Trinaphthylenehexone: Toward High‐Energy and High‐Stability Small‐Molecule Quinone Cathode Materials

Abstract Sustainable and structurally designable organic cathode materials hold immense promise for rechargeable lithium batteries, yet the dissolution issue poses a significant challenge to their cycling stability. For small‐molecule organic cathode materials (SMOCMs), extending the π‐conjugated system is an effective method to mitigate dissolution, however, remains a huge challenge if requiring high energy density and affordable synthesis concurrently. Herein, a novel quinone‐based SMOCM is successfully synthesized though a straightforward dehydrocyclization reaction of 1,4‐naphthoquinone (NQ), namely 5,6,11,12,17,18‐trinaphthylenehexone (TNHO). It boasts a high theoretical capacity of 343 mAh g −1 (based on a six‐electron reaction), which can be nearly completely utilized with two distinct discharge voltage plateaus at 2.55 and 2.10 V. The extensive π‐conjugated system grants TNHO an exceptional insolubility in the electrolyte. Within an optimized voltage window of 0.8–3.8 V, TNHO achieves a superior capacity retention of 76% after a cycling of 800 cycles at 100 mAh g −1 , spanning a duration of half a year. In addition to the excellent electrochemical performance, an in‐depth investigation has also been conducted into the causal chains linking the voltage window, dissolution–redeposition behavior, electrode structure evolution, and cycling stability. The insights obtained are crucial for directing the ongoing advancement of SMOCMs.