![]() ![]() 6–11 Ionic liquids have been used as an electrolyte for aluminum electrodeposition in recent studies. To prevent accumulation of byproducts and corrosion of the anode due to direct contact with the electrolyte while retaining aluminum ion conduction, we coated an aluminum anode and air cathode with a ceramic oxide or carbon materials in our previous studies. 5 However, the above approaches have not led to commercial production of aluminum–air batteries because byproducts such as Al 2O 3 and Al(OH) 3 accumulate at both the anode and cathode. Efforts to suppress this parasitic corrosion include doping of high-purity aluminum (99.999% grade) with specific alloying elements 4 and introducing corrosion inhibitors into its electrolyte. 2,3 A major barrier to commercialization of such batteries, however, is the high rate of aluminum self-corrosion in alkaline solutions both under open-circuit conditions and during discharge. These advantages, as well as its low price-per-energy unit has increased interest in its use as an anode material in battery systems, specifically, in alkaline metal–air batteries. Furthermore, the theoretical specific volumetric capacity of Al is the highest among the metallic fuels (8.04 A h cm 3). Relative to Al, only lithium has a slightly higher electrochemical equivalent (3.86 A h g −1). The low atomic weight (28.98 g mol −1) and trivalence oxidation of Al results in its low gram-equivalent weight (8.99) and ultrahigh specific gravimetric capacity (2.89 A h g −1). 1 Aluminum (Al), the most abundant metal in the Earth's crust, is particularly a highly attractive energy source because of its physical and chemical properties. For these batteries, active metals such as Li, Ca, Mg, Al, Fe, and Zn may be used as anode materials. Introduction Metal–air batteries have attracted attention in electrochemical research and development in the last 50 years because they have specific energies that are much higher than those of most of the available primary and rechargeable batteries such as Li ion, Ni–Cd, and lead–acid batteries. In addition, we did not observe Al(OH) 3 and Al 2O 3 on the anode electrodes, which are byproducts that inhibit aluminum–air battery function. However, the cell capacity, cyclic voltammetry behavior, and cell interfacial impedance was more stable over repeated electrochemical reactions when the MOF was used as an air cathode material. When we used aluminum terephthalate as an air cathode material, the electrical power output and cell capacity were lower than that attained with the cell using activated carbon as air cathode material. We used aluminum terephthalate as a metal–organic framework (MOF) material for the air cathode and 1-ethyl-3-methylimidazolium chloride as an ionic liquid electrolyte. The goal of this study was to develop a rechargeable aluminum–air battery with high capacity and long-term durability in charge–discharge electrochemical reactions. ![]()
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