Al-air batteries are an attractive power source for next-generation electronics due to their high theoretical energy density and excellent rate performance. In addition, the raw materials are abundant and relatively low cost compared to rare minerals required for other battery technologies. One of the challenges in realizing the high theoretical energy density is the corrosion of aluminum in alkaline electrolytes, where the consumed anode and hydrogen generation reduce the output voltage and shelf life of Al-air batteries. Although several reports have attempted to optimize the Al-air battery performance and suppress hydrogen formation, the key mechanisms that contribute to Al corrosion are still not fully understood. Our research found that corrosion is closely related to anode impurities and electrolyte components. In this talk, we realize two types of biodegradable double network hydrogels (DNHs) for quasi “solid state" Al-air batteries and show how they reduce anode corrosion and affect battery performance compared to an aqueous electrolye. The DNHs are stretchable and have high conductivity that allow for a high power density.  In addition, their polymer network structure affects the uniformity of electrochemical reactions and corrosion, which we compare acrosss multiple grades of Al anodes (Al alloy and 5N) with optical microscopy, electron microscopy, and electrochemical methods. The Al-air battery with DNHs could achieve a 410% increase in usable area energy density and 150 mV decrease of Al anode comparing to the one with aqueous electrolyte. DNHs lowers the self-corrosion of Al by 5% per hour and enables the cell with a high capacity of 320 mAh per square center meter. Finally, we will come up with an optimized strategy for future Al-air batteries with high capacity.

Biodegradable double network hydrogels for high capacity Al-air batteries with suppressed corrosion

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ACS Fall 2022

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