Tuning the structure and morphology of Li2O2 by controlling the crystallinity of catalysts for Li-O2 batteries

Large overpotential in oxygen reduction and evolution reactions is the intractable obstruction of Li-O 2 batteries, causing inferior round-trip efficiency and diminished cycle life. Modulating the reaction mechanism of Li 2 O 2 is of crucial importance for a high-performance Li-O 2 battery. Herein, we report a composite of amorphous RuO 2 nanoparticles decorated carbon nanotubes (A-RuO 2 @CNT) as an efficient catalyst for Li-O 2 batteries. The amorphous catalyst contains abundant defects and vacancies as well as distorted atom arrangements, which provide sufficient active sites for reactions and enhance the affinity for LiO 2 intermediates. As a result, the formation/decomposition mechanisms of Li 2 O 2 are reasonably regulated. An amorphous film-like Li 2 O 2 product forms and uniformly deposits on the surface of A-RuO 2 @CNT, thus achieving faster redox kinetics and smaller overpotential. When used in Li-O 2 batteries, the amorphous catalyst affords remarkably decreased charge overpotential and enhanced cyclic stability, which is superior to its crystalline counterpart.