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University to team up with Japan firms to develop high-capacity, rechargeable battery

Metal deposition is seen formed on the negative electrode made of an unprocessed zinc plate in an experimental zinc-nickel battery after the cell was repeatedly charged and discharged. (Photo courtesy of Doshisha University professor Masatsugu Morimitsu)

OSAKA -- A university in western Japan is set to join hands with some 20 companies to develop a large-capacity, low-cost rechargeable battery, using zinc and nickel as its electrodes.

Kyoto-based Doshisha University and the businesses will set up a consortium to that end in the spring of 2020. The organization will aim to use technology developed by Doshisha University professor of electrochemistry Masatsugu Morimitsu and other researchers to produce the high-performance battery and put it into practical use in about three years. The development of high-performance secondary cells is indispensable for the spread of renewable energy.

Professor Morimitsu emphasized the safety and high capacity of the battery. "A zinc-nickel battery uses an alkaline aqueous solution as the electrolyte and there is no risk of it bursting into flames. Such a cell could possibly expand the capacity of secondary batteries used for hybrid cars and other devices by 1.5 to 2 times or more," he said.

The even surface of the negative electrode made of a processed zinc plate in an experimental zinc-nickel battery is seen after being repeatedly charged. (Photo courtesy of Doshisha University professor Masatsugu Morimitsu)

Materials for electrodes are key to the development of rechargeable batteries. If metal is used for the negative electrode, the capacity of the battery can be large. However, metal deposition grows like tree branches on the negative metal electrode when the battery is recharged and can touch the positive electrode, causing a short circuit. To counter this, carbon is used for the negative electrode in a lithium-ion battery.

Professor Morimitsu and other researchers used nickel for the positive electrode and zinc for the negative electrode in an experimental battery to analyze the cause of the problem, and found that the phenomenon occurs when zincate ions are unevenly distributed between the positive and negative electrodes. The research team then processed the zinc plate used as the negative electrode in such a way so that the zincate ions would not shift.

A short circuit occurred in a battery using an unprocessed zinc plate as the negative electrode after its seventh charge, but the voltage of a battery containing a processed zinc plate remained at the same level and its capacity did not decline even after it was charged and discharged 5,500 times. The team has already filed for a patent for this technology.

(Japanese original by Ryo Watanabe, Osaka Science & Environment News Department)

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