The importance of anode protection towards lithium oxygen batteries

Developing lithium oxygen (Li–O2) batteries is critical to achieve high energy density in energy storage devices. Benefiting from the low weight of the cathode reagent, oxygen, Li–O2 batteries possess a high theoretical energy density of 3500 W h kg−1 based on the formation of Li2O2. However, they face several challenges from the metal anode, the air electrode, and the unstable electrolyte. Although most studies have focused on the air electrode, the importance of the anode protection should not be neglected. In this review, we aim to understand the challenges on the lithium anode in Li–O2 batteries, which include Li dendrite growth, parasitic reactions between Li and active species in the electrolyte, and the oxygen crossover effect. Also, recent advances on the Li protection in Li–O2 batteries will be introduced. This review emphasizes the importance of anode protection especially in an oxygen rich environment and could provide guidance for future development of Li–O2 batteries.