Printing Al-air batteries on paper for powering disposable printed electronics

A printable Al-air battery is successfully developed for the first time by printing the Al ink and the oxygen reduction ink onto a cellulose paper. Currently, the printable Al-air battery can provide an open-circuit voltage of 1 V, a peak power density of 6.6 mW cm⁻² and a maximum current density of 40 mA cm⁻² when using salt water as the electrolyte. With 6 mg Al, the battery can discharge at 1 mA cm⁻² for almost 6 h, leading to a high specific capacity of 951 mA h g⁻¹. It is found that a moderate concentration of the polymer binder and a high concentration of the carbon support are of great importance to the ink functionality, while the hot-press treatment can dramatically improve the electrode performance and robustness. Finally, screen-printed battery prototypes with a specific electrode pattern are demonstrated for powering a small electric fan and a light-emitting diode. The present printable Al-air battery is a novel type of primary power source with low fabrication cost, high energy density and great environmental friendliness, which is especially suitable for powering various disposable printed electronics in the future.