Improvement of Electrochemical Performance with Cetylpyridinium Chloride for the Al Anode of Alkaline Al-Air Batteries

Aluminum-air batteries (AABs) are considered among high-power battery systems with various potential applications. However, the strong self-corrosion of Al in alkaline electrolytes negatively affects its Coulombic efficiency and significantly limits their large-scale application. This work presents the use of cetylpyridinium chloride (CPC) as an inexpensive and environmentally benign electrolyte additive in alkaline AABs. Hydrogen evolution test, electrochemical measurement, and surface analysis techniques were used to investigate the inhibition effects of CPC additive for the Al anode. The potentiodynamic polarization data indicated that the effectiveness of the CPC in inhibiting corrosion increased proportionally with higher CPC concentration. The maximum inhibition efficiency of 53.6% was achieved at a CPC dosage of 5 mM. The hydrogen evolution experiment revealed that the rate of hydrogen evolution decreased from 0.789 mL cm^-2 min^-1 for the pristine NaOH solution to 0.415 mL cm^-2 min^-1. The combination of X-ray photoelectron spectroscopy (XPS) and <i>ab initio</i> molecular dynamics (AIMD) provides conclusive evidence that CPC may adhere to the surface of Al and create a protective film. These findings indicate that CPC is successful in preventing the self-corrosion of the Al anode. Additionally, the Al anode has improved electrochemical characteristics, including a high specific capacity of 2041 mAh g^-1 and a high energy density of 2874 Wh kg^-1. This work focuses on the inhibition of self-corrosion of Al and provides novel insights for the design and development of effective additives for AABs.