Effects of Oxygen Partial Pressure on Li-Air Battery Performance | Samsung Advanced Institute of Technology

Abstract: For application in electric vehicles (EVs), the Li-air battery system needs an air intake system to supply dry oxygen at controlled concentration and feeding rate as the cathode active material. To facilitate the design of such air intake systems, we investigated the effects of oxygen partial pressure (≤1 atm) on the performance of the Li-air cell, which have not been systematically examined before. The amounts of consumed O2 and evolved CO2 from the Li-air cell were measured with a custom in situ differential electrochemical gas chromatography-mass spectrometry (DEGC-MS). The amounts of consumed O2 suggest that the oxygen partial pressure does not affect the reaction mechanism during discharge, and the two-electron reaction occurs under all test conditions. On the other hand, the charging behavior varies by the oxygen partial pressure. The highest O2 evolution ratio was attained under 70％ O2, along with the lowest CO2 evolution. The cell cycle life also peaks at 70％ O2 condition. Overall, an oxygen partial pressure of about 0.5？0.7 atm maximizes the Li-air cell capacity and stability at 1 atm condition. The findings here indicate that the appropriate oxygen partial pressure can be a key factor when developing practical Li-air battery systems.