Aqueous proton batteries (APBs) have attracted much attention owing to their fast kinetics, low cost and sustainability. However, the most reported APBs operate under acidic conditions, which will lead to serious hydrogen evolution reaction (HER) and corrosion problem, inevitably. Here, a small molecule organic compound, azobenzene (AB) containing an azo group (N = N), is explored as an anode material for APBs under alkaline electrolyte with a low redox potential of around -0.6 V (vs. Hg/HgO). AB anode achieves high-rate capacity of 151 mAh g-1 at a high current density of 10 A g-1 and excellent cycling stability over 12,500 cycles under 2 M KOH electrolyte. The experimental results and theoretical calculations confirm that AB performs a two-electron redox reaction involving a central N = N group with two protons from H2O molecules. This work reveals the protonation in azo-materials and promotes new insights on design small organic molecules with multi-electron redox reactions in advanced proton secondary batteries.

中文翻译：

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碱性电解质下的水性质子电池


水系质子电池 （APB） 因其快速动力学、低成本和可持续性而备受关注。然而，报道最多的 APB 在酸性条件下运行，这将不可避免地导致严重的析氢反应 （HER） 和腐蚀问题。在这里，探索了一种含有偶氮基 （N = N） 的小分子有机化合物偶氮苯 （AB） 作为碱性电解质下 APB 的负极材料，其氧化还原电位约为 -0.6 V（相对于 Hg/HgO）。AB 负极在 10 A g-1 的高电流密度下实现了 151 mAh g-1 的高倍率容量，并在 2 M KOH 电解液下在 12,500 次循环中具有出色的循环稳定性。实验结果和理论计算证实，AB 进行双电子氧化还原反应，涉及一个中心 N = N 基团和来自 H2O 分子的两个质子。这项工作揭示了偶氮材料中的质子化，并促进了在先进质子二次电池中设计具有多电子氧化还原反应的小有机分子的新见解。