Toyota's explanation is that in spite of the higher energy density of lithium ion batteries, nickel-metal ones provide a shorter recharge time and have a greater discharge capacity, which are major advantages in hybrid vehicles. Turning to lithium ion batteries wouldn't make much of a difference in terms of performance.
"The improved efficiency from converting to lithium ion batteries from nickel-metal hydride is at best 1 percent to 2 percent in the vehicle's performance," said Shinzo Kobuki, senior managing director in charge of Toyota's battery technology, according to Autonews.
Kobuki added that lithium ion batteries will be progressively introduced throughout the plug-in hybrid and electric vehicle ranges. One reason the other companies have avoided nickel-metal batteries up until now is that they don't have the capacity to make the production cost effective, he said.
Toyota has been producing nickel-metal batteries for a decade, through its joint venture with Panasonic Corp, Primearth EV Energy CO. The company has the largest market share in the hybrid electric vehicle battery business and has been producing nickel metal-hydride batteries, as well as battery management systems for hybrids and electric vehicles since its establishment in 1996. NiMH battery modules for the General Motors 2-mode hybrids are also offered. The company was known as Panasonic EV Energy Co until 2 June 2010.
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