The efficient acetoxy-group-based additives in protecting of anode in the rechargeable aluminium-air batteries.

The inhibitive effects of functional groups originating from the presence of additives on corrosion are linked to the physicochemical and electronic properties of these surficial chemical species. In this work, the acetoxy group (i.e. weak bases) with different orbital characters is integrated with donating/accepting molecules which reveals dissimilar inhibitive behaviour. Introducing cations on the acetoxy groups (-Ac) as additives leads to mitigation of undesirable self-corrosion of the anode. The Al-air battery corresponded to a maximum capacity of 2817 mAhg−1 at 10 mAcm−2 with the use of barium-Ac/KOH electrolyte, demonstrates nearly 95% of the theoretical capacity. However, a capacity of only 2392 mAhg−1 is observed for free additive. In addition, the maximum power density (i.e. 91.32 mWcm−2) increased by nearly 50% with the employment of barium-Ac/KOH. The rechargeable Al–air battery based on barium-Ac/KOH presents a low voltage gap of 0.83 V with a remarkable cyclic stability of 25,000 s. The results show that the acetoxy group integrated with metal ions can be a key player in reducing H 2 evolution rate in the aluminium-air batteries. XPS analysis confirmed an Al-complex (i.e. Al-acetoxy) is formed using barium-ac. DFT calculations confirmed that barium-Ac/KOH provides the minimum value of ΔE (about 5.4 eV), indicating the remarkable ability for reacting with Al+3 ions to adsorb on the anode surface leading to complex (Ba-Ac-Al3+) formation. This study highlights the parasitic corrosion reaction leading to low coulombic efficiency in rechargeable Al- air batteries. • The impacts of additive integrated with acetoxy group was studied on Al corrosion and H2 evolution. • The corrosion inhibition efficiency follows the order of: Ba-acetoxy > Ca-acetoxy > Ethyl-acetoxy. • Ba–Ac/KOH exhibited the optimum discharge capacity 2817 mAh/g and 95% Al utilization. • XPS results revealed a complex containing Al-acetoxy contribute to reduce Al self-corrosion. [ABSTRACT FROM AUTHOR]