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

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