Carbonyl-rich organic cathodes for advanced aqueous batteries: progress and perspectives

Aqueous batteries have garnered significant attention as compelling contenders for large-scale energy storage owing to their inherent safety, cost-effectiveness, and environmental sustainability. Significant endeavors have been dedicated to develop redox-active organic cathode materials, which is considered a crucial factor driving the development of aqueous batteries. Among various cathodes, carbonyl-rich organic compounds demonstrate exceptional potential in view of their strong electroactivity, ion-coupling sensitivity and structural versatility. This mini-review aims to provide a comprehensive understanding on the recent advancements in advanced carbonyl-rich organic materials for aqueous batteries. Firstly, we systematically categorize carbonyl-rich organic materials based on their molecular architecture: small molecules, polymers, and covalent organic frameworks, while elaborating their molecular design strategies and fundamental structure-performance relationships. Subsequently, we thoroughly explore their electrochemical applications in various aqueous batteries, including both metal-ion (e.g., Zn²⁺, Al³⁺, Ca²⁺, Mg²⁺) and non-metallic ion (e.g., H⁺, NH₄⁺) batteries. Furthermore, we conduct a systematic comparison of key performance metrics (capacity, voltage, rate capability, and cycling stability) for these carbonyl-rich organic cathodes in different aqueous batteries. Finally, critical challenges and future perspectives are summarized to fully unlock the potential of carbonyl-rich organic cathodes in next-generation high-performance aqueous batteries.