Building high-performance aluminum-air batteries:Maltitol-Specific adsorption for suppressing hydrogen evolution reaction

Abstract

Aluminum-air batteries (AABs) have a relatively high theoretical energy density, but the corrosion induced by hydrogen evolution reaction (HER) in the alkaline electrolyte greatly limits their future development. In this study, a corrosion inhibitor maltitol (Mal) is applied and its corrosion inhibition and battery performance are investigated by experimental and theoretical methods. Experimental data demonstrate that the addition of 1.5 M Mal significantly reduces the anodic corrosion current density from 22.3 mA cm⁻² to 7.59 mA cm⁻², signifying a substantial inhibition of corrosion processes. The capacity and energy densities are 2469.1 mAh g⁻¹ and 2469.1 Wh kg⁻¹, compared to 1282.1 mAh g⁻¹ and 1602.6 Wh kg⁻¹ in the Blank group (4 M NaOH). Furthermore, the anode utilization of AABs increases from 43.05 % to 82.92 %. Molecular dynamics (MD) and density functional theory (DFT) calculations demonstrate that the Mal molecule adsorbs onto the Al surface via its hydroxyl(-OH)-terminated side, while its glycosidic side adsorbs H₂O molecules, forming a stable hydrogen-bond (H-bonds) network. This study clarifies the influence of special structure-activity of Mal on the performance of AABs, providing a new strategy for the design of high-performance electrolyte for AABs.