Global automakers are racing to develop the next generation of energy-saving lithium-ion batteries, but Toyota has already been quietly using the technology in one of its cars in Japan — although in small numbers.
Worries about the safety of the batteries, which have had problems overheating and even bursting into flames, have been a major obstacle to introducing them in cars.
Lithium-ion batteries, already widely used in laptops and other gadgets, are considered critical in developing future electric, hybrid and other ecological vehicles because they are smaller and yet more powerful than the nickel-metal hydride batteries now used in hybrids like the Prius.