Operando observations of RuO2 catalyzed Li2O2 formation and decomposition in a Li-O2 micro-battery. (May 2018)

• Record Type: Journal Article
• Authors: Hou, Chen; Han, Jiuhui; Liu, Pan; Yang, Chuchu; Huang, Gang; Fujita, Takeshi; Hirata, Akihiko; Chen, Mingwei
• Is Part Of: Nano energy. Volume 47(2018)
• Page Start: 427
• Page End: 433
• Publication Date: 2018-05
• Subjects: RuO2 catalyst -- Lithium-oxygen battery -- Scanning transmission electron microscopy -- Liquid cell electron microscopy; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2018.02.057
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: RuO2 displays excellent bifunctional catalysis towards the oxygen reduction and evolution reactions of Li-O2 battery. Nevertheless, how the solid catalyst successively catalyzes solid Li2 O2 formation and decomposition, confronting passivation and loss of RuO2 /Li2 O2 contact, during discharging and charging remains a mystery. Here we report operando observations of RuO2 catalyzed oxygen reduction and evolution reactions of Li2 O2 by utilizing a liquid cell scanning transmission electron microscope. Upon discharging, RuO2 obviously accelerates formation of soluble LiO2 intermediates and acts as preferential sites of Li2 O2 precipitation. During charging, the catalytic activation of RuO2 takes place at electrolyte-RuO2 -Li2 O2 triple-phase interfaces. Importantly, RuO2 not only catalyzes the decomposition of directly contacted Li2 O2, but also promotes oxidation of soluble LiO2 for rapid dissolution of isolated Li2 O2 nanoparticles by a chemical comproportionation reaction. The observation unveils how RuO2 catalyzes the formation and decomposition of Li2 O2 during discharging and charging and provides nanoscale insights into cathodic reactions of Li-O2 batteries with solid catalysts. Graphical abstract: Operando observations of RuO2 catalyzed Li2 O2 formation and decomposition in a liquid Li-O2 micro-battery are conducted by Cs-corrected scanning transmission electron microscopy. The real-time and real-space observations with simultaneous electrochemical measurements unveil the reaction mechanisms of RuO2 catalyzed the formation and decomposition of solid and insulating Li2 O2 during discharge and charge. fx1 Highlights: RuO2 catalyzed cathodic reactions in Li-O2 batteries were investigated by nano-scale operando observations. The mechanisms of RuO2 nanoparticles catalyzing the formation and decomposition of Li2 O2 were unveiled. A hybrid chemical/electrochemical pathway of Li2 O2 decomposition by a comproportionation reaction was revealed. This result is important in designing high-performance cathodes of Li-O2 batteries.