High Performance Al-Air Batteries (AABs) with Reduced Corrosion

Abstract

Al-air batteries (AABs) are candidates for next-generation energy storage devices owing to their high energy density, low cost and eco-friendliness. While most AABs use alkaline electrolytes because of the high discharge voltage and high solubility for discharge products, the corrosion of Al anode in the alkaline electrolyte is inevitable. This reaction consumes Al and generates heat and H2 gas, hindering the practical usage of AABs. The traditional methods for alleviating this problem are alloying Al anode and adding corrosion inhibitors into electrolytes. The inhibitors can form a protection layer (PL) composed of metallic or organic deposits on the surface of the Al anode. The metals with high H2 evolution overpotential can change the corrosion potential of Al anode when it is alloyed into or deposited onto Al anode, which in turn reduces the corrosion.Over the years, researchers have put much effort into finding a better combination of alloying metals and inhibitors to get higher Al anode utility, but the corrosion inhibition performance has not been improved for a long time. If the corrosion problem was restrained, the high energy densities make AABs promising to be applied in electric vehicles and many other fields. Herein, a stabilizing layer (SL) was introduced to increase the stability of PL. By stabilizing the PL through elastic force from SL, the PL becomes denser and the corrosion reaction of the Al anode could be further diminished.The tested Tafel curves reveal that the corrosion rate of Al anode was decreased with the support from SLs. SEM and XRD characterizations were also made to verify that the PL was stabilized by SLs. Besides, different SLs were compared to identify influence of the ion diffusion ability of SLs on the performance of batteries, showing SLs result in significant reduced corrosion. The batteries using SLs offer useful insights into the effect of PL formed by the inorganic inhibitors in the electrolyte, and provide a new way to improve AABs which makes it more attractive technology.