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

Utsugi

No, no. It was realized with the cooperation of various people, you know. When batteries are repeatedly recharged and discharged, the manganese electrodes soon get weak. And before long, the electrolytic solution inside dries up. However, we added a "certain substance" to this solution. This substance protects the solution and turns into a protective film. As a result, the life of the solution was dramatically extended.

Kawasaki

Although Dr. Utsugi mentions this as if it were an everyday phenomenon, NEC made such a breakthrough discovery that this has been patented. As a result of Dr. Utsugi's discovery, the life of these batteries was instantly extended and they came to be adopted in electric vehicles. By the way, the lithium-ion second-generation battery mounted on the Nissan Leaf electric vehicle was jointly developed by NISSAN MOTOR CO., LTD. and NEC.

Mita

So, that's what happened! By the way, about how long is the life of NEC's lithium-ion second-generation batteries?

Kawasaki

They are designed to have sufficient remaining battery capacity even if used continuously for a long time. With the latest prototypes, the number of years taken for rechargeable battery capacity to fall to 70% of initial capacity is about 13 years and to about 50% is about 33 years. This means that battery life is double that of conventional batteries. However, these are still the results of simulation. After all, lithium-ion batteries came into being about 25 years ago.

Mita

So, this is why manganese-based lithium-ion second-generation batteries came into the spotlight.

Kawasaki

Yes, that's right. Even though the Nissan Leaf has been put on sale, as you might expect, the mainstream lithium-ion second-generation batteries were still small cobalt-based batteries. However, this situation changed completely after the great earthquake in 2011. A great deal is now expected of manganese-based lithium-ion second-generation batteries.

Mita

What do you mean?

Kawasaki

As everyone knows, after the earthquake, the stable supply of electrical power was difficult and this became a national energy issue to be tackled by the whole country. A realistic solution is to popularize "storage systems" whereby electrical power generated from sunlight, wind power, thermal power and other power sources is stored in large batteries and is transferred when it is required.

Mita

Come to think of it, smart houses being talked about right now use these storage systems, don't they?

Utsugi

Yes, that's right. Smart houses use household storage systems. We have already commercialized these household storage systems and have started sales via housing manufacturers and building material trading companies. In the future, they will be bigger. We are working towards larger scales such as one entire city.

Mita

At a scale of a whole city, you will need really large storage batteries, won't you? Oh ... I see!

Kawasaki

Yes. And, what is attracting attention are manganese-based lithium-ion second-generation batteries that can be made large and that are capable of storing a lot of electrical power.

Mita

So, manganese-based lithium-ion second-generation batteries will be "big storage batteries" then.

Utsugi

Yes, exactly. Right now, we are proceeding with a project that involves joining lithium-ion second-generation batteries together so that a whole city will operate as if it were a single giant storage battery. Besides this, we are moving ahead with various R&D programs at a feverish pace towards the realization of storage systems.

Kawasaki

Frankly speaking, the anticipation we are feeling right now is bewildering. However, it's our intention to keep on working for everyone so that storage systems can be put into practical application as early as possible.

Mita

Please, keep up the hard work! Thank you for your great talk today!

Utsugi, Kawasaki

Thank you very much.

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