Trinaphthylene–Hexaone: A Cathode for Zn‐Ion Battery and Potential Anode for Li‐Ion Battery Applications

Organic metal-ion batteries provide cost-effective, eco-friendly, and safer alternative for large-scale energy storage over conventional technologies. Among these systems, aqueous zinc-ion batteries (AZIBs) are particularly promising for safe and sustainable applications, motivating the development of new organic electrodes. However, designing new organic cathodes remains challenging, as they frequently suffer from structural degradation, sluggish reaction kinetics, and limited cycling stability, which contribute to gradual capacity fading. Herein, trinaphtylene-5,6,11,12,17,18-hexaone (TNH) is explored as novel organic cathode for AZIBs and anode for lithium-ion batteries (LIBs), showing excellent cycling stability (1920 cycles), rate capability (60 mAh g^-1 at 5 A g^-1), and long cycle life in AZIBs due to extended π-conjugation, electrolyte insolubility, and multiple redox sites. Several ex-situ characterizations were employed to verify the role of ─C═O group as redox-active center responsible for Zn²⁺ storage. The Li//TNH cell showed high initial capacity of 1120 mAh g^-1 and stable cycling at ∼510 mAh g^-1 over 100 cycles, highlighting its potential for future LIBs and Li-based supercapacitors. The enhanced capacity of Li//TNH cell, surpassing theoretical 343 mAh g^-1 from carbonyl redox activity, is due to capacitance from electron ring current polarization by Li⁺ ions. This showcases the promise of novel organic materials for future energy storage.