Safer lithium-ion battery uses water as electrolytic solution

A prototype lithium-ion battery that uses water as an electrolytic solution Provided by Yokohama National University Researchers working to develop a safer lithium-ion battery free of the risk of catching fire found a solution by replacing a flammable organic solvent with water.

A team from Yokohama National University and Sumitomo Electric Industries Ltd. said the new battery is durable and can be quickly recharged, although it has a slightly lower performance level than conventional products.

Within three years the team hopes to make the battery commercially available.

A safer battery with a long life is expected to be put to practical use, though the voltage is slightly lower, said Naoaki Yabuuchi, a chemistry professor at Yokohama National University.

The development was published online in November in the Proceedings of the National Academy of Sciences of the United States of America, the official journal of the National Academy of Sciences.

Lithium-ion batteries are used in smartphones and electric cars. A flammable organic solvent is used as an electrolytic solution.

To improve safety and to make sure there was no fire risk, the researchers used water as the electrolyte to improve safety and study electrode materials to ensure a sufficient performance level.

They found that using a molybdenum oxide for the negative electrode can achieve performance levels required for practical use. Even after the battery was recharged 2,000 times, its capacity dropped by less than 30 percent.

The prototype battery can only be used in lower voltage conditions when water is broken down when high voltage is applied, in comparison to batteries based on organic solvents.

Its weight energy density is an indicator of battery performance, which is about half the size of a conventional product, which means a larger body size is essential to produce a battery with the same capacity.

The researchers believe that the noncombustible, durable alternative will prove useful in storing electricity generated by solar and wind energy and powering short-distance electric vehicles.