High-Performance Polydiacetylene Organic Cathode for Zinc-Ion Batteries

Abstract

Organic cathodes are considered promising alternatives to metal-based electrodes in energy storage devices because of their versatile structural and electrochemical properties and benign environmental impact. Most organic cathodes in zinc ion batteries (ZIBs), however, exhibit small potential windows (<1.0 V vs. Zn²⁺/Zn), display poor cycling performance, as well as insufficient chemical stability, limiting their practical applicability. Here, we present a high-performance organic cathode, utilizing, for the first time, polydiacetylene (PDA) -a conjugated polymer exhibiting unique structural and electronic properties. Specifically, a ZIB comprising anthraquinone-functionalized polydiacetylene cathode doped with polyaniline (PANI) and Zn(ClO₄)₂/acetonitrile as electrolyte featured exceptionally high specific capacity (330 mAh g -1 at 0.1 A g -1 ) and energy density (277 Wh kg -1 at 0.1 A g -1 ), excellent rate capability, and long-term cycling stability. Structure/function analyses indicate that the superior electrochemical properties of the polydiacetylene-based cathode are ascribed to efficient diffusion and Zn 2+ coordination with the redox-active quinone units of anthraquinone and benzenoid/quinoid residues of PANI. The polydiacetylene-based cathode, fabricated from inexpensive and readily synthesized building blocks, is environmentally friendly and resilient, and may be successfully utilized in commercially viable organic ZIBs.