Toyota Motor Corp delivered a lecture on the development of its lithium-ion (Li-ion) battery at the 3rd Int’l Automotive Electronics Technology Expo, which took place from Jan 20 to 22, 2010, in Tokyo.
Taketoshi Minohara, general manager of Toyota’s Hybrid Vehicle Material Engineering Division, explained the company’s efforts to develop Li-ion batteries after mentioning its environmental activities and the evolution of nickel-metal hydride batteries.
Toyota first applied its Li-ion battery to the idling stop model of the Vitz compact car, producing 4,900 units from February 2003 to December 2008. The current production volume is 60 to 100 units per month. The unit consists of four cells whose voltage, current capacity, output density and energy density are 3.6V, 12Ah, 2,250W/kg and 74Wh/kg, respectively.
At the end of 2009, Toyota started to equip the Prius Plug-in Hybrid with its Li-ion battery being developed for hybrid vehicles. Though Minohara did not disclose the details of the battery, the company had tested its durability for three years in five countries by using real cars before it was mounted on the vehicle, he said.
In Japan, the US, Canada, Germany and Spain, the total running distance of 150 test vehicles added up to about 10.5 million kilometers. The car that had the longest running distance traveled 574,000km in the US. On the other hand, one of the test vehicles traveled only several hundred kilometers because Toyota assumed a case where the vehicle is almost always parked.
By testing batteries in the temperature ranging from -30 to 40°C, Toyota developed a Li-ion battery that can withstand any usage, Minohara said. As for the deterioration of the battery, the company evaluated the internal resistance by driving test vehicles more than 500,000km and for three years and found no significant change in it, he said.
Toyota is now planning to reduce the cost of the battery and apply it to next-generation electric vehicles and personal mobility vehicles. The company aims to mass-produce such electric vehicles in about 2012. In regard to the development of the battery, he said, “First, we will try to find the limitations of existing technologies. Then, we will overcome those limitations by using knowledge in the field of science to develop an ultimate battery.”
Source: nikkeibp.co.jp
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