Adelaide, Australia – Researchers at the University of Adelaide have announced a significant advancement in zinc-iodine battery technology, demonstrating performance capabilities that could double the energy density of current lithium-ion models. This breakthrough, detailed in the journal Joule, introduces a novel dry processing technique for iodine cathodes, marking a pivotal step towards safer, more cost-effective, and environmentally sustainable large-scale energy storage solutions.

The core of the innovation lies in the dry processing of iodine cathodes, a departure from traditional wet mixing methods. Professor Shizhang Qiao, Chair of Nanotechnology and Director of the University’s Materials Engineering Center, explained that this dry technique prevents iodine loss, thereby improving overall battery performance and enabling higher active material packing for increased capacity. Traditional wet mixing, conversely, has been shown to diminish energy density, cycle life, and general performance in zinc-iodine systems.

Further enhancing the battery’s stability and capacity, the research team incorporated a flexible protective film applied to the zinc during charging. This film effectively mitigates the risk of short circuits caused by uneven zinc deposition, a common challenge in zinc-based battery systems. The application of this coating creates a more stable electrode surface, directly contributing to the battery’s improved capacity and longevity.

Aqueous zinc-iodine batteries have emerged as a promising candidate for grid-scale energy storage due to their intrinsic safety, low cost, and environmental compatibility. Compared to lithium-ion batteries, which currently dominate the grid storage market, zinc-based systems offer distinct advantages in resource availability and thermal stability. Historically, the primary impediment to their widespread adoption has been their comparatively poor performance, largely attributed to limitations in electrode preparation. This new dry processing method directly addresses that hurdle, potentially unlocking the next generation of high-performance, large-scale energy storage.

As global energy grids increasingly integrate intermittent renewable sources like solar and wind, robust and affordable energy storage becomes paramount for maintaining grid stability and ensuring reliable power supply. Professor Qiao highlighted the scalability of the new technique, stating, “Production of the electrodes could be scaled up by using reel-to-reel manufacturing. By optimizing lighter current collectors and reducing excess electrolytes, the overall system energy density could be doubled from around 45 watt-hours per kilogram (Wh kg−1) to around 90 Wh kg−1.” This potential for increased energy density, coupled with the inherent safety and lower cost of zinc-iodine chemistry, positions the technology to significantly streamline the energy transition and potentially lead to reduced energy costs for consumers. The research team also plans to explore the performance of other halogen chemistries, such as bromine systems, using the same dry-process approach, signaling further advancements in this promising field.