Zinc-air batteries with non-alkaline, aqueous electrolytes


From pv magazine Germany

Scientists around the world are looking for post-lithium storage technologies and an interesting option is represented by zinc-air batteries. These storage systems, however, still struggle with a high level of chemical instability, which ultimately leads to electrochemically-irreversible damage.

A group of researchers led by Wei Sun from the MEET Battery Research Center at the Westphalian Wilhelms University in Münster, wants to overcome the technical weaknesses of conventional zinc-air batteries by using innovative battery chemistry based on non-alkaline, aqueous electrolytes.

The results of their research, in which the Fudan University in Shanghai, the University of Science and Technology in Wuhan, the University of Maryland and the U.S. Army Research Laboratory were also involved, have been published in the journal Science. “Our innovative, non-alkaline electrolyte brings a previously unknown reversible zinc peroxide (ZnO2)/O2 chemistry to the zinc-air battery,” explained Sun.

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Conventional electrolytes used thus far were strongly alkaline. The new battery chemistry is based on the salt of zinc trifluoromethanesulfonate, which is claimed to have several advantages, Sun said, noting that the zinc anode is used more efficiently thanks to its higher chemical stability and electrochemical reversibility.

The zinc-air batteries developed with this chemistry could be operated stably for 320 cycles and 1,600 hours. The influence of the ZnO2/O2 battery chemistry and the role of the hydrophobic trifluoromethanesulfonate anion were systematically investigated with the help of electrochemical and analytical techniques and with simulations formulated at multiple scales.

The scientists ascertained that the batteries have a higher energy density and that these devices can potentially compete with currently dominant lithium-ion storage systems. “However, this technology needs further, intensive research and optimization before it can be used in practice,” said Sun.

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