Corrosion inhibition of polyelectrolytes to the Al anode in Al-air battery: A comparative study of functional group effect

Al-air battery is a promising alternative to electrochemical storage systems because of their high energy density and low cost. However, the hydrogen evolution corrosion in alkaline electrolytes is a major obstacle before this technology can be commercially viable. In this paper, three polyelectrolytes as corrosion inhibitors for pure Al anodes in KOH electrolytes are investigated by electrochemical methods, hydrogen evolution rate (HER) tests, weight loss measurements, and surface characterization. The Attenuated Total internal Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) and theoretical simulation results show that all the polyelectrolytes can be adsorbed on Al to form a protective barrier against the corrosive species. In particular, poly(allylamine) (PAH) exhibits the highest corrosion inhibition efficiency. Furthermore, galvanostatic discharge measurement reveals that the Al-air battery in PAH electrolyte exhibits the highest specific discharge capacity (1495.2 mA h g−1). Computational analysis shows that the inhibition performance depends on the frontier molecular orbital energy and adsorption energy.