Researchers at the University of Adelaide have developed a new dry process for electrode manufacturing offering more than twice the performance of conventional alternatives.
Zinc-iodine batteries have been one of the options posed as a sustainable and affordable alternative to lithium-ion batteries. However, the performance of the aqueous zinc–iodine battery chemistry has so far been considerably lower than for the Li-ion batteries.
The research team, led by professor Shizhang Qiao, Chair of Nanotechnology, and Director, Centre for Materials in Energy and Catalysis, at the School of Chemical Engineering, discovered a new dry electrode technique for zinc–iodine batteries that avoids traditional wet mixing of iodine.
“We mixed active materials as dry powders and rolled them into thick, self-supporting electrodes. Then we added a small amount of 1,3,5-trioxane to the electrolyte, which turns into a flexible protective film on the zinc surface during charging.”
This film keeps zinc from forming sharp dendrites – needle-like structures that can form on the surface of the zinc anode during charging and discharging – that can short the battery. The same problem occurs in lithium-ion batteries, meaning faster degradation of the electrodes.
“The new technique for electrode preparation resulted in record-high loading of 100 mg of active material per cm2,” said Han Wu, Research Associate at the University of Adelaide.
“After charging the pouch cells we made that use the new electrodes, they retained 88.6 per cent of their capacity after 750 cycles and coin cells kept nearly 99.8 per cent capacity after 500 cycles. We directly observed how the protective film forms on the zinc by using synchrotron infrared measurements.”
Professor Qiao said that the new technology will benefit energy storage providers – especially for renewable integration and grid balancing.
The team published their results in the journal Joule:
Image: Zinc-iodine battery. Credit: University of Adelaide.
