Hitachi Maxell Doubles Energy Density of Li-ion Battery

Dec 29, 2015
Hiroki Yomogida
Laminate batteries developed by Hitachi Maxell. They are not based on the latest "ULSiON" technology.
[Click to enlarge image]

Hitachi Maxell Ltd announced Dec 10, 2015, that it has developed a technology to realize a lithium-ion (Li-ion) rechargeable battery with a high current capacity.

The technology can realize an energy density twice as high as that of the company's existing product by using a newly-developed silicon (Si)-based material for the negative electrode of a battery.

Hitachi Maxell plans to exhibit a Li-ion rechargeable battery using the new technology at the 2nd Wearable Expo, which will take place from Jan 13 to 15, 2016, at Tokyo Big Sight.

Hitachi Maxell calls the new technology "ULSiON." It uses "SiO-C," a composite material made by coating the surface of SiO with carbon, as a negative-electrode active material. It seems that the expansion/contraction at the time of charging/discharging, which is a problem in using Si as a negative-electrode material, was reduced to a certain level by using fine silicon particles.

"(By using the new material,) we will realize compact lithium-ion batteries that have a width of 13mm or less and an energy density twice as high as that of the existing product of the same size," the company said.

Hitachi Maxell said that it is an electrode technology to enable charging in a wide range of voltage from low to high voltages. So, the company probably expects that the discharge cut-off voltage of the battery will be as low as 2.0V

The discharge curve of a Li-ion battery using a Si-based material for its negative electrode is gentle even at low voltages. Therefore, the lower the discharge cut-off voltage, the more the capacity can be increased, improving performance.

Hitachi Maxell has already commercialized Li-ion rechargeable batteries using a Si-based material for their negative electrodes and had them employed for smartphones, etc. The company realized the new technology by using its knowledge about such smartphone batteries to improve its capacity enhancement technology, it said.

Hitachi Maxell expects that ULSiON-based Li-ion batteries will be used as laminate batteries in compact devices including wearable devices. In compact devices, only small batteries can be used. So, the company considers that there is a high demand for high-energy-density batteries.