Hitachi Ltd. claims that it and its Hitachi Vehicle Energy Ltd. subsidiary have developed a lithium-ion battery having the world's highest power density for onboard applications at 4500 W/kg—1.7 times the output of the company's mass-produced, automotive Li-ion batteries. Sampling of the fourth-generation battery by domestic and overseas car manufacturers will start in the fall.
The battery employs a new manganese cathode to reduce internal resistance. An original Hitachi battery structure including thinner electrodes allows for the high output.
For the same energy storage capacity, a Li-ion battery has about half the volume and weight of a nickel metal-hydride battery and about one-third the volume and weight of a lead-acid battery, according to the company.
In 2000, the Hitachi Group used its technological and manufacturing capabilities in fields ranging from materials to battery-control systems to develop and mass-produce what it calls the world's first safe, high-performance, long-operating-life Li-ion battery for automotive applications. The company says its second-generation Li-ion battery with a power density of 2600 W/kg currently being delivered for automotive and railway applications is the world's only mass-produced one for onboard applications. So far, about 600,000 cells have been delivered, mainly to car manufacturers and railway companies.
Development of a third-generation battery with a power density of 3000 W/kg has been completed and will go into mass production in 2010, with deliveries later the same year.
In addition to its lineup of stand-alone battery cell products, Hitachi plans to develop battery system solutions that include control systems.