From P‐Type to Bipolar: A Quinone‐Core Engineering Strategy in D‐A‐D Organic Cathodes for Ultra‐Stable and High‐Energy Organic Lithium‐Ion Batteries

Abstract

ABSTRACT In this study, we present a rational donor‐acceptor‐donor (D‐A‐D) molecular design strategy to develop high‐performance organic cathodes by enhancing the intramolecular charge transfer (ICT) effect. We designed and synthesized two organic molecules: 2,6‐bis(10H‐phenothiazin‐10‐yl)benzo[1,2‐d:4,5‐d’]diimidazole‐4,8‐dione (PTZBQ), featuring a strong quinone‐type acceptor core, and the control compound 2,6‐bis(10H‐phenothiazin‐10‐yl)benzo[1,2‐d:4,5‐d’]diimidazole (PTZTAB), without a quinone core. The strong push‐pull electronic structure of PTZBQ not only results in a significantly narrowed bandgap and improved electrode kinetics, but also allows the quinone core to contribute extra n‐type capacity, thereby remarkably boosting the electrode's specific capacity and reaction dynamics. Moreover, the extended π‐conjugation and D‐A‐D configuration‐induced polarity endow both small molecules with exceptional electrolyte dissolution resistance. Consequently, PTZBQ exhibits bipolar redox activity, delivering a high discharge potential of 3.05 V, a high specific capacity of 163.3 mAh g −1  at 0.1 A g −1 , an excellent rate capability (77.6% retention at 5 A g −1 ), and exceptional long‐term cycling stability with 89.4% retention after 5000 cycles at 1 A g −1 . DFT calculations and ex situ spectroscopy confirm that the unique D‐A‐D architecture possesses spatially separated n‐type and p‐type redox centers, facilitating the redox process. Our findings highlight that quinone‐core engineering enhances intramolecular charge transfer and represents a powerful approach for developing high‐performance cathode materials.