Nanosized Mn-Ru binary oxides as effective bifunctional cathode electrocatalysts for rechargeable Li-O2 batteries
Nanosized Mn-Ru binary oxides as effective bifunctional cathode electrocatalysts for rechargeable Li-O2 batteries
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DOI：
10.1039/c3ta13176a
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发表时间：
2014-01-01
影响因子：
11.9
通讯作者：
Yang, Hui
中科院分区：
文献类型：
--
作者：
Guo, Kun;Li, Yuan;Yang, Hui
通过水热法合成了 Mn-Ru 二元氧化物，并在非水 Li-O-2 二次电池中评估了它们作为空气电极双功能催化剂的性能。通过X射线衍射和透射电子显微镜对催化剂进行表征，证实所制备的氧化物含有γ-MnO2和水合RuO2，其形态分别为梭形纳米棒和纳米颗粒。线性扫描伏安测量表明，二元氧化物对氧还原和析氧反应均表现出显着的电催化活性。以Mn-Ru氧化物作为阴极催化剂的Li-O-2电池与单独使用科琴黑（KB）的电池相比，表现出更高的放电电压平台和更高的比容量（6500 mAh g（碳）（-1）），并且随后的充电电压约为6500 mA h g（碳）（-1）。比 KB 低 500 mV。此外，Li-O-2电池的循环性能大大提高，5次循环后容量保持率为73.2%。在1100 mA h g(carbon)(-1)的有限放电深度下，循环性能保持50次循环而没有急剧衰减，表明这种双功能电催化剂是锂空气电池中空气电极的有希望的候选者。
Mn-Ru binary oxides have been synthesized via a hydrothermal approach and their performance as bifunctional catalysts for the air electrode is evaluated in non-aqueous Li-O-2 secondary batteries. Characterization of the catalysts by X-ray diffractometry and transmission electron microscopy confirms that the as-prepared oxides contain gamma-MnO2 and hydrous RuO2 with the morphology of fusiform nanorods and nanoparticles, respectively. Linear scanning voltammetric measurements reveal that the binary oxides exhibit remarkable electrocatalytic activities towards both the oxygen reduction and oxygen evolution reactions. Li-O-2 batteries with Mn-Ru oxides as cathode catalysts show a higher discharge voltage plateau and a higher specific capacity of 6500 mA h g(carbon)(-1) than those with Ketjen black (KB) alone, and the subsequent charge voltage is ca. 500 mV lower than that with KB. Moreover, much enhanced cyclability of Li-O-2 batteries is achieved with a capacity retention ratio of 73.2% after 5 cycles. The cyclability is maintained for 50 cycles without sharp decay under a limited discharge depth of 1100 mA h g(carbon)(-1), suggesting that such a bifunctional electrocatalyst is a promising candidate for the air electrode in Li-air batteries.