Electrochemical performance of aluminium alloy in strong alkaline media by urea and thiourea as inhibitor for aluminium-air batteries

The corrosion, behaviour of aluminium alloy anode was investigated with urea and thiourea in 5 M KOH solution. Measurements were performed under various conditions using chemical (hydrogen gas evolution test) and electrochemical techniques containing Tafel polarization, electrochemical impedance spectroscopy (EIS) and galvanostatic discharge. Also Fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy (AFM) techniques were used to study of corrosion inhibition mechanism and aluminium anode surface morphology. The consequences established that urea and thiourea as additives prevent the corrosion of anode in alkaline electrolyte due to adsorption of their molecules on the aluminium alloy surface. The corrosion inhibition efficiency of aluminium alloy-in 5 M KOH in the presence of 25 mM urea and thiourea was investigated by gas hydrogen evolution method, Tafel polarization and EIS techniques. By data analysis of the above three methods, the corrosion inhibition efficiencies for the aluminium alloy were obtained 51.5, 56.3 and 57.1% for urea and 57.0, 60.8 and 62.9% for thiourea, respectively. Also the anodic utilization of the aluminium alloy anode in electrolyte with urea (85.4%) and thiourea (86.1%) is higher than of aluminium alloy in blank solution (83.5%). It is clear from the results aluminium alloy anode has a good discharge plateau at low potential. Therefore, aluminium alloy presented a good discharge performance in 5 M KOH solution in the presence of additives. The results obtained by Tafel polarization, electrochemical impedance spectroscopy and hydrogen gas evolution test techniques were in acceptable agreement with each other and shows this alloy can used in aluminium-air battery. (C) 2017 Elsevier B.V. All rights reserved.

在5M氢氧化钾溶液中，研究了尿素和硫脲对铝合金阳极腐蚀行为的影响。利用化学方法（析氢试验）以及包含塔菲尔极化、电化学阻抗谱（EIS）和恒电流放电的电化学技术，在不同条件下进行了测量。还使用了傅里叶变换红外光谱（FT - IR）和原子力显微镜（AFM）技术来研究缓蚀机理和铝阳极表面形貌。结果表明，由于尿素和硫脲分子在铝合金表面的吸附，它们作为添加剂可防止碱性电解液中阳极的腐蚀。通过析氢法、塔菲尔极化和EIS技术研究了在25mM尿素和硫脲存在下，铝合金在5M氢氧化钾中的缓蚀效率。通过对上述三种方法的数据进行分析，得到铝合金在尿素存在时的缓蚀效率分别为51.5%、56.3%和57.1%，在硫脲存在时分别为57.0%、60.8%和62.9%。此外，在含尿素（85.4%）和硫脲（86.1%）的电解液中，铝合金阳极的阳极利用率高于空白溶液中的铝合金（83.5%）。从结果可以清楚地看出，铝合金阳极在低电位下具有良好的放电平台。因此，在有添加剂存在的情况下，铝合金在5M氢氧化钾溶液中表现出良好的放电性能。塔菲尔极化、电化学阻抗谱和析氢试验技术所得到的结果相互之间具有可接受的一致性，表明这种合金可用于铝 - 空气电池。（C）2017爱思唯尔有限公司。版权所有。