Wide Voltage Aqueous Asymmetric Supercapacitors: Advances, Strategies, and Challenges

Abstract Asymmetric supercapacitors (ASCs) can substantially broaden their working voltage range, benefiting from the advantages of both cathode and anode while breaking through the energy storage limitations of corresponding symmetric cells. Wide voltage aqueous ASCs hold great promise for future electronic systems that require satisfied energy density, power density, and cycle life, due to the advantages of aqueous electrolyte in terms of low cost, operational safety, facile manufacture, environment‐friendly, and high ionic conductivity. This review will first briefly present an overview of the historical developments, charge storage mechanisms, and matching principles of wide voltage aqueous ASCs. Then, the cathode and anode materials with wide potential windows for building wide voltage aqueous ASCs over the last few decades are summarized. The next section details the optimization methods of aqueous electrolyte related to wide voltage aqueous ASCs. In addition, the basic device configurations of wide voltage aqueous ASCs are classified and discussed. Furthermore, several strategies are proposed for achieving high‐performance wide voltage aqueous ASCs in terms of voltage window, specific capacitance, rate performance, and electrochemical stability. Finally, to motivate further research and development, several key scientific challenges and the perspectives are discussed.