A new frontier of flexible energy devices: Aqueous proton supercapacitors

Aqueous proton supercapacitors are considered as promising energy storage devices for next-generation wearable electronics due to their high energy density, rapid kinetics, long cycles, and reliable safety. As of now, the research for electrochemical proton energy storage entails more holistic considerations. In this review, we provide a timely and comprehensive review of recent advances in electrochemical proton storage. First, we discuss the main explored proton storage electrode materials, including carbon materials, metal oxides, Prussian blue, COFs, and MXenes, from the aspects of structure, preparation strategy, and proton storage mechanism. Furthermore, we systematically focus on their multifunctional applications of proton supercapacitors including flexible and wearable electronics, anti-freezing energy storage system, etc. Finally, the challenges and prospects of flexible proton supercapacitors are outlined. We believe that this review will greatly improve the knowledge of proton energy storage and facilitate the development of advanced electrochemical energy systems.