Screen-printed water-in-salt Al ion battery for wearable electronics

Abstract

Metal ion batteries with “water-in-salt” electrolyte are well known for their low cost and high safety, which are especially suitable for powering wearable electronics. Among them, the Al ion battery holds a great advantage in metal abundance and energy density, which has also been proved reliable with the “water-in-salt” electrolyte system. To facilitate its efficient manufacturing, screen-printing is adopted to develop a “water-in-salt” Al ion battery for the first time. Both the Al anode ink and the graphite cathode ink are prepared and printed onto opposite sides of a cellulose paper, while the “water-in-salt” AlCl3 electrolyte is stored inside the paper by an absorption-evaporation process. Specifically, three anode printing configurations are compared, whose effect on battery performance and durability is studied comprehensively. In general, the battery prototype can sustain a high specific current of 1.0 A g−1 and specific capacity of 120 mAh g−1. A satisfactory lifetime of 550 cycles is also achievable at a lower specific current of 0.25 A g−1. Moreover, this battery can tolerate repetitive bending of 1000 times and even the puncture of its electrodes, proving its great flexibility, robustness and safety for wearable applications. The monolithic battery pack printing is also demonstrated successfully in the end.