期刊
ACS CATALYSIS
卷 8, 期 4, 页码 2923-2934出版社
AMER CHEMICAL SOC
DOI: 10.1021/acscatal.8b00248
关键词
lithium-oxygen batteries; RuO2/MnO2; practical applications; monolith cathode; high areal capacity
资金
- Basic Science Research Program of the National Research Foundation of Korea (NRF), Korean Ministry of Science, and ICT [NRF-2014R1A2A1A11049801, NRF-2017R1A5A1014708]
- Engineering Research Center of Excellence (ERC) Program of the National Research Foundation of Korea (NRF), Korean Ministry of Science, and ICT [NRF-2014R1A2A1A11049801, NRF-2017R1A5A1014708]
Despite their potential to provide high energy densities, lithium oxygen (Li-O-2) batteries are not yet widely used in ultrahigh energy density devices like electric vehicles, owing to various challenges, including poor cyclability, low efficiency, and poor rate capability, especially at high areal mass loading. Even the most promising Li-O-2 cells are unsuitable for practical applications, owing to a limited areal mass loading below 1 mg cm(-2), resulting in low areal capacity. Here, we demonstrate air cathodes of unprecedentedly high areal capacity at a high rate with sufficient cycle life for pragmatic operation of Li-O-2 batteries. A separator-carbon nanotube (CNT) monolith-type cathode of massive loading is prepared to achieve high areal capacity, but the cycle life and round-trip efficiency of CNT-only separator monolith cathodes are limited. The reversible and energy-efficient operation at high areal capacity and a high rate is enabled by adopting RuO2/MnO2 solid catalysts on the CNT (RMCNT). RMCNTs show a bifunctional catalytic effect in both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) and also completely decompose LiOH and Li2CO3 byproducts that may exist in discharged electrodes. This separator-RMCNT monolith offers beneficial features such as high mass loading, binder-free, intimate contact with the separator, and most importantly, catalysts for reversibility. Together, these features provide a remarkably long cycle life at unprecedentedly high capacity and high rate: 315, 45, and 40 cycles, with areal capacity limits of 1.5, 3.0, and 4.5 mAh cm(-2), respectively, at a rate of 1.5 mA cm(-2). Cycling is possible even at the curtailing capacity of 10 mAh cm(-2).
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