Evaluation of the Interphase-Related Cycling Stability of Thin-Film Amino- and Hydroxy-Substituted Anthraquinone Electrodes for Sodium-Ion Batteries

This study investigates sustainable approaches to designing organic cathode materials for sodium-ion batteries, aiming to replace traditional metal-based electrodes. Organic materials present a promising alternative due to their lower environmental impact, supply chain stability, and tunable electrochemical properties. In this work, the electrochemical performance of 12 commercially available amino- and hydroxy-substituted anthraquinone derivatives, including several naturally occurring compounds, was systematically evaluated in sodium-ion battery systems. By focusing on readily available commercial materials, this study identified the most stable and effective candidates for organic cathodes in sodium-ion batteries. Notably, the majority of these derivatives have never been tested in galvanostatic cycling in either lithium or other post-lithium battery systems. Through systematic testing, challenges such as high solubility and limited redox reactivity were addressed, demonstrating how careful material selection can yield high-performance, long-cycle-life organic cathodes. The performance of these materials was found to be strongly influenced by their solubility in the electrolyte as well as their structural and electronic properties, including electron-accepting capabilities and sodium coordination behavior. Among the studied materials, 1,8-dihydroxy-anthraquinone and 1,8-diamino-anthraquinone demonstrate superior cycle stability, maintaining 72% and 73% capacity retention, respectively, over 100 charge-discharge cycles, followed by 1,5-diamino-anthraquinone and 1-hydroxy-anthraquinone with 64% and 66%. These findings not only advance the development of organic cathode materials for sodium-ion batteries but also highlight the potential of sustainable material choices to enable scalable and environmentally friendly energy storage solutions, supporting the transition to a greener energy future.