Technology
Professor Yutaka Moritomo of Tsukuba University developed a material for the positive electrode
of lithium-ion battery that can discharge in about one second. He applied the
Prussian blue analog that allows many electrons at one time to the positive
electrode. The new material can charge and discharge at eight times higher
efficiency as compared with the existing material. Because the new material is
inexpensive and hard to deteriorate, it opened up the way for an inexpensive
lithium-ion battery. If optimal negative electrode and device are developed, a
high-speed and large-volume charging will be available for mobile phones and
electric vehicles.
The new material is
a Prussian blue compound made up of iron, manganese, carbon, and nitrogen. It
has a jungle gym structure with a grid interval of 0.5 nanometers. Because this
grid interval has a width of about five lithium ions, it allows lithium ions
goes in and out at high speed. In the experiment, a nanoparticle (with a
particle diameter of 50 nanometers) is processed to a one-centimeter-square
film and attached firmly to an electrode. After 0.01 milliampere was charged in
eight minutes, it was discharged at a time. This generated current of 85
milliampere per gram, and the discharge time was merely 1.1 seconds. Because
the new material is not an oxide, it did not deteriorate even after 30 times of
charge and discharge. The professor told that the new material has huge
potential, though it is necessary to solve the problem with heat generation in
discharge to use it for battery.
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