The Study On Aluminium Electrode And Electrolyte In Aluminium-Air Battery

The aluminium-air battery is greatly concerned because of its higher energy and lower price. However, it has not been widely used partly due to such problem as corrosion and passivation, which make it difficult for the alkaline battery properties to satisfy the practice. Therefore, it would be of important theoretical significance and practical value to study the mechanism of aluminium anode and the effect of various additives on electrochemical property of aluminium in alkaline solution .The first work of this thesis is to probe for laws of Rt(charge trassfer resistance) and passivation film's thickniss in 4mol/L KOH at different potential by AC impedance. It has also been found that Rt decreases with increase of impurities(Fe,Cu and Si) in aluminium, whereas corrosion current density (Jcorr) increases. Secondly, effects of additives(such as Na2SnO3,HgCl2 (HgO),K2MnO4) on electrochemical properties of Al in 4mol/L KOH were studied by using Tafel curves, AC impedance, linear scan volt- ammary and constant-current discharge curves. The main conclusion may be summarized as following: (1) To some extent, electrochemical properties of Al are also improved by use of above three kinds of additives; (2) Activity of Al and inhibition efficiency are excellent in additives HgCl2; ordinary in additives Na2SnO3, poor in K2MnO4; (3)The optinium concentration of additives is 5mmol/LNa2SnO3, 0.05mmo/L HgCl2 and 0.8mmol/L K2MnO4. Then, it is proved that the effect of NaAlO2 on the electrochemical property of aluminium is disadvantageous; but it has been shown that passivation of Al decreases, that potential moves from positive to negative, and that lag-time of potential is shortened when 50mmol/L NaF is added into '3.5mmol/L NaAlO2 +4mmol/L KOH'.At last, experiments are carried out to explore the effects of two kinds of gelled electrolytes(4mol/L KOH added by CMC and polyacrylic-acid) on electrochemical properties of Al. It has been found that electrochemical properties of Al in '2.5% polyacrylic-acid+4mol/L KOH' are better than in 'CMC+4mol/L KOH', that proper- ties of Al are also improved by adding '5mmol/L Na2SnO3, 0.05mmol/L HgCl2 and 0.8mmol/L K2MnO4' into'2.5% polyacrylic-acid+4mol/L KOH'respectively;Na2SnO3 is best; second in K2MnO4.