Electrolytes for aluminum-air batteries: advances, challenges, and applications

Aluminum-air batteries (AABs) are attracting increased attention because of their high energy density, low cost, and excellent security. Nonetheless, the commercialization process is hindered by two major hurdles, i.e., anode polarization and self-corrosion. The former impedes the electrochemical reaction, resulting in a large gap between the actual potential and the theoretical value. And the latter will consume the Al anode to produce H-2, which seriously impairs the specific capacity and safety of the battery. Since the electrolyte is a key component connecting the cathode and anode by ion transmission, the regulation of electrolytes is an effective way to ameliorate these two issues. This review summarizes recent progress in the research and development of electrolytes for primary AABs, including aqueous electrolytes, non-aqueous electrolytes and solid-state electrolytes. The working mechanisms and underlying design strategies of different electrolytes are concluded. And then we discuss their advantages and disadvantages, based on which the application prospects of different electrolytes are especially presented to facilitate further research and development of electrolytes for practical AABs.