Effects of flocculant and corrosion inhibitor compounding on the electrochemical corrosion behavior of the anode in Al-air batteries

To solve the problem of precipitates affecting battery performance in aluminum-air batteries. This study employed a variety of techniques—including flocculant-simulated sedimentation experiments, electrochemical assays, constant current discharge tests, and microscopic morphology assessments—to evaluate the synergistic effects of corrosion inhibitors and flocculants in the electrolyte of aluminum-air batteries. The inorganic polymer compound polyalumi rlillm sulfate (PSA) and the inorganic compound aluminum sulfate were investigated in a 4 mol/L NaOH+0.06 mol/L Na2SnO3 solution to elucidate the electrochemical corrosion mechanism of the 5052 aluminum alloy anode, as well as the sedimentation time and effect of colloidal precipitation. The results showed that the compounding of the two flocculants with the conventional corrosion inhibitor Na2SnO3 enhanced both the sedimentation rate of aluminum hydroxide in alkaline media and decreased the corrosion rate of the aluminum anode. Specifically, 3 g/L PSA was found to be most efficacious, elevating the sedimentation efficiency by 70.6%. Additionally, 1 g/L PSA demonstrated the most significant inhibitory effect on the self-corrosion of 5052 aluminum alloy, leading to an increase in the anode battery's capacity density by 15.5–35.1%. The synergistic action of flocculants and corrosion inhibitors chiefly accelerated the sedimentation rate of precipitates, maintained electrolyte conductivity, and facilitated the formation of a protective film on the surface of the aluminum anode to reduce the self-corrosion rate of aluminum, thereby promoting the improvement of discharge performance of aluminum-air batteries.