High-Performance and Recyclable Al-Air Coin Cells Based on Eco-friendly Chitosan Hydrogel Membranes

Aluminum-air batteries are a promising power supply for electronics due to their low cost and high energy density. However, portable coin-type Al-air batteries operating under ambient air condition for small electronic appliances have rarely been reported. Herein, coin cell-type Al-air batteries using cost-effective and eco-friendly chitosan hydrogel membranes modified by SiO₂, SnO₂, and ZnO have been prepared and assembled. The Al-air coin cell employing chitosan hydrogel membrane containing 10 wt % SiO₂ as a separator exhibits better discharge performance with a higher flat voltage plateau, longer discharge duration, and higher power density than the cells using a chitosan hydrogel membrane containing SnO₂ or ZnO. Moreover, we also demonstrate that the presented Al-air coin cell can be recycled by a series of eco-friendly procedures using food-grade ingredients, resulting in recycled products that are environmentally safe and ready for reuse. The Al-air coin cell adopting a recycled cathode from a fully discharged Al-air coin cell using the above-mentioned procedure has shown comparable performance to cells assembled with a new cathode. With these merits of enhanced electrochemical performance and recyclability, this new Al-air coin cell with modified chitosan hydrogel membrane can find wide applications for powering portable and small-size electronics.