RuO2/MnO2 Nanorods As High Efficient Electrocatalyst of Lithium-Oxygen Battery

Abstract

Electrocatalyst is the key component in Li-O2 batteries and attracted extensive attention in recent years. It has demonstrated that carbon materials1, transitional metal oxides2, noble metals3, and Perovskite-type oxides4 can present high catalytic activity in oxygen reduction reaction (ORR) or in oxygen evolution reaction (OER) to facilitate decomposition of Li2O2. In order to explore high efficient electrocatalyst, in the present work, RuO2/MnO2 nanorods were synthesized via a facile two-step hydrothermal reaction. Li-O2 battery testing results demonstrated that the as-synthesized RuO2/MnO2 nanorods exhibit excellent properties as electrocatalyst of oxygen cathode. The RuO2/MnO2 nanorods could maintain a reversible capacity of 500 mAh g-1 in 75 cycles at a rate of 50mA g-1, and a higher capacity of 4000 mAh g-1 in 20 cycles at a rate of 200mA g-1. Moreover, the RuO2/MnO2 nanorods present a much lower voltage polarization in charge/discharge processes than MnO2 nanorods electrode does. The catalytic activities of RuO2/MnO2 nanorods and MnO2 nanorods were also compared by studies of rotating disk electrode (RDE). Furthermore, in situ high-energy X-ray diffraction and ex situ SEM were carried out to investigate the formation and decomposition of the discharge products Li2O2. Figure 1. (a)(b) In-situ XRD patterns of the electrode in discharge process for 20 h. (c) Charge/discharge curves of RuO2/MnO2 nanorods at a rate of 50 mA g-1. ACKNOWLEDGMENT: This work was financially supported by NSFC (Grant Nos. 21373008, 21321062, 21273184) REFERENCES: (1) Liu, T.; Leskes, M.; Yu, W.; Moore, A. J.; Zhou, L.; Bayley, P. M.; Kim, G.; Grey, C. P., Science 2015, 350, 530-533. (2) Zhang, P.; Sun, D.; He, M.; Lang, J.; Xu, S.; Yan, X., ChemSusChem 2015, 8, 1972-1979. (3) Bruce, P. G., Science 2012, 337, 563-566. (4) Xu, J. J.; Xu, D.; Wang, Z. L.; Wang, H. G.; Zhang, L. L.; Zhang, X. B., Angewandte Chemie 2013, 52, 3887-90. Figure 1