Ru single atoms induce surface-mediated discharge in Na-O2 batteries |
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| Institution: | 1. National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China;2. Dalian National Laboratory for Clean Energy & State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian 116023, China;3. State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China;4. Nanjing IPE Institute of Green Manufacturing Industry, Nanjing 211100, China |
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| Abstract: | Sodium (Na) O2 batteries have high energy density and low cost. However, high polarization, complex discharge products, and low Coulombic efficiency (CE) lead to poor cyclability. Here, we proposed an atomically dispersed Ru catalyst on nitrogen-doped graphene for Na-O2 batteries. The catalysts enable the discharge to proceed via a surface-mediated route, which leads to uniform deposition of Na2-xO2 and low polarization during recharge. The first-principle calculation revealed that Ru-N4 complex in the catalyst has strong chemical adsorption to intermediate superoxides, facilitating uniform deposition and enhancing rapid kinetics. In contrast, Ru nanoparticles, despite the catalytic activity, induce bulk deposition via a solution-mediated route because the exposed graphene surface shows weak interaction to superoxides, thereby lowering CEs and cyclability. In brief, the atomically-dispersed Ru catalyst endows Na-O2 batteries with excellent electrochemical properties via a surface-mediated discharge. |
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