The role of SO-group-based additives in improving the rechargeable aluminium-air batteries.

The influence of various sulphur-oxygen (SO) group additives has been investigated in retarding the self-corrosion of Al anode in a 4M KOH solution, in order to effectively enhance the overall performance. The studied additives in this work were all found to be capable of decreasing H 2 evolution, and could mitigate aluminium self-corrosion, with the corrosion inhibition towards the cathodic protection process. The less pitting corrosion and holes were observed for inorganic additives in comparison to the organic counterparts. The Al-air batteries demonstrated an improvement in the discharge capacities: 2604, 2393, 2348 and 2048 mAh g−1 for Na 2 SO 4 , Na 2 SO 3 , C 2 H 6 SO, and C 6 H 5 SO 2 OH, respectively, in comparison to that associated with the 4M KOH (2021 mAh g−1). K 2 S 2 O 8 , an inorganic additive, exhibited a hydrogen evolution efficiency of 21%, but the lowest discharge performance (1973 mAh g−1). This may be due to the instability of the anions in redox reactions. The low inhibition efficiency of the hybrid additives in Al self-corrosion, when compared to single additives, may be ascribed to the involvement of Al3+ in complex formation of the inorganic-organic hybrid additives. A stable discharge-charge cycling test over 6 h with a voltage gap of around 0.7 V is observed for Na 2 SO 4 , demonstrating the efficient performance compared to the additive-free KOH electrolyte. It could be concluded that efficient additives containing SO group, successfully mitigated the self-corrosion and hydrogen evolution associated with the Al anode that was confirmed with DFT results. [ABSTRACT FROM AUTHOR]