Researchers Develop Safer Water-Based Battery Chemistry

A research team led by University College London has developed a new chemical approach to improve the performance of aqueous, or water-based, batteries. This advancement offers a potential path toward safer and more sustainable energy storage compared to traditional lithium-ion technology. The findings were recently published in the journal Nature. Aqueous batteries are generally considered safer because they do not carry the same fire risks associated with the flammable electrolytes found in standard lithium-ion cells. However, these water-based systems have historically struggled with lower energy density, which has limited their practical use in large-scale applications. The researchers addressed this limitation by focusing on iodine, a primary material used for energy storage within the battery. By enabling iodine to transfer four electrons instead of the usual two during charging and discharging, the team effectively increased the amount of energy the battery can store. A significant challenge in this process is that hypervalent iodine cations are highly reactive when placed in water. Previous attempts to stabilize these reactions required the use of highly concentrated, corrosive, and expensive halogen-containing electrolytes. The team at University College London designed an entirely new electrolyte chemistry that avoids these harsh materials. They achieved this by engineering the local molecular environment around the iodine. Some molecules were designed to block water from reaching the iodine, while others bind to its reactive forms to prevent unwanted chemical reactions. The researchers tested the durability of their design using zinc-iodine batteries. They found that the cells retained nearly all of their storage capacity even after undergoing thousands of charge-discharge cycles. The new design proved reliable across different configurations, including pouch cells used in mobile devices and smaller coin cells. The team noted that this approach could also be adapted for use in aluminium-iodine batteries. This flexibility suggests the technology may be applicable to a wide range of future energy-storage systems. As the global transition to renewable energy continues, the need for large-scale battery farms to store excess power remains a priority. This development provides a promising step toward more stable and environmentally friendly alternatives for grid-scale energy storage.