60,000 charge–discharge cycles. A charging time of around three minutes. And the key material is a polymer made from cyclodextrin
Researchers at Flinders University in Australia have developed a new aqueous zinc–iodine battery in which cyclodextrin plays a surprisingly sophisticated role: it acts as a molecular cage that helps keep iodine-based species dissolved. The results, published in Angewandte Chemie International Edition in August 2026, point to a potentially attractive new approach to large-scale energy storage.
Why do we need improved battery?
Lithium-ion batteries have become the dominant technology for everything from smartphones to electric cars and grid storage. But for stationary, large-scale energy storage, other properties become increasingly important: cost, safety, resource availability and lifetime.
This is where aqueous zinc batteries are interesting.
Instead of an organic electrolyte, the battery developed by the Flinders team uses a water-based electrolyte. Zinc is used as the metal electrode, while iodine is involved in the positive electrode reaction. Water-based batteries have an obvious advantage: they avoid many of the flammability concerns associated with conventional lithium-ion batteries.
But zinc–iodine batteries have a problem of their own.
The iodine wants to escape
During charging and discharging, iodine can form several iodine-containing species, including polyiodides. Some of these species can migrate through the battery from one electrode to the other. This phenomenon is often called the polyiodide shuttle effect.
The cavities of the cyclodextrin units can interact with polyhalide species and help confine them within the cathode while still allowing the electrochemical reactions to proceed.
This is a particularly elegant example of how a principle familiar from supramolecular chemistry can be transferred into an entirely different technological field.
The same host–guest chemistry that can be used to encapsulate a drug molecule can, in this case, help control the movement of electrochemically active iodine species.
60,000 cycles is the headline number
The researchers report that their poly(β-cyclodextrin)-based zinc–iodine batteries can operate for more than 60,000 cycles.
Under one of the reported conditions, the battery could be charged in approximately three minutes and still operate beyond 60,000 cycles, with a capacity of around 150 mAh/g. In another operating mode, the system retained high stability while using a four-electron iodine storage mechanism. For perspective, 60,000 cycles is an enormous number. If a battery were cycled once every day, 60,000 cycles would correspond to more than 160 years of daily cycling.
Of course, this does not mean that a commercial battery built tomorrow would last 160 years. Laboratory cycle-life measurements are performed under controlled conditions, and the lifetime of a complete battery system depends on many other components and operating conditions.
Nevertheless, the number demonstrates something important: the chemistry can remain remarkably stable over an exceptionally large number of charge–discharge cycles.
How much energy can it store?
The reported system operates at around 1.3–1.4 V in the two-electron storage regime. The researchers report capacities around 205 mAh/g, while the extended four-electron chemistry can reach approximately 365 mAh/g under suitable conditions.
These numbers need to be interpreted carefully.
This is not a drop-in replacement for the lithium-ion battery in a smartphone or electric car. The voltage of aqueous zinc–iodine chemistry is substantially lower than that of a typical lithium-ion cell. Consequently, the technology is much more interesting for applications where safety, cost, rapid cycling and extremely long lifetime matter more than maximum energy density.
Think of stationary storage rather than electric cars.
A solar farm, for example, does not need its battery to be as light as possible. It needs the battery to absorb and release energy reliably, thousands upon thousands of times.
Is this the next lithium-ion battery?
Probably not — at least not yet.
The researchers themselves are positioning the technology primarily toward large-scale energy storage, and they are now working toward establishing a prototyping platform with industry.
There are still many questions before laboratory performance can become a commercial battery: scaling the electrodes, engineering complete cells, long-term operation under realistic conditions, energy density at the full-device level, manufacturing costs, electrolyte management and the behaviour of the zinc electrode over very long periods.
How was the cyclodextrin polymer synthesized?
The polymerization reaction was demonstrated in the supplementary material document of the journal paper [1]. Beta-CD was dissolved in N,N-dimethylacetamide (DMAc). Subsequently, 1,6-hexamethylene diisocyanate (HDI) was dissolved in DMAc and added dropwise to the reaction mixture. The molar ratio of CD to HDI was varied from 1:1 to 1:3 to regulate the degree of cross-linking.
The mixture was stirred and heated at 70 °C for 24 h under an argon atmosphere. It was observed that gelation occurred only when the CD/HDI molar ratio reached 1:3, indicating the formation of a sufficiently cross-linked polymer network. At lower linker contents (CD/HDI < 1:3), no stable gel was formed, suggesting insufficient cross-linking density.
After the reaction was complete, the mixture was cooled to room temperature. When the molar ratio of CD/HDI was 1:3, a substantial amount of gel-like solid formed. The excess solvent was removed, and the resulting polymer was thoroughly washed with cold methanol to remove residual solvent and unreacted species. The solid product was then collected by filtration.
The crude polymer was further purified by Soxhlet extraction with refluxing methanol to eliminate unreacted monomers and low-molecular-weight oligomers. Subsequently, the purified polymer was repeatedly washed with water and dried thoroughly.
[1] Jiang, S., Pei, Z., Shi, Y., Zhang, K., Chalker, J. M., Fraser-Miller, S. J., Coote, M. L., & Jia, Z. (2026). Caging polyhalide anions in polycyclodextrin for long-lasting aqueous zinc-iodine batteries. Angewandte Chemie International Edition, e6010682. https://doi.org/10.1002/anie.6010682