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Lithium-ion second-generation batteries - a stable supply of electrical power in smart houses

  • MitaCobalt-based and manganese-based? ... How are they different?
  • UtsugiSimply put, cobalt-based batteries can be made compact more easily. For this reason, they are just perfect as batteries for small mobile devices. Yet, in terms of safety, cobalt-type lithium-ion second-generation batteries were unstable. In very rare cases, they sometimes caught fire if they were recharged incorrectly or were subjected to impact. On the other hand, manganese-based lithium-ion second-generation batteries, though difficult to downsize were safer since they were less likely to catch fire. NEC opted for manganese-based lithium-ion second-generation batteries out of safety in spite of their larger size.
  • MitaWeren't you reluctant to not choose the cobalt-based batteries, which could easily be made smaller?
  • UtsugiWe weren't. However our seniors were worried and concerned about this. Even so, there was a reason why NEC continued with manganese-based batteries. We firmly believed that there would be a demand for large batteries in the future.
  • MitaWhy did you think that large batteries would be in demand?
  • UtsugiThe 90's was a heyday for mobile devices. However, on entering the new millennium, there was the issue of global warming, and everyone's concern shifted over to environmentally friendly products. As a result, ecologically friendly vehicles started to gain attention. Ms. Mita, speaking of ecologically friendly vehicles that replace gasoline-powered vehicles, what comes to mind...?
  • MitaElectric vehicles
  • UtsugiRight. You'd want batteries for electric vehicles to be large and powerful, wouldn't you? And they had to be absolutely safe since you'd be entrusting people's lives to them. This is why we considered that the spotlight would fall on large, powerful and safe manganese-based lithium-ion second-generation batteries.
  • MitaOK. I can see how this conversation is developing. The major goal was batteries for electric vehicles, wasn't it? Oh! Mr. Kawasaki, what is that?
  • KawasakiIn developing batteries, NEC first started with batteries for electric-powered bicycles. This is the actual thing. (while placing a laminate type lithium-ion second-generation battery on the table.)
  • MitaWow. It's like a boil-in-the-bag curry pack! Why did you make it this shape?
  • KawasakiBecause we could pile up lots more electrodes by making a soft sealed package like a boil-in-the bag pack rather than wrapping the electrodes in a metal tube. Lots of electrodes must be bundled together to ensure that a lot of electricity could be stored to make a powerful battery. Incidentally, the one at the bottom is the first lithium-ion second-generation battery developed by NEC to be used on electric-power assist bicycles. It's a very safe battery within the scope of not being altered. There have been no cases of users being burned or injured during regular use.

Photo: Laminate type lithium-ion second-generation battery"Laminate type lithium-ion second-generation battery" developed by NEC. In 2002, it was put into practical application as a battery for electric-power assist bicycles. (bottom battery)

  • MitaOnce it was proved to be powerful and safe, next would be batteries for electric vehicles, right?
  • KawasakiHowever, that was not the case.
  • MitaWhat? If they were safe and powerful, there wouldn't be any problems, right?
  • KawasakiThese safe, powerful manganese-based lithium-ion second-generation batteries actually had a very short life. With electric-power assist bicycles, we were able to provide batteries that users could be sufficiently satisfied with. However, when it came to vehicles that are used at full power every day for five or ten years, we could not satisfy the need with this battery.
  • MitaHow did you overcome this?
  • KawasakiThe central figure is right here, Utsugi.
  • MitaReally, Dr. Utsugi!?
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