Rechargeable lithium–air (O2) batteries have received much attention due to their extremely high theoretical energy densities, which far exceeds that of current lithium-ion batteries. The considerable high energy densities come from (i) pure metal lithium as anode and (ii) the cathode oxidant, oxygen, which comes from the surrounding air. However, there are still many scientific and technical challenges especially nanomaterial challenges to overcome before it turns into reality. In this review, the fundamental principles and understanding of the electrochemical reaction in the aprotic lithium–air batteries are first presented. We emphasized on the discussion of the nanomaterial's issues which prevent their practical implementation, including the material status and challenges from cathode, electrolyte, anode and other components. These problems will be discussed in detail and possible solutions are also suggested. Finally, we explore future research directions in the field of aprotic rechargeable lithium–air batteries.