Irreversible parasitic reactions and the resulting accumulation of insulating side products are main barriers for practical application of rechargeable lithium–oxygen (Li O 2 ) batteries . Therefore, it is critical to develop multifunctional oxygen electrodes suitable for oxygen reduction reaction , oxygen evolution reaction , and decomposition of side reaction products. Here we report the application of ultrafine ruthenium on boron carbide (Ru/B 4 C) with highly efficient multifunctional activities as carbon-free oxygen electrodes for Li O 2 batteries. Li 2 CO 3 and LiOH can be completely decomposed by Ru/B 4 C at 4.0 V and 4.1 V, respectively, within the stability window of the electrolyte. A Li O 2 battery using the Ru/B 4 C oxygen electrode achieves low overpotentials for Li O 2 reactions, and excellent cycling performance under the capacities of 300 and 500 mAh g −1 Ru/B4C . In-situ gas chromatography analysis reveals that O 2 is the major gas product during charging. Only a negligible amount of CO 2 is observed in the first charging process. Therefore, Ru/B 4 C can be a very promising oxygen-electrode material for Li O 2 batteries and Li–air batteries operated in ambient air.
Shiyu Ma,Qingchao Liu,Dongling Lei,Xiaoqing Guo,Shunfang Li,Zhongjun Li
Issues with the sluggish kinetics of oxygen reduction and oxygen evolution reduction hinder the advance of Li O 2 batteries for next-generation energy storage. To alleviate these problems, Cu 2 O nanoparticles with different crystal planes have been synthesized via a simple solution reaction and characterized as a bi-functional catalyst for non-aqueous Li O 2 battery. In this work, catalytic behaviour of Cu 2 O nanoparticles with different crystal planes are initially explored and it is found that the Cu 2 O nanoparticles exposing {111} crystal planes exhibit the most catalytic performance compared with other crystal planes, which is further confirmed by using first-principles computations. Inspired by selectively catalytic behaviour of crystal plane, porous Cu 2 O nanoframes exposed with eight {111} crystal planes and higher surface area derives from all-corner-truncated rhombic dodecahedron Cu 2 O nanoparticles are synthesized, which can act as highly activity three-dimensional cathode in a typical Li O 2 battery after being directly combined with carbon nanotubes by electrostatic interaction . Thanks to the excellent catalytic activity of carbon nanotubes-Cu 2 O nanoframes and unique cathode structure, batteries with this cathode display an enhanced electrochemical performance including superior round-trip efficiency, excellent cycling performance and high specific capacity.
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