Highly efficient Ru/B4C multifunctional oxygen electrode for rechargeable LiO2 batteries
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.
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