Effect of barbituric acid in regulating the Al anode/electrolyte interface layer for Al-air batteries in alkaline medium

This study investigates the effectiveness of barbituric acid (BA) as an additive for pure aluminum (Al) anodes to enhance the performance of aluminium-air batteries. Various concentrations of BA are incorporated into a 4M NaOH alkaline electrolyte, and their impact is evaluated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and galvanostatic discharge testing. EIS results reveal that at 2 wt% BA, the corrosion protection efficiency reaches 53.19 %. Surface characterization techniques, including surface morphology analysis, contact angle measurement, atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR), confirm the adsorption of BA on the aluminum surface and the formation of a protective film. The addition of BA significantly reduces the corrosion rate and enhances electrochemical performance. Notably, the specific capacity increases from 1219 mAh·g⁻¹ (40.95 % utilization) to 2000 mAh·g⁻¹ (67.16 % utilization) at 2 wt% BA. However, at 2.5 wt% BA, a slight reduction in energy density and anodic utilization is observed, likely due to excessive surface adsorption affecting ion transport. These findings highlight both the benefits and limitations of BA as a corrosion inhibitor in aluminium-air battery systems.