Photo-assisted Al-air batteries based on gel-state electrolyte

The use of new concept electrochemical devices to store and release solar energy has always been a research hotspot in the society of resource shortage. In this work, we firstly introduce sunlight into the Al-air battery by CuO and Cu2O semiconductor electrode materials to improve the discharge voltage under illumination and the calcium alginate hydrogel-based electrolyte is also applied to the Al-air battery. The calcium alginate hydrogel-based electrolyte can greatly inhibit the self-corrosion of aluminum, resulting in the specific capacity of Al-air battery being significantly increased. At the current density of 1 mA cm−2, the CuO air cathode shows better performance, the maximum discharge voltage is 1.37 V and 1.23 V under illumination in aqueous sodium hydroxide solution and hydrogel, respectively, while the maximum discharge is 0.9 V and 0.78 V in the darkness. And the specific capacity in the hydrogel is about 20 times that of the aqueous sodium hydroxide solution. In addition, the semiconductor energy band structure and the discharge mechanism of the photo-assisted Al-air battery under illumination are also studied. This study provides a prospect for the conversion and application of solar energy in the photo-assisted Al-air battery.