Aluminum Corrosion Mitigation in Alkaline Electrolytes By Hybrid Inorganic/Organic Inhibitor System for Power Sources Applications

The changing and expanding needs in the energy market, ranging from power grid energy storage system to portable power sources have necessitated the development of efficient, inexpensive, and high performance battery systems to better deal with the challenges posed by the nascent green economy and non-oil based transport system. One of the promising avenues for achieving these goals is the development of aluminum battery systems based on aluminum and aluminum alloys as anodes. The main advantages presented by this system are rather low equivalent weight of the aluminum, its high natural abundance in the Earth’s crust, its low price, and its safety characteristics; also, it is substantial that aluminum and its byproducts are non-toxic and environmentally friendly. Using aluminum for these applications requires overcoming various obstacles when using different electrolyte solutions. When using aluminum in alkaline based systems the corrosion rate is very high therefore, blemishes its use in alkaline based batteries. High parasitic corrosion rate impairs the functionality of the battery due to capacity lost, dangerous hydrogen generation and significantly shorten its shelf life. Although aluminum alloys can reduce parasitic corrosion, they are frequently complex and rather expensive materials. A promising solution to the undesired corrosion is to use inhibitors which mitigate self-corrosion. Different types of inhibitors are available for use at this time, but none of them mitigate the corrosion of aluminum in alkaline solution to the extent of commercialization of a battery system. In this work, an investigation was performed on the effect of a hybrid organic\inorganic inhibitor, poly(ethylene glycol) di-acid (PEG di-acid) and zinc oxide (ZnO), in a 5M KOH solution. The inhibitors behavior on a pure aluminum was studied electrochemically, microscopically, crystallographically, and element analysis tests were performed. Moreover, the performance of aluminum air cells with alkaline solutions utilizing the hybrid inhibition approach was evaluated by galvanostatic measurements (discharge). The results of our study clearly showed that there is a distinct and strong relation between the mitigation of the corrosion to the presence and concentration of both PEG di-acid and ZnO in the solution.  It was found that with the use of hybrid inhibition approach more than one order of magnitude redaction in corrosion currents and double the capacity of aluminum-air battery were achieved.