Abstract:The effects of 8-hydroxyquinoline on the corrosion and discharge performance of AP65 magnesium alloy as anode for Mg-air battery were studied by the mass loss test, electrochemical measurements and corrosion product analysis. The results show that the addition of 8-HQ in 3.5%NaCl (mass fraction) solution decreases the corrosion rate of AP65 alloys from (0.36±0.1) mg·cm²/h to (0.028±0.0.5) mg·cm²/h, shifts the corrosion potential to the positive direction, and decreases the corrosion current density from (46.95±3.3) μA/cm²to (18.37±4.8) μA/cm². When being assembled as single Mg-air battery and discharged at a current density of 2 mA/cm², AP65 alloys express an improved current efficiency from 21.4% to 62.4% with the addition of 8-hydroxyquinoline into 3.5% NaCl solution. When being discharged at a current density of 15 mA/cm², the discharge voltage of single Mg-air battery increases from 0.89 V to 0.96 V with the addition of 8-hydroxyquinoline. The discharge products of AP65 magnesium alloy in 3.5% NaCl electrolyte containing 8-hydroxyquinoline are mainly Mg(HQ)₂ and Mg(OH)₂. The thin and uniform corrosion film is beneficial to the penetration of Cl^- ion. Meanwhile, PbO₂ compound is deposited between the corrosion film and the substrate. It can peel off the corrosion product and enhance the comprehensive activation dissolution as well as the discharge activity of AP65 alloy matrix.

Key words: Mg-air battery; AP65 magnesium alloy; self-corrosion; 8-hydroxyquinoline