray diffraction combined with solid state ²³Na NMR results indicate the instability of discharge products against carbonaceous electrodes. The findings of this study help to explain the inconsistency among various reports on composition and morphology of the discharge products in Na–O₂ cells and allow the precise control over the discharge products.

中文翻译：

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如何控制Na–O ₂电池中的放电产物：空气电极表面上官能团作用的直接证据

钠-氧电池作为锂-氧的低超电势替代品已受到了大量研究关注。然而，控制Na–O ₂电池放电产物的组成和形态的关键因素尚未完全了解。在这里，我们表明，空气电极表面的含氧官能团在Na–O ₂的电化学反应机理中具有重要作用细胞。我们的结果表明，在空气电极表面上存在官能团会使放电产物的生长机制朝表面介导的机制传导，从而在电极表面形成产物的保形膜。另外，亲水性表面上的氧还原反应更可能通过过氧化物途径，这导致形成基于过氧化物的放电产物。此外，在线X射线衍射结合固态²³ Na NMR结果表明放电产物对碳质电极的不稳定性。这项研究的结果有助于解释关于Na–O ₂电池中放电产物的组成和形态的各种报道之间的不一致，并可以对放电产物进行精确控制。