The Think City EV has a range of 160 km

Automotive and battery-industry experts, citing a lack of alternatives, said lithium-ion will be the dominant electric-vehicle battery technology for at least another 15 years.

"We now have lithium-ion and, if you look at the lead times for introducing new technology, I don't think there will be a new technology for a while," said Uwe Likar, manager advanced engineering planning at Mitsubishi Motor.

Added Jerome Perrin, r&d director at French automaker Renault: "We'll have lithium ion for another 20 years."

Both executives were speaking at the EV Battery Tech 2011 conference in London Wednesday.

Discussion at the event centered on the shortcomings of lithium-ion battery technology. Experts noted that its ability to power a vehicle for at most 160 km under ideal circumstances provides a disincentive to potential buyers.

Range anxiety, as these fears were generally referred to, is a real though mostly unfounded worry, said Chetan Maini, chief of technology and strategy at electric-vehicle maker Mahindra Reva."But when customers go to purchase an electric vehicle, it is a big issue," he added

The autonomy of electric vehicles can be extended through a range of practical measures. These include changes in driving style, adjustments of in-car systems, further technology improvements and actual changes to the batteries.

Renault's Perrin projects batteries using current technology will provide a 50 pc improvement in the independent range of electric vehicles by the end of this decade.

Executives at the conference cited many options to improve battery performance. Reva Mahindra's Maini, for example, said that optimizing airconditioning systems could yield major benefits. He also noted that keeping the battery at the right temperature "can really extend the life and performance." And he suggested using body hear at as a free in-car source of energy that could help take the strain off the car battery.

Though improvements of between 30 pc and 50 pc in battery performance can be achieved, experts agreed lithium-ion batteries will never be equal to gasoline. That's because the energy density of batteries will always be less than gasoline.

Hyundai-Kia's general manager battery system engineering, Jinho Park, said batteries'energy density has increased by about 15 pc every two years , but "now it's plateauing a little bit."

A three or four-fold improvement in lithium-ion energy density is possible, Park said, but he warned: "To match gasoline, you need 10 times the current density."

Renault's Perrin was realistic about the prospects for lithium ion. "We would like to achieve the full density of gasoline. You can dream on a bit, but it won't happen," he said.

Perrin suggested that, to solve the battery range problem, he could envision a combination of battery and fuel cell as a viable powertrain.

But he and others also expressed a general view that electric vehicles' range limitations are not a major issue because most car journeys are short. In Europe, Perrin said 87 pc of all daily trips are less than 160 km.

Mitsubishi's Likar, citing German official statistics, said 80 pc of vehicle journeys in the country are less than 40 km and 50 pc of all journies are shorter than 5 km.

-By Arjen Bongard