Worldwide Universities Network researchers used cheap and abundant starting materials to synthesize a low-molecular-weight organic electrode material and achieved a significant performance increase with different battery chemistries. The new cathode material had unparalleled cycling stability, ultra-high capacity and rate capability in aqueous zinc-ion batteries.
Researchers at the Worldwide Universities Network have started a research project to develop conductive electrode materials with very low levels of toxic metals. They have synthesized polymeric porous materials based on abundant and environmentally friendly components as battery electrodes. They have also designed ion-conducting functional materials as solid-state electrolytes to improve electrochemical performance.
Their key result was the development of a low molecular weight organic electrode material, hexazathiantranylene (HATA) embedded quinone (HATAQ). By introducing conjugated quinone moieties into an electron-deficient hexazatriphenylene derivative core, HATAQ with a very long π-conjugation showed the potential to produce a very high capacity for metal ion storage.
“Organic electrode materials have many advantages, such as low cost and environmental friendliness,” said Professor Watchareeya Kaveevivitchai of National Cheng Kung University (NCKU) in Taiwan. “They also contain a large number of redox-active sites capable of undergoing a multi-electron transfer process at the redox potential, which when properly fine-tuned can lead to high energy density.”
Inspired by HATAQ’s excellent electrochemical performance in lithium-ion batteries, researchers have explored the compound as a cathode in other rechargeable battery systems known to be safer and less expensive, such as sodium, zinc, and other multivalent systems.
Especially in rechargeable aqueous zinc-ion batteries with 1 M ZnSO4 solution as electrolyte, a large number of redox active sites and extended conjugation enabled HATAQ’s extremely high capacity of 492 mAh g−1 50 mA g−1 and excellent speed up to 20 A g−1 199 mAh g−1 reversible capacity corresponding to 99% retention after 1,000 cycles.
The researchers say that HATAQ’s performance is one of the best ever reported for an aqueous zinc-ion battery. They discussed their findings”Proton-Driven Biomimetic Stabilization of Small-Molecular Organic Cathode in Aqueous Zinc-Ion Batteries“, which was published recently Journal of Materials Chemistry A.