The prismatic cells used by this new battery measure 120 x 90 x 18mm, having a current capacity of 4.8Ah, an energy density of 72Wh/kg and an average voltage of 3.6V. By the end of 2009 the companies started shipping samples for auto makers. Hitachi is currently distributing the second-generation cells for the Mitsubishi Fuso Truck and Bus Corp’s hybrid buses and trucks.
Hitachi hopes that until 2010 they would mass-produce the third-generation cells with a monthly output of 300,000 units. The third-generation product is a cylindrical cell measuring 92mm in length and 40mm in diameter. It has a power density of 3,000W/kg, a current capacity of 4.4Ah and an average voltage of 3.6V.
Finally, the power density of the fourth-generation cell is 1.5 times higher than that of the third-generation product. It features a prismatic shape, having a high cooling performance and that makes it easy to expand the surface area of the electrodes.
According to Hitachi, due to the drastically enhanced power density of the fourth-generation cell, the volume and weight of batteries to be used in hybrid vehicles can be reduced by approximately 40%.