Research on Effective Oxygen Window Influencing the Capacity of Li–O2 Batteries

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• 作者：Jie Jiang ; Han Deng ; Xiang Li ; Shengfu Tong ; Ping He ; Haoshen Zhou
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：April 27, 2016
• 年：2016
• 卷：8
• 期：16
• 页码：10375-10382
• 全文大小：474K
• 年卷期：0
• ISSN：1944-8252

文摘

Li–O<sub>2sub> batteries have attracted extensive attention recently due to the extremely huge specific energy. Similar to research mode of Li-ion batteries, nowadays specific capacity based on the mass of cathode material is widely adopted to evaluate the electrochemical performance of Li–O<sub>2sub> batteries. However, the prerequisite of linear correlation between the delivered capacity and active mass is easily neglected. In this paper, we demonstrate the rationality of specific capacity adopted in Li-ion batteries with classic LiCoO<sub>2sub> cathode by confirming the linear correlation between cell capacity and LiCoO<sub>2sub> mass. Delivered capacities of Li–O<sub>2sub> batteries with different cathode masses are simultaneously measured and nonlinear correlation is obtained. The discharge and charge products are identified by X-ray diffraction and in situ gas chromatography-mass spectrometry analysis to ensure reaction mechanism. Discharge capacities of Li–O<sub>2sub> batteries with various areas of oxygen window are further studied, which shows that cell capacity increases linearly with the area of oxygen window. Scanning electron microscopy is employed to observe the discharged electrode and shows that Li<sub>2sub>O<sub>2sub> deposition during discharge mainly occurs in the electrode area exposure to the oxygen, which is consequently defined as effective area for accommodating Li<sub>2sub>O<sub>2sub>. Moreover, a plausible route for formation of effective area in the oxygen electrode is proposed. These results provide evidence that effective area is an equally important factor determining cell capacity.