Thursday, July 18, 2013

No. 748: Improving the performance of a lithium-ion battery (July 18, 2013)

The electrode of a lithium-ion battery is generally a metal plate to which electrode materials are applied. Thick application increases storage capacity, but it decreases output. Professor of Tokyo Metropolitan University Kiyoshi Kanamura and Dainippon Screen jointly developed a technology to build an electrode that has a surface with tiny irregularities with the help of the ink-jet technology. They sprayed electrode materials on the metal plate and put in numerous irregularities, each of which is 70 micrometers wide and 150 micrometers high. Using the new technology, they built a lithium-ion battery with an electrode that is two times as thick as the conventional model on trial. The storage capacity doubled, but the output almost remained unchanged. That is supposedly because tiny valleys between irregularities decreased electric resistance. The new technology can be applied to various electrode materials without reducing their durability. In addition, the existing production line of lithium-ion battery can introduce the new technology with only a minor modification. (Photo: GS Yuasa's lithium-ion battery)

Professor of Tokyo University of Agriculture and Technology Katsuhiko Naoi and Nippon Chemi-Con jointly discovered that adding fine particles of nanometer size to electrode materials increases the storage capacity. Each nano particle is five to several tens of nanometers in diameter. They created these nanoparticles by reacting carbon and a metal oxide under high pressure. Used as additives, they get into the clearance between particles of electrode materials to increase the density, subsequently the storage capacity increases. It has already been conformed that adding nanoparticles to various kinds of electrode materials increases the storage capacity by 25-30%. The existing production line of lithium-ion battery can also introduce this new technology with only a minor modification. Nippon Chemi-Con already started shipping samples.

The above two technologies support the government’s plan to increase the travel distance per charge of an EV by three times to 500 km by 2030. Japan currently has nearly 50% share in the world market of materials and components for lithium-ion batteries.    

The latest model of the lihium-ion battery

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