Molecular Engineering Empowers Phenanthraquinone Organic Cathodes with Exceptional Cycling Stability for Lithium- and Aqueous Zinc-Ion Batteries.

Organic electrode materials have garnered great attention in recent years, owing to their resource sustainability, structural diversity, and superior compatibility with various ionic species. Among them, quinone-based compounds have attracted particular interest. Notably, compared with para-quinone analogs (e.g., anthraquinone), ortho-quinone-based electrode materials (e.g., phenanthraquinone) demonstrate higher redox potential, which contributes to achieving higher energy density in battery applications. However, their practical applications have been limited by severe solubility in electrolytes, resulting in poor cycle performance. To improve it, two novel phenanthraquinone-derived molecules, 1,4-bis(9,10-phenanthraquinonyl)benzene (BPQB) and 1,3,5-tri(9,10-phenanthraquinonyl)benzene (TPQB), are rationally designed, synthesized, and applied as cathode materials for both lithium-ion batteries (LIBs) and aqueous zinc-ion batteries (AZIBs). Comprehensive electrochemical evaluations reveal remarkable cycling stability and rate performance of TPQB. The TPQB cathodes for LIBs achieve a high-capacity retention of 76.8% after 1,000 cycles at 5 C, while exhibiting extraordinary ultra-long cycle life in AZIBs with 93.2% capacity retention over 6,000 cycles at 5 C. Their charge storage mechanisms are elucidated through various characterization methods. The work presents a novel molecular engineering strategy that effectively inhibits the dissolution of phenanthraquinone-derived electrode materials and thus realizes excellent electrochemical performance across diverse battery systems.