Abstract: In this study, N-acetyl-DL-tryptophan (NDLT), an amino acid derivative, was introduced as an electrolyte additive to regulate the anode behavior of alkaline aluminum-air batteries (AABs). The effect mechanism of NDLT on Al alloy anode was systematically investigated through hydrogen evolution measurements, electrochemical tests, full-cell performance evaluation, and microstructural characterization. The results demonstrate that NDLT can adsorb onto the Al alloy surface to form a compact water-blocking protective layer, effectively preventing direct contact between water molecules and the Al surface. This adsorption behavior significantly suppresses Al self-corrosion and parasitic hydrogen evolution reactions (HER), thereby improving the discharge performance of AABs. Meanwhile, NDLT contributes to the construction of a uniform and stable Al/electrolyte interface, leading to an enhanced discharge potential and improved electrochemical kinetics of the Al anode. In a 4 M NaOH electrolyte, the optimal inhibition concentration of NDLT was determined to be 7 mM, at which the Al anode utilization reached 88.3%. Full-cell tests further revealed that the introduction of 7 mM NDLT increased the energy density from 1550 Wh kg?1 to 3448 Wh kg?1 and the capacity density from 1324.9 mAh g?1 to 2632.3 mAh g?1. This work provides an effective and environmentally benign electrolyte regulation strategy to enhance the durability and energy output of alkaline AABs, and offers a theoretical basis for the design and development of high-efficiency amino acid-derived additives.

Key words: Aluminum-air battery, Interface regulation, Electrolyte additive, Amino acid derivative