Highly-efficient MnO₂/carbon array-type catalytic cathode enabling confined Li₂O₂ growth for long-life Li-O₂ batteries

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• 作者：Fangfang Tu^a ; ^b ; Qiannan Wang^a ; ^c ; Jian Xie^a ; ^d ; ^{xiejian1977@zju.edu.cn} ; Gaoshao Cao^d ; Shichao Zhang^e ; Jiangwei Wang^a ; ^c ; ^{jiangwei_wang@zju.edu.cn} ; Scott X. Mao^c ; Xinbing Zhao^a ; ^d ; Hui Ying Yang^b ; ^{yanghuiying@sutd.edu.sg}
• 关键词：Lithium&ndash ; oxygen battery ; MnO2/carbon submicron tube ; Array-type electrode ; Confined Li2O2 growth ; In situ electrochemistry
• 刊名：Energy Storage Materials
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：6
• 期：Complete
• 页码：164-170
• 全文大小：1710 K
• 卷排序：6

文摘

Li–O2 batteries recently have attracted intensive research interest because of the rather high energy density. The electrochemical performance of Li–O2 batteries, however, is largely limited by the insulating and reactive Li2O2, which necessitates a renovation on the design of catalytic cathodes. In this work, we propose a unique MnO2/carbon submicron tube (MnO2/CST) array-type catalytic cathode capable of controlling Li2O2 growth spatially and structurally. The high catalytic activity of ultrathin MnO2 nanosheets enables conformal growth of thin-layered Li2O2 on the MnO2 sheets, which relieves or defers electrode deactivation upon discharge and renders easy catalytic decomposition of Li2O2 upon charge. In situ transmission electron microscopy characterization confirms the presence of Li2O2 on discharged MnO2/CST and reveals the phase transition and morphology changes upon charge. The array-type architecture of the catalytic cathode facilitates barrier-free transportation of oxygen gas and Li ions. The absence of polymer binder and the reduced carbon exposure to Li2O2 (or LiO2) exclude or minimize the parasitic reactions related to binder and carbon. As a result, Li–O2 cells with MnO2/CST catalytic cathode exhibit superior cycling stability and low polarization. At 800 mA g–1, the cell can sustain a stable cycling of over 300 cycles at a limited capacity of 1000 mAh g–1.