A Synergistic Catalytic Mechanism for Oxygen Evolution Reaction in Aprotic Li-O-2 Battery

作者：Cai, Senrong; Zheng, Mingsen; Lin, Xiaodong; Lei, Ming; Yuan, Ruming^*; Dong, Quanfeng^*

来源：ACS Catalysis, 2018, 8(9): 7983-7990.

DOI：10.1021/acscatal.8b02236

• Li-O-2 battery
• OER catalyst
• synergistic mechanism
• density functional theory
• low charge overpotential

The large polarization of a Li-O-2 battery is derived from oxygen evolution reaction (OER) processe. To achieve a long life Li-O-2 battery with high round-trip efficiency, various catalysts have been extensively investigated for oxygen cathodes, especially for OER processes. Here, we designed an in situ growth of alpha-MnO2/RuO2 composite on a graphene nanosheet with a carbon embedded structure as the cathode electrode for a Li-O-2 battery. The synergistic catalytic effect between the alpha-MnO, and RuO2 has significantly improved the OER kinetics. The fabricated Li-O-2 battery can deliver a high reversible capacity of 2895 mAh/g(composite) with a low charge overpotential of 0.25 V (0.34 V lower than bare RuO2 cathode). The results revealed that more LiO2 intermediates formed when alpha-MnO2 was introduced into the RuO2 electrode during the oxidation of Li2O2. The facilitation of the initial Li extraction was confirmed by density functional theory (DFT) calculations, which shows that the alpha-MnO, and RuO2 interfaces can stabilize the primary Li ions and Li2-xO2 intermediates, respectively. Subsequently, Li2-xO2 would be easily oxidized to O-2 by RuO2 catalyst. With the synergy between alpha-MnO, and RuO2, the initial delithiation process and O-2 evolution are promoted simultaneously. By combining theoretic and experimental results, we proposed a synergistic catalytic mechanism for the OER processes.

• 出版日期2018-9
• 单位厦门大学