Recent Progress of the Cathode Material Design for Aqueous Zn-Organic Batteries

Aqueous zinc-ion batteries (ZIBs) have emerged as the most promising candidate for large-scale energy storage due to their inherent safety, environmental friendliness, and cost-effectiveness. Simultaneously, the utilization of organic electrode materials with renewable resources, environmental compatibility, and diverse structures has sparked a surge in research and development of aqueous Zn-organic batteries (ZOBs). A comprehensive review is warranted to systematically present recent advancements in design principles, synthesis techniques, energy storage mechanisms, and zinc-ion storage performance of organic cathodes. In this review article, we comprehensively summarize the energy storage mechanisms employed by aqueous ZOBs. Subsequently, we categorize organic cathode materials into small-molecule compounds and high-molecular polymers respectively. Novel polymer materials such as conjugated polymers (CPs), conjugated microporous polymers (CMPs), and covalent organic frameworks (COFs) are highlighted with an overview of molecular design strategies and structural optimization based on organic cathode materials aimed at enhancing the performance of aqueous ZOBs. Finally, we discuss the challenges faced by aqueous ZOBs along with future prospects to offer insights into their practical applications. Organic compounds with the advantages of renewable resources, environmental friendliness, and diverse structures have attracted tremendous interests on aqueous energy storage field. This review focuses on the energy storage mechanism of the aqueous Zn-organic battery and the recent advances of various organic cathodes including small-molecule compounds and polymers. Especially novel organic polymer materials, including conjugated polymers (CPs), conjugated microporous polymers (CMPs), and covalent organic frameworks (COFs) are reviewed in detail. In addition, we also discuss the remaining challenges and future development of the organic cathode in aqueous ZOBs.image