A New Type of Flexible Energy Harvesting Device Working with Micro Water Droplet Achieves High Output

Aluminum is one of the most promising candidates for metal-air battery due to its abundance, high specific energy and theoretical voltage. However, Al-air battery is hindered by high corrosion rate in aqueous alkaline solution. In this work, a new type of hybrid device is presented which combines sandwich-like hydrocapacitor and Al-air battery together using a common polyaniline composite/carbon nanotube (PANI/CNT) electrode. This device achieves all-solid-state without adding electrolyte in advance which could reduce corrosion greatly, control the initiation and cessation of reactions, and prevent harmful leakage or deformation of electrolyte completely when it is not used. It could provide a maximum open-circuit voltage of 1.5 V within one minute after adding only a drop of tap water instead of using alkaline and saline electrolyte and maintain over 1 V for more than 3 hours. When another drop of tap water was added, it could start working again. Moreover, daily measurement of the open-circuit voltage of the same device was tested repeatedly for a month and the maximum could all maintain over 1 V which shows circularity and stability. In addition, the integration of the device was also demonstrated using three devices to light up a light-emitting-diode. The performance could still maintain at a great level under bending condition. The working mechanism is also discussed in this work.