Toshiba has developed prototype batteries that can be recharged about 60 times faster than conventional lithium ion batteries, and the technology could be commercialised for portable electronics products in about three years, company executives said at a news conference on Tuesday.
Lithium ion batteries charge by absorbing ions in the negative electrode, and they discharge when ions flow from the negative electrode to the positive electrode. Conventional lithium ion batteries charge at a rate of 2 to 3 percent of their total capacity per minute and take an hour or more to fully charge, according to the company.
Toshiba's prototype batteries are lithium ion batteries that contain a material in the negative electrode that is able to absorb about 80 percent of the battery's total power capacity in about minute, according to Masayuki Ishikawa, assistant director at the company's Corporate Research and Development Center, based in Kawasaki near Tokyo.
Toshiba has developed two prototype batteries. The smaller version is 3.8 millimeters by 62 millimeters by 35 millimeters, weighs 16 grams, and has a capacity of 600 mAH (milliamp hours). The larger version is 6.5 millimeters by 110 millimeters by 70 millimeters, weighs 95 grams, and has a capacity of 3,200 mAH. The company did not disclose the voltages of the prototypes.
The smaller prototype retains 99 percent of its capacity after being charged 1,000 times, and fast-charging batteries will have about the same life as their conventional cousins, said Junichi Nagaki, a spokesman for Toshiba.
Toshiba intends to commercialise the battery technology for automotive and industrial applications in 2006, said Norio Takami, laboratory leader at the company's Corporate Research and Development Center. Next, the company is considering developing the technology for consumer electronics devices such as notebook PCs, mobile phones and other devices, he said.
"Technically, there is no problem to use this technology for cell phone batteries," Takami said.
Because the batteries charge so quickly, the company will have to develop small transformers to handle the extra current, it said.
The company has registered five patents related to the fast-charge technology in both Japan and the U.S. and it is applying for several more, Takami said.
Toshiba is also developing direct methanol fuel cell (DMFC) technology for both notebook PCs and smaller portable electronic devices. DMFCs work by mixing methanol with air and water to produce electrical power and are considered by many major Japanese consumer electronics companies as an alternative or replacement for lithium ion batteries for portable devices. A version of the fuel cell for notebook PCs is expected to be commercially available in about three years, according to Toshiba.
Toshiba believes there will be demand for both fast-charging lithium ion batteries and fuel cells, Nagaki said.