Regulating H-bonded network of aqueous electrolytes for stable and energy-dense Al-air batteries

Abstract

Aluminum-air batteries offer unique advantages over other aqueous batteries in terms of environmental friendliness, energy density, resource abundance, and cost-effectiveness. Nevertheless, the parasitic hydrogen evolution reaction (HER) of anode presents severe challenges for stable and long-term operation of batteries. Here we found that the mixed solution with strong H-bond network has a significant inhibitory effect on the self-discharge and HER of Al anode in alkaline electrolyte. And establishing the relationship between the molecular structure of the cosolvent (carbon chain lengths and hydrogen bond acceptors) and the strength of the hydrogen bonding network of the electrolyte. The as-constructed Al-air battery with ethylene glycol (EG) cosolvent demonstrates a remarkable increased discharge specific capacity of 2725 mAh g^-1, corresponding to the Al anode utilization of 91.4 %. The operation time also extends to 160 h at 5 mA cm^-2. This work provides new avenues to understand the role of H₂O in aqueous electrolytes and explore low-cost and effective approaches for the development of next-generation aqueous Al-air batteries.