Enhanced performance of Li-O2 battery based on CFx/C composites as cathode materials

A hybrid air-electrode composed of a mixture of fluorinated carbon (CF x ) and Ketjen black (KB) active carbon composite materials was prepared to improve performance of Li-O 2 battery . In the hybrid air-electrodes, four kinds of CF x materials including fluorinated graphite, fluorinated carbon fiber, fluorinated coke and fluorinated black carbon were utilized as lithium insertion materials. The physical properties and morphologies of the KB and CF x carbon materials were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Scanning electron microscopy (SEM) measurements. Compared with the conventional KB air-electrode, all the CF x /KB hybrid air-electrodes in Li-O 2 batteries showed higher specific discharge capacity, especially at high current density . Among these CF x /KB hybrid air-electrodes, the fluorinated graphite based electrode showed the best electrochemical performance in Li-O 2 battery due to its highest discharge capacity of the fluorinated graphite material in the Li/CF x primary battery, highest specific surface area, and highest total pore volume . The electrochemical performance of Li-O 2 and Li-air batteries using the hybrid air-electrodes with the different fluorinated graphite: KB weight ratio, including specific charge and discharge capacity, cycling stability and rate capability were systematically investigated. At a current density of 0.5   mA   cm −2 , the fluorinated graphite based air-electrode delivered a high specific discharge capacity of 1138   mAh   g −1 in Li-O 2 batteries, which was more than four times than that of the conventional KB air-electrode (265   mAh   g −1 ) under same testing conditions. The battery assembled with the fluorinated graphite based air-electrode exhibited better cycling stability than that of the battery assembled with the conventional KB air-electrode.