A Polyurethane Organic Framework for Flexible Al-Air Batteries

Flexible Al-air batteries with hydrogels are regarded as a promising power source owing to their high specific capacity, their high ionic conductivity, and having no leakage. However, the mechanical properties of the hydrogels remain unresolved. Here, we present a polyurethane organic framework (POF) employing a polyurethane skeleton as an internal support for poly(acrylic acid) (PAA) hydrogel, where the POF can exhibit high strength and toughness, and an Al-air battery using the POF can output good electrochemical properties. The results demonstrate that the tensile stress of 30 ppi POF is 49.5 kPa owing to the stress-transfer mechanism, while that of PAA is only 3.1 kPa. Compared to that of the PAA hydrogel, the discharging capacity of Al-air batteries with 20 ppi POF can be increased by 79 mAh cm^-2at a current density of 1 mA cm^-2, which can be attributed to corrosion inhibition and the surface roughness change of the POF during the discharging process. This work will deliver a selectable strategy for a trade-off between mechanical and electrochemical properties.