Synergistic construction of bifunctional interface film on anode via a novel hybrid additive for enhanced alkaline Al-air battery performance

• Bifunctional interface film is synergistically constructed on Al anode by a novel hybrid additive. • The film activates the Al anode while inhibiting its self-corrosion in alkaline electrolyte. • Experiments and DFT reveal the film-forming mechanism of “site-directed bridging”. • Alkaline Al-air battery exhibits superior performance with hybrid AHMP/ZnO additives. Aluminum-air battery is considered to be a hopeful source of clean energy. However, the serious self-corrosion of Al anode hinders its commercial application. Herein, we propose an original hybrid additive consisting of 4-amino-6-hydroxy-2-mercapto (AHMP) and zinc oxide (ZnO) to inhibit self-corrosion of Al-6061 in alkaline Al-air battery. It induces a dense bifunctional film formed on the anode. The anode utilization rate reaches 60%, and the mass capacity of full cell increases from 879 mAh g -1 (blank) to 1785 mAh g -1 (with the hybrid additive). Surprisingly, this film simultaneously functions to activate the anode, boosting the discharge voltage of full cell. Experiments and theoretical calculations jointly reveal the mechanism formation of this unique bifunctional interface film: “site-directed bridging” of double metals (Al, Zn) to distinct adsorption sites on AHMP molecules. Our work investigates the origin of the synergistic effect for hybrid additives and provides a new strategy for screening functionalized additives to construct characteristic aluminum/electrolyte interface film for Al-air battery.