Unraveling the catalytic activities of ruthenium nanocrystals in high performance aprotic Li–O2 batteries. (October 2016)

• Record Type: Journal Article
• Authors: Sun, Bing; Guo, Limin; Ju, Yuhang; Munroe, Paul; Wang, Erkang; Peng, Zhangquan; Wang, Guoxiu
• Is Part Of: Nano energy. Volume 28(2016:Oct.)
• Page Start: 486
• Page End: 494
• Publication Date: 2016-10
• Subjects: Aprotic lithium–oxygen battery -- Ruthenium nanocrystals -- Catalysts -- Differential electrochemical mass spectrometry -- Oxygen reduction/evolution reaction; 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.2016.08.057
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Ruthenium (Ru)-catalyzed aprotic Li–O2 batteries have attracted a great deal of interests because of their excellent electrochemical performances including high specific energy and round-trip efficiency. However, it remains unclear how the incorporated Ru catalysts function to enhance the batteries' performance. Herein, we report Ru nanocrystal-catalyzed carbon nanotube-based aprotic Li–O2 batteries with electrochemical performances that can match or even surpass some of the best literature results. The catalytic mechanism of Ru nanocrystals has been studied by a combination of Coulometry and in situ differential electrochemical mass spectrometry (DEMS). It has been found that through the synergy of water additive in electrolyte and Ru-based catalysts, the charging reaction overpotential can be brought down to 0.12 V (usually η>1 V). Moreover, an isotope-labeled DEMS study on the electrochemical oxidation of Li2 13 CO3 indicated that Ru nanocrystals also have the capability to decompose Li2 CO3, a detrimental by-product formed in almost all aprotic Li–O2 batteries, at a surprisingly low potential of ~3.5 V vs. Li/Li + (usually >4.0 V). The capabilities of Ru nanocrystals to decompose Li2 O2, LiOH, and Li2 CO3 at low voltages, which drastically decreases the degradation of electrode and/or electrolyte, are crucial to achieve outstanding electrochemical performances for Li–O2 batteries. Graphical abstract: Highlights: Ru-based catalysts reduce the charging reaction overpotential down to 0.12 V. An isotope-labeled DEMS study indicated that Ru catalyse Li2 CO3 decomposition. Water in electrolyte changes the reaction mechanism of Li-O2 batteries.