Researchers develop safer EV battery cell using water

A group of international researchers have developed a safer lithium-ion battery that uses water as the electrolyte to reduce the risk of catching fire, opening the door to developing high-energy, more durable and safer batteries.

As batteries become increasingly prevalent across all segments of society, and in particular as they drive the decarbonisation of the automotive sector, ensuring improved efficiency and safety is vital.

In an effort to do just that, a team of researchers from Japan and Germany, including researchers from Yokohama National University and Sumitomo Electric Industries, have developed a lithium-ion battery that uses water as an electrolytic solution which they say is far safer than traditional electrolytes.

Demonstrated in the journal Proceedings of the National Academy of Sciences of the United States of America, the official journal of the National Academy of Sciences, the authors expect the battery will open “a way to develop high-energy, durable, and safe batteries on the basis of metastable and nanosized oxides with aqueous electrolyte solutions.”

In addition to increased safety through the replacement of a flammable organic solvent with water, the battery can also be quickly recharged – although it is said to have a slightly lower performance level than conventional lithium-ion batteries.

“We now have a safer battery with a long lifespan that is expected to be put to practical use, although the voltage is slightly lower,” said Naoaki Yabuuchi, a chemistry professor at Yokohama National University, who is part of the team and spoke to The Asahi Shimbun, one of Japan’s largest newspapers.

Specifically, a metastable and nanosize molybdenum oxide with a rock-salt structure is used for the negative electrode, providing impressive performance levels necessary for practical use.

There is also less overall degradation over time, with the researchers finding that even when the battery was recharged 2,000 times, its capacity dropped less than 30%, with final discharge capacity resting at 73%.

Even greater capacity is possible, according to the authors, but the weight energy density of the battery is about half the level of a conventional product, meaning that a larger body size is required to produce a battery with the same capacity.