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Australian researchers have developed a new class of solid electrolytes for rechargeable aqueous zinc-iodine batteries, extending their useful life and increasing their efficiency. Symmetrical cells using this electrolyte have demonstrated excellent cycling performance, maintaining stability for approximately 5,000 hours at room temperature, while fully solid ZnI2 batteries have more than 7,000 cycles with a capacity retention greater than 72.2 %.
Rechargeable zinc-iodine (ZnI2) batteries have received much attention due to their inherent advantages, such as natural abundance, low cost, safety, and high theoretical capacity. However, its limited life cycle remains a major challenge for practical applications.
Specifically, the thermodynamic instability of the zinc electrode in an aqueous electrolyte always causes the release of hydrogen, which causes the cell to swell and eventually fail. Additionally, ZnI2 batteries are also prone to dendrite growth, which can damage the separator and lead to battery failure.
Now, researchers at the University of Queensland, Australia, have developed a new class of fluorinated block copolymers as solid electrolytes for all-solid-state ZnI2 batteries with longer lifetimes.
Their results demonstrate the formation of a solid electrolyte interphase (SEI) layer on zinc, which promotes horizontal zinc growth, mitigates dendrite penetration, and improves battery cycle life.
Symmetrical cells using this electrolyte demonstrate excellent cycle performance, maintaining stability for approximately 5,000 hours at room temperature, while solid-state ZnI2 batteries exhibit more than 7,000 cycles with a capacity retention greater than 72.2%. .
The full ZnI2 battery has a Coulombic efficiency of almost 100% for more than 7,000 cycles (more than 10,000 hours).
Furthermore, the electrolyte has excellent performance, with a reversible capacity of 79.8 mAh g-1 even at ultra-high current densities of 20 ºC. |
