Addressing Transport Issues in Non-Aqueous Li-air Batteries to Achieving High Electrochemical Performance

Li-air batteries are a promising type of energy storage technology because of the ultra-high theoretical specific energy. Great advances are made in recent years, including the illustration of reaction mechanisms, development of effective catalyst materials, and design of battery structures accelerating species transport. However, the application still suffers from low rate capability, poor round-trip efficiency, and unsatisfactory cycling life. Herein, we mainly focus on the species transport issues of non-aqueous Li-air batteries, including -Li+ across the solid surfaces and the electrolyte, O-2 solubility and diffusivity, distribution of intermediates and products, and side reactions by other components from the air. Besides, considerable emphasis is paid to expound the approaches for enhancing species transport and accelerating reactions, among which the realization of well-designed electrode structures and flowing electrolytes is of great significance for the rapid migration of O-2 and -Li+ and mitigating the negative effects by solid insoluble -Li2O2. Moreover, optimizing reaction interfaces and operating conditions is an attractive alternative to promote reaction rates. This work aims to identify the mechanism of transport issues and corresponding challenges and perspectives, guiding the structure design and material selection to achieve high-performance Li-air batteries.