Organic compounds have recently been demonstrated to be alternative cathodes to inorganic ones for aqueous zinc-ion batteries (ZIBs), while the limited electrochemical performance greatly restricts their applications, which is partly attributable to their small π-conjugated systems. Here, to extend the π-conjugated system, diquinoxalino[2,3-a:2′,3′-c]phenazine (DQP) was designed and prepared, intriguingly exhibiting an ultrahigh capacity of 413 mA h g^–1 at 50 mA g^–1 for ZIBs. In addition, the combination of detailed density functional theory calculations and ex situ characterization techniques, such as IR and X-ray photoelectron spectroscopy spectra, clearly reveals the electrochemically active C═N bonds transformation in charging and discharging circulation. Moreover, the results also demonstrate that the extended π-conjugated system with active C═N bonds is associated with enhanced electrochemical stability, conductivity, and reversible capacity. Besides, owing to its excellent insolubility in water, DQP also delivers high capacity retention of 86% after 1000 cycles at 5 A g^–1. Thus, this work provides a reasonable strategy for organic cathodes applied in aqueous ZIBs.

中文翻译：

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具有活性C═N键的有机阴极扩展π共轭体系，用于驱动水性锌离子电池

最近，有机化合物已被证明是水性锌离子电池（ZIBs）的无机阴极的替代阴极，而有限的电化学性能极大地限制了它们的应用，这部分归因于它们小的π共轭体系。在这里，为了扩展π共轭体系，设计并制备了二喹喔啉[2,3- a：2'，3'- c ]吩嗪（DQP），在50 mA g时表现出413 mA hg ^–1的超高容量^–1ZIB。此外，将详细的密度泛函理论计算与非原位表征技术（例如IR和X射线光电子能谱）相结合，清楚地揭示了充放电循环中电化学活性C═N键的转变。此外，结果还表明，具有活性C═N键的扩展π共轭体系与增强的电化学稳定性，电导率和可逆容量有关。此外，由于其在水中的出色不溶性，DQP在5 A g ^–1的1000次循环后还具有86％的高容量保持率。因此，这项工作为在水性ZIBs中应用有机阴极提供了合理的策略。