WSJ. The Wall Street Journal reports that Toyota Motor has decided to postpone using lithium-ion battery technology in the initial versions of its next generation Prius due to worries over the safety of the li-ion technology.
The kind of lithium-ion battery technology that was under consideration for use in the Prius—one based on lithium cobalt oxide—has shown a tendency to overheat and catch on fire—a problem that has bedeviled computer makers using lithium-ion batteries made by Japan’s Sony Corp. The delay also comes in response to the recent rise in product recalls and other quality gaffes in new Toyota vehicles, the individuals who spoke on condition of anonymity said.
They said the decision was made ultimately by Toyota President Katsuaki Watanabe who in the recent past has voiced concern about Toyota’s vehicle quality—what he has repeated called the auto maker’s “lifeline.” In the U.S., the number of recalls hit 2.38 million vehicles in 2005, before settling down to 601,894 vehicles last year, according to Toyota. The company plans to use a more advanced version of nickel-metal hydride batteries for the initial launch of the next-generation Prius, people familiar with the company’s plans said.
Toyota has been working with li-ion batteries from Panasonic EV Energy, which provides NiMH batteries for Toyota’s current range of hybrids.
Panasonic EV has been working with a LiNiCoAlO2 cathode material for its next generation cells—material that is the most proven, but that also is the most thermally unstable at a high state of charge, according to Dr. Menahem Anderman of Advanced Automotive Batteries.
The material is also moisture sensitive, and experiences impedance rise at a high state of charge, he notes.
If the report pans out, Toyota’s delay may give GM an opening. Although GM has not yet selected production cells for its new Volt (or the plug-in VUE hybrid), it has awarded battery development contracts for each platform.
For the Volt, the contracts went to CPI, and to a partnership between Continental and A123Systems. (Earlier post).
A123Systems uses a doped iron phosphate cathode. Iron phosphate chemistry is the most thermally stable, and should be the most stable at high SOC, according to Anderman. CPI uses a proprietary lithium manganese spinel (LiMn2O4).
A123Systems, with Cobasys as a partner, is also involved in the VUE plug-in hybrid work, as is Johnson Controls Saft—another company working with LiNiCoAlO2.
(A hat-tip to Felix at CalCars!)