Integrated Aqueous Electrochemical Energy Devices

Integrated aqueous electrochemical energy devices (IAEEDs) are emerging as a transformative paradigm in sustainable energy technology, unifying energy generation, storage, and chemical conversion within a single aqueous platform. Unlike conventional electrochemical systems that operate as isolated units, IAEEDs couple an aqueous power source, such as a Zn-air battery (ZAB) or fuel cell, with an electrolytic conversion cell, enabling cyclic operation without external electricity. This integrated strategy fully exploits the inherent merits of aqueous electrolytes, including high safety, low cost, and fast ionic transport, while simultaneously enabling hydrogen production, biomass upgrading, CO2 reduction, and energy storage in one multifunctional system. Recent advances have highlighted the remarkable versatility and promise of these devices for constructing compact, efficient, and sustainable electrochemical technologies. In this Review, the design principles, reaction-coupling strategies, and representative architectures of aqueous IAEEDs are systematically summarized, with particular emphasis on the mechanistic origins of their synergistic performance. Key challenges, including catalyst compatibility, kinetic mismatch, interfacial regulation, and scalable integration, are also critically discussed. Finally, future directions are outlined to guide the development of more efficient, multifunctional, and modular aqueous electrochemical systems.