Despite their potential to provide high energy densities, lithium–oxygen (Li–O₂) batteries are not yet widely used in ultrahigh energy density devices like electric vehicles, owing to various challenges, including poor cyclability, low efficiency, and poor rate capability, especially at high areal mass loading. Even the most promising Li–O₂ cells are unsuitable for practical applications, owing to a limited areal mass loading below 1 mg cm^–2, resulting in low areal capacity. Here, we demonstrate air cathodes of unprecedentedly high areal capacity at a high rate with sufficient cycle life for pragmatic operation of Li–O₂ batteries. A separator-carbon nanotube (CNT) monolith-type cathode of massive loading is prepared to achieve high areal capacity, but the cycle life and round-trip efficiency of CNT-only separator monolith cathodes are limited. The reversible and energy-efficient operation at high areal capacity and a high rate is enabled by adopting RuO₂/MnO₂ solid catalysts on the CNT (RMCNT). RMCNTs show a bifunctional catalytic effect in both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) and also completely decompose LiOH and Li₂CO₃ byproducts that may exist in discharged electrodes. This separator-RMCNT monolith offers beneficial features such as high mass loading, binder-free, intimate contact with the separator, and most importantly, catalysts for reversibility. Together, these features provide a remarkably long cycle life at unprecedentedly high capacity and high rate: 315, 45, and 40 cycles, with areal capacity limits of 1.5, 3.0, and 4.5 mAh cm^–2, respectively, at a rate of 1.5 mA cm^–2. Cycling is possible even at the curtailing capacity of 10 mAh cm^–2.

中文翻译：

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基于RuO ₂ / MnO ₂负载在CNT上的RuO ₂ / MnO ₂双功能电催化剂的实用型Li–O ₂电池，具有高循环寿命的高速率和高容量空气阴极

尽管锂-氧（Li-O ₂）电池具有提供高能量密度的潜力，但由于其面临的诸多挑战，包括循环性差，效率低和倍率性能差等问题，尚未广泛用于电动汽车等超高能量密度的设备中，特别是在较高的区域质量负载下。甚至最有前途的Li–O ₂电池由于在1 mg cm ^–2以下的有限的区域质量负载，也不适合实际应用，从而导致较低的区域容量。在这里，我们演示了高容量的空阴极，具有高循环速率，并具有足够的循环寿命，可用于Li-O _2的实际操作电池。为了获得高的面积容量，准备了高负载的隔板-碳纳米管（CNT）整体式阴极，但是仅CNT的隔板整体式阴极的循环寿命和往返效率受到限制。通过在CNT（RMCNT）上采用RuO ₂ / MnO ₂固体催化剂，可以在高面积容量和高速率下实现可逆且节能的操作。RMCNTs在氧还原反应（ORR）和氧释放反应（OER）中均显示出双功能催化作用，并且还可以完全分解LiOH和Li ₂ CO ₃放电电极中可能存在的副产物。这种分离器-RMCNT整体材料具有有益的功能，例如高质量负载，无粘合剂，与分离器紧密接触，最重要的是，可逆性催化剂。这些功能一起提供了前所未有的高容量和高速率的超长循环寿命：315、45和40个循环，面积容量限制分别为1.5、3.0和4.5 mAh cm ^–2，速率为1.5 mA厘米^–2。即使缩减容量为10 mAh cm ^–2，也可以进行循环。