A flexible, electrochromic, rechargeable Zn//PPy battery with a short circuit chromatic warning function

A rechargeable battery with both flexibility and electrochromism integrated into a single apparatus is a major component for smart flexible electronics. However, suitable electrode materials with electrochromic properties are still being searched for. Here, for the first time to the best of our knowledge, we realize a flexible, electrochromic and rechargeable battery by successfully matching electrochromic polypyrrole (PPy, as cathode) with zinc (Zn, as anode). The fabricated rechargeable Zn//PPy battery delivers a high capacity of 123 mA h gPPy−1. It possesses flexibility and an electrochromic capability of turning from black to yellow when the voltage changes from 1.2 to 0 V. Therefore, the battery exhibits a unique function of a short circuit chromatic warning which turns yellow at 0 V. Our battery, uniquely combined with these multiple smart features, represents solid progress in smart flexible electronics.