Scientists in Australia have developed a rechargeable zinc-iodine battery that can survive more than 60,000 charging cycles, potentially offering a safer and more sustainable option for storing renewable energy.
The battery was developed by researchers at Flinders University and is designed for large-scale energy storage rather than devices such as phones and laptops.
The team says the technology could eventually help store electricity generated by solar and wind farms, where long battery life and low cost are especially important.
Most rechargeable batteries today rely on lithium.
But growing demand from electric vehicles, electronics and energy storage systems is putting pressure on lithium supplies and creating concerns about cost, safety and recycling.
Zinc-iodine batteries offer a possible alternative. They use a water-based system, making them potentially safer than conventional lithium-ion batteries, which contain flammable organic materials.
However, zinc-iodine batteries have faced an important technical problem. During charging and discharging, iodine can form substances called polyiodides. These can move through the battery’s separator, causing energy loss and gradually reducing battery performance.
The Flinders team tackled this problem with an unusual material made from cyclodextrins, which are ring-shaped sugar molecules produced from starch. Cyclodextrins are already widely used in foods, medicines and cosmetics.
Their structure makes them particularly useful for batteries. Each molecule has a cavity that can capture certain substances. The researchers created a low-cost material using cyclodextrins that acts somewhat like a microscopic cage, trapping troublesome iodine compounds while still allowing the battery’s chemical reactions to take place.
The results were impressive. In one test, the battery maintained a capacity of about 200 milliampere-hours per gram for more than 8,000 cycles and could be fully charged in seven minutes. Under another testing condition, it delivered about 150 milliampere-hours per gram for more than 60,000 cycles, with charging taking only three minutes.
Associate Professor Zhongfan Jia said the approach could help make zinc-iodine batteries both sustainable and extremely long-lasting. His team is now working with industry to establish a platform for developing battery prototypes.
The technology could be particularly attractive for Australia. The country has some of the world’s largest known zinc resources and is already a major zinc producer and exporter.
At the same time, Australia’s lithium-ion battery waste is expected to increase dramatically in coming years, from about 3,300 metric tons annually to more than 136,000 metric tons by 2036.
The researchers believe locally available zinc, combined with inexpensive materials derived from starch, could eventually provide Australia with another way to build safer and more sustainable energy-storage systems.
