Abstract:The cathodic catalysts, which play a key role in lithium air batteries, have significant influence on the polarization,power density, cyclic ability and energy efficiency of batteries. In this work, we study on the transition metal oxides to to develop cheaper and efficient catalyst for lithium air batteries.Various transition metal oxides, carbon nanotubes/cobalt manganese oxides composites and Fe2O3nanoflakes were synthesized and investigated as catalysts for lithium air batteries. The as-prepared products were characterized by X-ray diffraction(XRD), infrared spectroscopy (FTIR), N2isothermal adsorption stripping, scanning electron microscope (SEM), transmission electron microscopy (TEM). Cyclic voltammograms (CV), linear sweep (LSV), acimpedance (EIS), charge-discharge cycle performance were used to research on the influence of electrochemical characterization on batteries. The results are presented as follows:1. The composites of MnO2/CNTs, Fe2O3/CNTs, NiO/CNTs and Co3O4/CNTs were synthesized by hydrothermal methods. MnO2/CNTs show better discharge performance, and Co3O4/CNTs show better charge performance for lithium air batteries. The different mass ratio of MnO2/CNTs and Co3O4/CNTs were studied. With the content increase of MnO2/CNTs, the discharge performance improves, and the charging performance has a tendency to reduce. The batteries have the lowest discharge-charge voltage gap of~1.5V, when the mass ratio of MnO2/CNTs and Co3O4/CNT was3:2.2. The Carbon Nanotubes/Cobalt Manganese Oxides composites with different Co and Mn contents were prepared by a precipitation method. With the content increase of Mn, the discharge performance improves, and the charging performance reduces. The product at the Co/Mn rate of3:1has a minor charge-discharge voltage difference(△V) of1.05V. The discharge products have Li2CO3and Li2O2, which reveals that the carbonate electrolyte maybe decompose in lithium air batteries.3. The well crystallized rhombohedral Fe2O3nanoflakes with an average diameter of~90nm were successfully synthesized via a simple hydrothermal synthesis method and employed as the catalyst for non-aqueous Li-air batteries. The Fe2O3nanoflakes showed superior catalytic properties for both ORR and OER in Li-air batteries, leading to reduced discharge-charge overpotentials of a-0.83V voltage gap. The batteries also revealed considerable rate capability and cyclic ability, which retains considerable rate capability of2000mAh/geiectrode at a high current density of0.4mA/cm2, and stable capacity performance after30cycles. |