Because of the sluggish kinetics of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), binary ruthenium–tin oxides synthesized by a hydrothermal method with postannealing at 450 °C for 2 h are first proposed as bifunctional catalysts for these two reactions on the air electrode of rechargeable zinc–air batteries. The binary Ru–Sn oxides in various compositions show the typical oxide solid solution in the rutile phase. Among all binary Ru–Sn oxides, RuSn73 (70 atom % RuO₂ and 30 atom % SnO₂) and RuSn37 (30 atom % RuO₂ and 70 atom % SnO₂) show the highest catalytic activities toward the OER and ORR, respectively. Consequently, a novel design of the air electrode consisting of a RuSn37 coating on the carbon paper and a Ti mesh coated with RuSn73 (denoted RuSn(37-C|73-Ti)) is proposed to possess the optimal charge–discharge performances. A unique cell employing such an air electrode has been demonstrated to exhibit a very low charge–discharge cell voltage gap of 0.75 V at 10 mA cm^–2. This cell with a peak power density of 120 mW cm^–2 at the current density of 235 mA cm^–2 also shows an outstanding charge–discharge stability over 80 h. This cell also exhibits an exceptionally high charge rate capability at 150 mA cm^–2 with a low charging voltage of 2.0 V.

中文翻译：

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设计具有最佳性能的可充电锌空气电池空气电极的二元Ru-Sn氧化物

由于氧释放反应（OER）和氧还原反应（ORR）的动力学缓慢，首先提出了通过水热法在450°C下进行2 h后退火的方法合成的二元钌-锡氧化物作为这两种反应的双功能催化剂在可充电锌空气电池的空气电极上。各种成分的二元Ru-Sn氧化物在金红石相中显示出典型的氧化物固溶体。在所有二元Ru-Sn氧化物中，RuSn73（70原子％的RuO ₂和30原子％的SnO ₂）和RuSn37（30原子％的RuO ₂和70原子％的SnO _2））分别显示出对OER和ORR最高的催化活性。因此，提出了一种新颖的空气电极设计，该空气电极由碳纸上的RuSn37涂层和涂有RuSn73的Ti网孔（表示为RuSn（37-C | 73-Ti））组成，具有最佳的充放电性能。事实证明，采用这种空气电极的独特电池在10 mA cm ^–2时显示出非常低的0.75 V充放电电池电压间隙。这种电池的峰值功率密度为120 mW cm ^-2，电流密度为235 mA cm ^-2，在80小时内也显示出出色的充放电稳定性。该电池还具有150 mA cm ^–2的超高充电速率能力和2.0 V的低充电电压。