Single Wall Carbon Nanotube Modified with Nano Size Metal Oxides for High-Performance Cathode in Li-O2 Rechargeable Batteries

Li-O 2 batteries have a big potential for the application of future electrochemical power sources because of their much larger energy density than that of conventional Li ion battery. However, rechargeable Li-O 2 batteries are still facing many challenges including large overpotential, low round trip efficiency, low power capability, and poor cycle stability. All these poor electrochemical performances are related with poor reversibility of air electrode, which can be improved by employing sophisticated and active cathode [1]. As confirmed in our early study [2], a mesoporous oxide can virtually reduce the overpotential and enhance the cycle efficiency with abundant active sites. In addition, as a carbon substrate, a CNT has high chemical and thermal stability, high tensile strength and excellent electrical conductivity resulting from their unique structures. Discharge capacity of 1200 mAh/g was achieved on Li-O 2 battery using CNT for cathode, however, because of high charge potential, cycle performance was poor. In this study, therefore, we introduce combination of single wall carbon nanotubes (SWCNT) and mesoporous metal oxides as a cathode for Li-O 2 batteries. It was found that discharge capacity was decreased by loading mesoporous MnO 2 , cycle stability was much increased, in particular, co-loading of Co 3 O 4 and Cr 2 O 3 shows much superior cycle stability and discharge capacity was sustained up to 100 cycles. Characterization techniques ranging from, electron microscopy, surface analysis have been applied for metal oxides. Large porosity formed in SWCNT electrode seems to be one reason for large discharge capacity and cycle stability. References [1] Z. Ma, X. Yuan, L. Li, Z.F. Ma, D. P. Wilkinson, L .Zhang, J. Zhang, Energy & Environmental Science , 8 , 2044 (2015). [2] A. K. Thapa, Y. Hidaka, H. Hagiwara, S. Ida, T. Ishihara, J. Electrochem. Soc. , 158 , A1483(2011)