Anti‐corrosive additives for alkaline electrolyte in Al‐air batteries: NH₄VO₃ and polyoxometalates

Abstract

Aluminum-air batteries are a promising alternative for portable energy storage. However, one of the significant issues in this technology is the corrosion of aluminum in alkaline electrolytes. In this study, we explored heteropolyacids (HPAs) H 5 PMo 11 Al 0.5 V 0.5 O 40 and H 6 PMo 11 AlO 40 as possible anti-corrosive additives in Al7475, Al6062, and Al5052 commercial alloys. We also investigated the anti-corrosive properties of commercial NH 4 VO 3 and ZnO. Concerning HPAs, only H 6 PMo 11 AlO 40 in combination with Al5052 showed anti-corrosive activity. However, ZnO did not present anti-corrosive properties in Al6062 alloy, while NH 4 VO 3 presented anti-corrosive properties for all three alloys. The combination of carboxymethylcellulose with NH 4 VO 3 further improved the anti-corrosive properties in the Al7475 alloy. We observed by using 2D Raman imaging the formation of polymeric forms of tetrahedral V +5 O 4 over the surface of three alloys. The main conclusion of our studies is that NH 4 VO 3 combined with carboxymethylcellulose is a promising anti-corrosive in the alkaline electrolyte of aluminum-air batteries.

Performance Improvement of Alkaline–Electrolyte Aluminum–Air Batteries by NH4VO3-Based Additives

“…From Figures and , we observe that with liquid electrolyte, ZnO slightly increased the specific capacity and energy of the Al7475 and Al5052 alloys and practically did not affect the Al6062 alloy. This behavior is consistent with our observations in our previous corrosion study …”

“…This behavior is consistent with our observations in our previous corrosion study. 48 A more significant effect was observed for all the alloys in the cells prepared with gelled electrolytes. However, it is crucial to remember that ZnO's concentration was greater in the gel experiments (approximately 0.2 mol L −1 ).…”

“…In a prior study, we evaluated the anticorrosive properties of NH 4 VO 3 and NH 4 VO 3 + CMC additives in Al7475, Al6062, and Al5052 alloys, and we compared them to the extensively used ZnO additive. ,, By hydrogen production experiments, we were able to quantify and compare the anticorrosive properties of these additives. In general, we remarked that the corrosion rate in blank samples without an additive was Al5052 > Al7475 > Al6062.…”

“…Additionally, vanadate compounds are exciting alternatives. They have low toxicity and cathodic inhibitory effects (changes in cathodic mechanism) on Al5052, Al6062, and Al7475 aluminum alloys by forming protective polymeric layers. − In our prior study, NH 4 VO 3 and NH 4 VO 3 + CMC showed anticorrosive potential in commercial aluminum alloys in alkaline medium with the capacity of protection against self-corrosion superior to the traditionally used ZnO additive.…”

Self-assembly of an amino acid derivative as an anode interface layer for advanced alkaline Al–air batteries

“…Inorganic additives containing elements with a high hydrogen overpotential (such as ZnO, CaO, Na 2 SnO 3 , and Sb 2 O 3 ) have been found to effectively inhibit the self-corrosion of the Al anode. 17,18 However, their use is also associated with an increase in anode polarization. Recently, organic additives containing heteroatoms ( e.g.…”