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–2 at 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.