Study On Dual Function Oxygen Electrode Of Lithium Air Battery In Organic System

Li-air batteries have a large theory capacity of 3860 mAh g-1 and huge theory energy of 11,400 Wh kg-1. And also Li-air batteries are friendly to environment. If successfully developed, this battery could provide an energy source for electric vehicles rivaling that of gasoline in terms of usable energy density. In recent years, researchers have made some preliminary research results. However, the investigation on lithium-air batteries is still in its initial stage. The most critical factor, limiting the practical application of lithium-air batteries, is the dynamic defects of cathodic reactions. We should find a suitable catalyst to increase the rate of reaction kinetics of cathode. This paper focuses on the preparation of air electrode and the basic research of bi-functional electrocatalyst based on oxygen reduction/oxygen evolution reaction. The major research contents are presented as follows:Ba0.9Co0.7Fe0.2Nb0.1O3-δ (BCFN9721) perovskite oxide was prepared and applied as a bi-functional electro-catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Lithium oxygen battery with an oxygen electrode composed of 80% Ketjen Black (KB) and 20% BCFN9721 delivered a discharge voltage platform of 2.63 V, which is the highest among different composition ratios of KB and BCFN9721 in the oxygen electrodes. Adding 20% BCFN9721 into KB could effectively reduce the polarization, especially for the OER. The lithium oxygen battery using BCFN9721 perovskite oxide as the electro-catalyst could run stably for 24 discharge/charge cycles with a fixed capacity of 1000 mAh.g-Ielectrode.The charge polarization could be significantly reduced by BCFN9721 catalyst, thus alleviating the formation of undesired discharge products caused by the corrosion of carbon and decomposition of the electrolyte.Three-dimensional macroporous MnO2 and LaNiO3-δ materials were synthesized, which were used as oxygen electrode catalysts of lithium-oxygen battery, and their electrochemical properties were measured. When three-dimensional macroporous MnO2 was used as oxygen electrode catalyst of the battery, its first discharge capacity could be up to 3000 mAh g-1 electrode. During the process of fixed capacity measurement, this battery could run stably for 10 discharge/charge cycles, which indicated that used MnO2 as oxygen electrode catalyst of lithium-oxygen battery could promote the process of oxygen reduction reaction and oxygen evolution reaction. For the battery of using LaNiO3-δ material as oxygen electrode catalyst, its first discharge capacity was around 2600 mAh g-1 electrode. For the process of fixed capacity measurement, it could run stably for 9 discharge/charge cycles, which demonstrated the catalyst could promote the process of oxygen reduction reaction and oxygen evolution reaction in some degree.