Positive Electrodes of Non-Aqueous Rechargeable Lithium-Oxygen Batteries

Non-aqueous rechargeable lithium-oxygen battery (NRLOB) possesses the highest theoretical energy density among all secondary battery systems. However, there are some tough problems for the NRLOB development, which include poor cyclability and low charge-discharge current densities of the battery. These problems are chiefly relating to the electrochemical reactions on the surface of the porous oxygen positive electrode. The key issue should be to ensure reversible decomposition and formation of Li2O2 to proceed sustainedly at higher reaction rates. In this article, the fundamental understanding of oxygen electrochemical mechanisms in non-aqueous electrolytes, research status of carbon materials and catalysts of the positive electrode, electrode structures and side reactions arising from electrolyte degradation are reviewed. The main issues for further research are summed up.