Fully Conjugated Anthraquinone‐Quinoxaline Derivative Cathode Enabling a Superior Zn‐Ion Storage at Extremely Low Temperature −50 °C.

Small molecule organic materials have been considered promising candidates as cathodes in aqueous zinc‐ion batteries (AZIBs) because of their low cost, environmental friendliness, and sustainable production. However, the rapid capacity fading and sluggish kinetics restrict their practical applications, especially under extremely low temperatures (−50 °C). Here, by the condensation of hexaketocyclohexane octahydrate (HKCO) and 1, 2‐diaminoanthraquinone (DQ), a fully conjugated organic molecule, anthraquinone‐quinoxaline derivative (HATAN) is prepared. With the fully conjugated structure, HATAN possesses enhanced π‐electron delocalization and strong intermolecular interaction, which ensure superior electronic conductivity and physicochemical/electrochemical stability. Additionally, the introduction of multiple redox‐active sites (C═O and C═N) can increase the theoretical capacity of HATAN. Consequently, the HATAN cathode for AZIBs exhibits remarkable capacity, long lifespan, and high‐rate capability. Even at −50  C, an exceptional capacity of 75.4 mAh g−1 and 98% capacity retention over 1500 cycles can be preserved. This study presents valuable insights into the structure design of small molecule organic cathodes for advanced AZIBs which can efficiently operate at −50 °C. [ABSTRACT FROM AUTHOR]