Zinc-iodine battery reaches 60,000 cycles in lab

Flinders University’s battery can be charged and discharged for more than 60,000 cycles. The aqueous zinc-iodine battery can be fully charged in three minutes while delivering 150 mAh/g, according to the team’s study published in Angewandte Chemie International Edition.

The chemistry addresses a specific weakness in zinc-iodine batteries. Polyiodine species can move through the separator between the battery’s electrodes, a leakage known as the shuttle effect. Over time, that movement degrades performance. The Flinders team used a cyclodextrin-based polymer as a microscopic host: its hydrophilic exterior and hydrophobic interior cavity trap and release polyhalides, including polyiodine species, rather than letting them shuttle freely.

The polymer is derived from inexpensive, biodegradable oligosaccharides produced from starch. The battery operates at 1.3 to 1.4 volts. When configured for a higher capacity of 200 mAh/g, it runs for 8,000 cycles with a seven-minute full charge; at 150 mAh/g, the reported lifetime exceeds 60,000 cycles.

And so what, concretely? For large-scale energy storage, a water-based zinc-iodine battery could offer a route built around zinc rather than lithium. Australia holds 20%–28% of the world’s known zinc reserves and resources, while the country produces about 3,300 metric tons of lithium-ion battery waste a year, a figure expected to rise to more than 136,000 metric tons by 2036. The numbers point to a potential local supply and recycling advantage, though they do not yet establish a commercial product.

That gap is still visible. Zhongfan Jia, an associate professor of chemistry at Flinders University, says the group is working with industry to establish a prototyping platform. For now, the cycle life and charging figures come from the research team’s battery study; the next step is to see whether the polymer cage and its performance hold up in a larger prototype and in operating conditions beyond the laboratory.