Experimental and Modeling Studies of Transport Limitations in Lithium‑O2 Battery

Abstract

The Li‑O2 battery is one of the promising technologies to meet the ever-growing energy demand of the modern world. The theoretical energy density of Li‑O2 battery could be as high as 2.8 kWh/kg due to the high energy density of anode lithium metal and an unlimited supply of oxygen from ambient air as the cathode active material. However, several technical challenges (e.g. unstable electrolytes, limited mass transport, low round-trip efficiency) remain unsolved and have hindered its commercialization. In this study, experimental and modeling methods are used to investigate mass transport properties of Li‑O2 battery using organic electrolytes. Discharge products (mainly Li2O2) are not soluble in organic electrolytes and precipitate at the reaction sites in the porous cathode electrode where the oxygen reduction reaction (ORR) happens. This pore blockage and film formation would further decrease the oxygen and lithium ion transport in the cathode electrode. This study experimentally examined the influence of oxygen cathode open ratio and lithium salt concentration on specific discharge‑charge capacity of the battery at various current densities. The model simulation in this study investigated the evaporation of electrolyte at different oxygen cathode open ratios and the impact on battery performance in detail. Multiple approaches are proposed to optimize the battery performance based on its applications and working conditions.