Study On The Properties Of Al-Sn-Ga-Bi-Ce Alloy Anode For Aluminum-air Battery

Aluminum-air battery is a new type of green battery with advantages of non-toxic and pollution-free,abundant raw materials,low price and high energy density.Therefore,it has high research value and broad application prospect.Aluminum-air battery electrolyte is alkaline electrolyte,and the anode material is aluminum-based alloy.Because of the aluminum surface tends to form a dense oxide film,which can inhibit the electrochemical activity of anode materials.Meanwhile,it will greatly reduce the overall performance of the battery with the aluminum component of the anode material prone to hydrogen evolution reaction causing corroded seriously.Therefore,how to improve the performance of anode materials is one of the focuses of aluminum-air batteries.In this paper,Bi and Ce elements are added to improve their electrochemical activity and corrosion resistance basing on Al-0.1 Sn-0.1 Ga alloy,and Al-Sn-Ga-Bi-Ce alloy with better performance is obtained.The influence of the amount of Bi and Ce on the structure and properties of aluminum alloy anode and the effect of electrolyte additives on the performance of aluminum alloy anode after optimization are investigated.In addition,due to the introduction of a small amount of impurity iron into the anode material,the corrosion rate of the anode will be increased.Therefore,in order to reduce the harm of impurity iron,B2O3 is added to the molten aluminum to remove iron,and its iron removal effect is also studied.The microstructure and corrosion morphology of the alloy are observed by scanning electron microscope(SEM).The self corrosion rate of the alloy is measured by weightlessness method,and the electrochemical performance of the alloy is studied by electrochemical test.The results show that the electrochemical properties and corrosion resistance of the alloy are improved by the addition of Bi.Al-0.1Sn-0.1Ga-0.1Bi alloy has the best comprehensive properties,when the content of Bi is 0.1%.In 4 mol/L KOH solution,the corrosion morphology of the alloy is uniform and the corrosion rate is 0.29 mg·cm-1min-1;the open circuit potential is-1.461 V(vs.HgO/Hg).When the current density is 100 mA·cm-2,The corrosion current density is 21.0 mA·cm-2;the constant current discharge potential is-1.467 V(vs.HgO/Hg).The EIS of Al-0.1Sn-0.1Ga-xBi alloys have smaller high frequency capacitive arcs,which shows the activation of alloys has been enhanced.The Ce element is added to the Al-0.1Sn-0.1Ga-0.1Bi alloy.The comprehensive properties of Al-0.1Sn-0.1Ga-0.1Bi-0.3Ce alloy are the best when the content of Ce is 0.3%.The self corrsion rate is the smallest about 0.276 mg·cm-2 ·min-1 and the corrosion morphology is uniform;the open circuit potential is shifted to-1.542 V(vs.HgO/Hg)and the corrosion current density is 16.5 mA·cm-2;When the current density is 100 mA·cm-2,the constant current discharge potential-1.551 V(vs.HgO/Hg).The charge transfer resistance Rt and electrochemical diffusion resistance Rc obtained by EIS are reduced,and the alloy activity is improved.In 4 mol/L KOH methanol water solution,with methanol content increasing,the corrosion resistance of the alloy will increased.However,due to the open circuit potential and constant current discharge voltage of the alloy are positive,the electrochemical activity is decreased.When the amount of methanol is 80%,the corrosion rate is 0.048 mg·cm-2·min-1 and the corrosion morphology is uniform.The corrosion current density is 4.10 mA·cm-2,and the corrosion resistance is the best The addition of ZnO additive to 4 mol/L KOH methanol-60%aqueous solution can also inhibit the corrosion reaction of aluminum alloy.When the concentration of ZnO is 0.20 mol/L,the corrosion inhibition effect is better.Similarly,ZnO reduces the electrochemical activity of aluminum alloy anode and the discharge stability.Therefore,ZnO is an inhibitor of anodic inhibition.After adding B2O3 into the molten aluminum,the impurity iron content decreased from 0.17%to 0.15%;the corrosion rate of aluminum decreased from 0.811 mg·cm-2·min-2 to 0.600 mg·cm-2·min-1;the corrosion current density decreased from 40.1 mA·cm-2 to 35.5 mA·cm-2,and the corrosion resistance is enhanced.The open-circuit potential is shifting about 25 mV,and the charge transfer resistance Rt obtained by EIS becomes larger and the electrochemical activity decreases.