High Rate Lithium Air Batteries Enabled by Redox Mediator Additives

The global energy demand has been predicted to increase by one-third during next few decades. This demand largely relies on the fossil fuels that are limited and detrimental to the environment by producing CO2 which leads to the global warming (greenhouse effect). Therefore, it is urgent to develop advanced environmentally friendly and inexpensive energy conversion and storage systems to solve the energy demand. In this field, we are faced with a challenge caused by the gradual depletion of fossil fuels. To secure a safe and sustainable energy supply, renewable energies such as solar and wind have been developed. However, these energies are limited and intermittent, but rechargeable batteries are the most promising candidates to meet these needs thanks to their high energy density and high energy efficiency. Among them, the lithium-ion battery (LIB), which is operated based on intercalation mechanism, has played an important role in our society in the past two decades. However, the low energy density of LIB has restricted its application as the energy supplier of next generation. Development of metal–air battery has provided a solution benefitting from its much higher theoretical energy density than that of LIB. In contrast to the closed system of LIB, the metal–air battery are featured with an open cell structure, in which the cathode active material, oxygen, coming from ambient atmosphere. In general, the metal–air battery consists of metal anode, electrolyte, and porous cathode. Metals such as Li, Na, Fe, Zn, etc. can be used as anode materials in metal–air batteries.