Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
The discharge performance of the cathodes was tested in a nonaqueous lithium-air battery that consisted of a lithium foil anode, a glass-fiber separator (Whatman GF/C), and 250 μL 1 M LiTFSI (Sigma-Aldrich, 99.95%) in TEGDME (Sigma-Aldrich, 99%) as the electrolyte to fully saturate the cathode. The entire battery was assembled in an argon-filled glove box (Etelux, Lab 2000) at water and oxygen contents below 1 ppm. All tests were performed at room temperature (25 °C) at the constant oxygen pressure of 1 atm by the battery cycling system (Neware, CT-3008W).
The microscopic structure of the cathode was observed by a scanning electron microscope (SEM, JEOL Inc., JSM-6300) under an acceleration voltage of 20 kV. The discharge product compositionwas analyzed by a Philips high resolution X-ray diffraction system (XRD, model PW 1825) using a Cu-Kα source operating at 40 keV.