Extraordinary Corrosion Inhibition of Potassium Stannate and Riboflavin Hybrid Additive on the Al Alloy Anode of Alkaline Al-Air Batteries

Abstract

Al-air batteries (AABs) are regarded as a promising future alternative energy source due to their supposedly high energy density. The corrosion of AABs resulting from the hydrogen evolution corrosion and self-corrosion occurring during their use in alkaline solutions represented a significant obstacle to their development, considerably limiting their commercialization. In this study, we examined the corrosion inhibition efficiency of the hybrid anticorrosive agent composed of potassium stannate (K₂SO₃) and riboflavin (Rib) when used as an addition in the electrolyte of an alkaline AAB. The experimental results demonstrated that the incorporation of the hybrid corrosion inhibitor leads to an anticorrosion inhibition efficiency of 70.2%, an increase in the discharge specific capacity, and specific energy of the entire battery from 913 mAh g⁻¹ and 1023 Wh kg⁻¹ to 2128 mAh g⁻¹ and 2511 Wh kg⁻¹, respectively. The adsorption behavior of the additives on the surface of the Al alloy was studied using surface characterization techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). It revealed that the incorporation of the hybrid additive leads to the formation of a dense and uniform protective layer on the surface of the Al anode during the discharge process. This film effectively prevents direct contact between the alkaline electrolyte and the Al surface, drastically reducing the formation of possible hydrogen interactions between the electrolyte and the anode. Consequently, the hydrogen evolution reaction (HER) is efficiently inhibited, and the overall performance of the AAB is improved. Thus, this electrolyte regulation strategy presents a novel approach to studying high-efficiency alkaline AABs.