TOKYO Toshiba Corp. has developed a lithium-ion battery the company said features the short rechargeable time of capacitors and the energy capacity of conventional lithium-ion batteries.
Toshiba's new battery can recharge 80 percent of the battery's energy capacity in one minute, approximately 60 times faster than the typical Li-ion batteries. The energy density is 150 to 250 Wh (Watt-hour)/liter, equal to the lower range of energy densities existing lithium ion batteries have. Advanced Li-ion rechargeable batteries reach densities of 600 Wh/l.
"It should be the world first lithium ion battery that can be charged in one minute. The battery has a big potential. It could be used for mobile phones in the future, but we put the priority on applications such as automobiles that require quick recharging time and large cycle time," said Norio Takami, Laboratory leader of Advanced Functional Materials laboratory at Toshiba's Corporate Research and Development Center.
Toshiba's prototype battery has a capacity of 600mAh and measures.8mm thick, 62mm high and 35mm deep. It was demonstrated in hard disc music player for about 10 minutes by charging 5 milliwatts in 5 seconds.
According to Takami, the battery shows less than 1 percent deterioration in capacity after 1,000 cycles of discharging and recharging.
The battery employs a cobalt-based anode and a non-carbon material cathode in place of carbon material that is used for conventional lithium ion batteries, but Toshiba calls it a lithium ion battery because the electric charge movement depends on lithium ion.
Toshiba achieved the breakthrough by using nanoparticles of several hundred nanometers coated uniformly on the negative electrode and newly developed electrolytic solution. This stable formulation does not react with lithium ions at the cathode in a manner that would lower the battery's cycle time. The electrolytic solution and nanoparticles enable large number of lithium ions move quickly to the cathode and store in the particles in recharging mode.
With the stable electrolyte solution, the battery discharges 80 percent of its capacity at minus 40 degrees centigrade, compared to 100 percent discharge at 25 degrees centigrade for conventional Li-ion batteries. In the high temperature operation, Toshiba reported that the capacity deteriorates by only 5 percent at temperatures of 45 degrees centigrade after 1,000 cycles of discharging and recharging.
The battery's voltage, which Toshiba did not disclose, is lower than the 3.6 volts of present lithium ion batteries.
Toshiba plans to begin mass producing the battery in its fiscal 2006 ending March 2007. Producing the battery may be complicated, however, by Toshiba closing its Li-ion battery subsidiary AT Battery last December, and selling the battery plants to Sanyo Electric Co. Ltd. last summer. Toshiba is now determining how to commercially produce the battery.
