Claire Watson reports via ScienceAlert: By replacing harmful chemical electrolytes used in commercially available batteries with water, scientists have developed a recyclable 'water battery', with new technology potentially offering a safer and more environmentally friendly alternative. Solved an important problem. “Water batteries” are officially known as water-based metal ion batteries. These devices use metals such as magnesium and zinc, which are cheaper to assemble and less toxic than materials currently used in other types of batteries.
Batteries store energy by creating a flow of electrons that move from the positive end (cathode) to the negative end (anode) of the battery. Energy is consumed when electrons flow in the opposite direction. The liquid in the battery is there to shuttle electrons back and forth between the two ends. In water batteries, the electrolyte is water with some salts added, rather than something like sulfuric acid or lithium salts. Importantly, the team behind this latest advancement has devised a way to prevent these water batteries from shorting out. This happens when small, pointy metal growths called dendrites form on the metal anode inside the battery and break through the battery compartment. […]
To combat this, the researchers coated the batteries' zinc anodes with bismuth metal, which oxidizes and forms rust. This forms a protective layer that prevents dendrite formation. This feature also helped extend the lifespan of the prototype water battery, which researchers showed in experiments that it retained more than 85 percent of its capacity after 500 cycles. The team has previously developed water-based prototypes for coin-sized batteries used in watches, as well as cylindrical batteries similar to AA and AAA batteries, according to Lois Krumerovs of the Guardian. . The research team is working to improve the energy density of water batteries, making them comparable to compact lithium-ion batteries housed in pocket-sized devices. Magnesium is their preferred material, being lighter than zinc and having a higher potential energy density. [I]If magnesium-ion batteries are commercialized, the technology could replace bulky lead-acid batteries within a few years. The study was published in the journal Advanced Materials.
