Hydrogen-Bonding Boosted Poly(urea-diaminoanthraquinone)s as Superior Cathode Materials for Lithium-Ion Batteries

Organic electrode materials (OEMs) are highly promising candidates for next-generation green batteries. However, achieving rapid redox kinetics and extending their lifespan remain challenging. Herein, a series of linear redox-active anthraquinone-based polyureas (PUAQs) were synthesized and systematically investigated to discover OEMs and explore viable pathways for optimizing and fine-tuning their electrochemical characteristics. The arrangement of amino groups on anthraquinone units is highly correlated with the electrochemical performance of PUAQs. Theoretical calculations and experimental characterizations reveal that poly(urea-2,6-diaminoanthraquinone) (PUAQ26) forms substantially more intermolecular hydrogen bonds (C═O···H–N) and π–π interactions, along with a more ordered structure, compared to poly(urea-1,5-diaminoanthraquinone) (PUAQ15) and poly(urea-1,4-diaminoanthraquinone) (PUAQ14). These enhanced interactions and ordered structure contribute significantly to the enhanced stability and electrochemical dynamics of PUAQ26. As a cathode material for lithium-ion batteries, PUAQ26 exhibits outstanding electrochemical performance. It delivers a high discharge specific capacity of 190 mA h g–1 at 0.2 A g–1 and exhibits excellent long-cycle stability, retaining 165 mA h g–1 after 2000 cycles at 1.0 A g–1 with a 97% retention rate. This study establishes redox-active polyureas as high-performance OEMs, highlighting the pivotal roles of building units topology and intermolecular hydrogen bonding in their performance, thus opening avenues in high-performance OEMs development.