A High-Potential Bipolar Phenothiazine Derivative Cathode for Aqueous Zinc Batteries

Graphical A novel molecule (PTDM) containing n-type and p-type redox sites was prepared. By exploiting the synergistic advantages of two-type redox sites of PTDM, the aqueous PTDM//Zn cell delivers a high average voltage of ~1.13 V, a decent specific capacity of 118.3 mAh g −1 at 0.1 A g −1 and moderate capacity retention of 65.6 % over 6400 cycles at 1 A g −1 . Aqueous zinc ion batteries (AZIBs) are gaining popularity as advanced energy storage devices that are economical, safe, and use resource-abundant storage options. In this study, we have synthesized a bipolar phenothiazine organic scaffold known as 3,7-bis(melaminyl)phenothiazin-5-ium iodide (PTDM), which is obtained by undergoing nucleophilic substitution through phenothiazinium tetraiodide hydrate (PTD) and melamine. Electrochemical results indicate that PTDM can act as a high-potential cathode material for rechargeable AZIBs. In detail, the aqueous PTDM//Zn full cell exhibits a high average voltage of approximate 1.13 V, along with a specific capacity of 118.3 mAh g −1 at 0.1 A g −1 . Furthermore, this demonstrated cell displays moderate long-term cycling stability over 6400 cycles, which is encouraging and suggests potential for developing advanced organic electrode materials for rechargeable AZIBs.