College of Chemistry and Molecular Sciences, Hubei Key Lab of Electrochemical Power Sources, Wuhan University , Wuhan 430072, China.
ACS Appl Mater Interfaces. 2017 Jun 14;9(23):19800-19806. doi: 10.1021/acsami.7b02663. Epub 2017 Jun 5.
In this work, a planar model electrode method has been used to investigate the structure-activity relationship of multiple noble and 3d metal catalysts for the cathode reaction of Li-O battery. The result shows that the battery performance (discharge/charge overpotential) strongly depends not only on the type of catalysts but also on the morphology of the discharge product (LiO). Specifically, according to electrochemical characterization and scanning electron microscopy (SEM) observation, noble metals (Pd, Pt, Ru, Ir, and Au) show excellent battery performance (smaller discharge/charge overpotential), with wormlike LiO particles with size less than 200 nm on their surfaces. On the other hand, 3d metals (Fe, Co, Ni, and Mn) offered poor battery performance (larger discharge/charge overpotential), with much larger LiO particles (1 μm to a few microns) on their surfaces after discharging. Further research shows that a "volcano plot" is found by correlating the discharging/charging plateau voltage with the adsorption energy of LiO on different metals. The metals with better battery performance and worm-like-shaped LiO are closer to the top of the "volcano", indicating adsorption energy of LiO is one of the key characters for the catalyst to reach a good performance for the oxygen electrode of Li-O battery, and it has a strong influence on the morphology of the discharge product on the electrode surface.
在这项工作中，我们使用平面模型电极方法研究了多种贵金属和 3d 金属催化剂对于锂氧电池阴极反应的结构-活性关系。结果表明，电池性能（放电/充电过电位）不仅取决于催化剂的类型，还取决于放电产物（LiO）的形态。具体而言，根据电化学特性和扫描电子显微镜（SEM）观察，贵金属（Pd、Pt、Ru、Ir 和 Au）表现出优异的电池性能（较小的放电/充电过电位），其表面具有尺寸小于 200nm 的蠕虫状 LiO 颗粒。另一方面，3d 金属（Fe、Co、Ni 和 Mn）的电池性能较差（较大的放电/充电过电位），放电后其表面的 LiO 颗粒较大（1μm 至几微米）。进一步的研究表明，通过将放电/充电平台电压与 LiO 在不同金属上的吸附能相关联，发现了一个“火山图”。具有更好电池性能和蠕虫状 LiO 的金属更接近“火山”的顶部，这表明 LiO 的吸附能是催化剂在 Li-O 电池的氧电极上达到良好性能的关键特征之一，并且对电极表面上放电产物的形态有很强的影响。
