Multi-center corrosion inhibition strategy for enhanced interfacial stability and longevity of aluminum-air batteries

Aluminum-Air batteries (AABs) suffer from anode self-corrosion and parasitic hydrogen generation. These issues markedly degrade their electrochemical performance. We introduce a novel multi-center adsorption corrosion inhibitor, 2-mercapto-3-pyridinecarboxylic acid (MPA), to mitigate these issues. Theoretical calculations reveal that MPA exhibits an adsorption energy of 1.54 eV on the Al surface, 2.5 times higher than that of H₂O. This high adsorption originates from the multi-center adsorption of its sulfhydryl (-SH), carboxyl (-COOH), and pyridine groups. Experimental results demonstrate that adding 10 mM MPA to 4 M NaOH electrolyte reduces the corrosion current density by 46.1 % (from 25.37 to 13.68 mA cm⁻²) and suppresses the hydrogen evolution rate by 41.7 %. In-situ Fourier Transform infrared spectroscopy (FTIR), and Time-of-Flight secondary ion mass spectrometry (TOF-SIMS) analyses confirm that MPA forms a dense protective layer on the Al surface via Al-S/O/N chemical bonds. This molecular barrier stabilizes the Al anode interface and its kinetic behavior. Compared to traditional corrosion inhibitors, this interface optimization effect of MBA is more significant. As a result, the discharge cycling lifespan of AABs was extended by 1.5 times and the specific capacity was increased by 65.7 % (1379.3 mAh g⁻¹). Molecular dynamics(MD) simulations further elucidate MPA's rapid adsorption kinetics and its ability to inhibit water penetration at the Al interface. Our findings suggest a robust multi-center adsorption strategy that enables the practical development of long-lasting, high-performance Aluminum-Air batteries to develop their commercial application.