Unravelling the deposition of Zn and Sn as corrosion inhibitor on aluminum (Al) surface for Al-air battery application with sodium chloride electrolytes

Abstract

Recently, Aluminum (Al) has been extensively developed as an anode material for Al-air batteries. High corrosion rate and slow kinetic reactions of Al in anode application drive the recent research to coat with other more noble metals. Therefore, the primary objective of this work is identifying the effect of zinc (Zn) and tin (Sn) coating on high purity Al surface for electrochemical properties improvement. The employed method of metal oxide coating was electrodeposition process. The structural and morphological of electrodeposition was investigated by scanning electron microscopy (SEM). The surface of Zn-Al was finer than Sn–Al. Additionally, the observed cracks on the surface were analyzed and interpreted as indicative of mixed metal oxide (MMO) coating behavior. In electrochemical performance, the Zn–Al half-cell exhibits a consistent open circuit potential value of −0.94 V. This value is the most stable compared with other variables. Remarkably, the discharge time that represents full-cell of Zn–Al and N-doped carbon-based cathode performance was about 14 h, which is nearly fourteen orders compared with Al variables that can only sustain in an hour. The electrodeposition also contributes to enhancing the specific capacity from 40.763 m Ah g−1 to become 324.627 mAh g−1. In line with other measurements, the corrosion rate with linear polarization measurement placed Zn–Al with the smallest corrosion rate, that is 3.71 × 10-5 mm/year. All the electrochemical measurements used 3.5 % NaCl as the model of seawater electrolytes. This finding could be a reliable option of aluminum air battery development on larger scale in the future.