F⁻ competitive attack decomposing parasitic product Al(OH)₃ of hydrogel-based Al-air battery

Wearable Al-air batteries are regarded as the potential power systems for flexible electronics due to the ultra-high capacity and energy density of Al-based materials. However, the battery failure caused by the accumulation of parasitic product Al(OH)₃ upon the anode surface has hindered the commercialization. Herein, we report a polyacrylic acid hydrogel integrating KF and KOH (F@PAA), which decompose Al(OH)₃ for ameliorating discharge performance of wearable Al-air battery. The ions channels upon the anode surface are dredged by a competitive attack of F⁻ on Al-O, thus improving the battery durability. The results show that the binding of Al³⁺ with F⁻ is more stable than that with O²⁻. The formed complex AlF₆³⁻ corrodes the passivation layer, and then ensures the continuous anodic oxidation. When 1.0 M F⁻ is introduced into F@PAA hydrogel, the effect of byproduct decomposition and battery discharge are optimal. Hence, A wearable Al-air battery using the proposed hydrogel achieves a maximum power density of 58.28 mW/cm². A high capacity of 2199.10 mAh/g and anode efficiency of 73.80% for the battery can be obtained at 10 mA/cm². Moreover, the key performance of the battery is improved by up to 104.08%, developing interface cleaning technology in wearable Al-air batteries.