A flexible electrochromic device is disclosed, the device including a flexible substrate with at least one electrically conductive surface, and an adhesive ion-conducting layer including a) a polymer binder selected from the group of polyvinylpyrrolidone and copolymers of vinylpyrrolidone, and b) a source of mobile cations, e.g., alkali metal salts, acids, polyelectrolytes and polyacids, wherein the device is capable of being deformed and returned to "flatness" in an undamaged state.