Inhibition effect and mechanism of inorganic-organic hybrid additives on three-dimension porous aluminum foam in alkaline Al-air battery

The main barrier preventing the commercial application of alkaline aluminum-air battery is the severe self-corrosion of Al anode. Herein, three kinds of novel inorganic-organic hybrid corrosion inhibitors are constructed, which containing ZnO and organic acids (acetic acid, citric acid and EDTA). Electrochemical tests demonstrate that the combination of ZnO and organic acid effectively suppresses the self-corrosion of Al foam anode In alkaline solution. Among them, the Al-air battery exhibits a high voltage platform (1.13 V), a high specific capacity (1902 mA h g(-1)) and a high anode utilization (58.23%) within 0.3 M ZnO+0.03 M citric acid hybrid inhibitors system. Surface analyses confirm that the organic acid greatly boosts the formation of uniform and dense Zn film on Al surface. A combined experimental research and theory computation reveal that the corrosion inhibition mechanism of ZnO + organic acid hybrid system is: the phase-forming corrosion inhibitor (ZnO) deposit on the Al surface to form Zn protective film and cover the active sites of hydrogen evolution; the active sites of organic acids are the O atoms of carbonyl groups, which adsorbing on the surface of Zn protective film and Al foam, thereby forming the composite protective films of RCOO-Al and RCOO-Zn.