With all the attention paid to electric cars, you’d think they’d be common on the roads by now.
The major holdup isn’t the car, but the battery: It hasn’t been easy to find the right combination of power, weight and cost.
Lithium-ion batteries are the best choice right now, says Tom Baloga, vice-president of engineering for BMW North America. The company uses lithium-ion units in its ActiveHybrid 7 sedan.
“We have seen them in consumer electronics, and lithium-ion is taking over from other types of batteries for power tools,” Baloga says. “Even though they are expensive, lithium-ion is the choice for battery electric vehicles.”
Less-expensive nickel metal hydride (NiMH) batteries are currently used in hybrid vehicles, including BMW’s ActiveHybrid X6, but lithium-ion is expected to replace these bulkier, less-effective batteries. “The X6 was developed years ago, at a time when there was uncertainty about the safety of lithium-ion batteries,” Baloga says. “Now there are several layers of redundancies in failsafe protection. The temperature of the battery is very closely monitored, and in the event of a short circuit, it shuts down the battery.”
Baloga also says that concerns over the supply of lithium, a rare-earth element, are unfounded.
“The consensus is that there is about 30 million tonnes of lithium supply in the world,” he says. “If you assume that each battery uses about four kilograms per vehicle, that is enough lithium right now for seven and a half billion all-electric cars. That’s 150 years of car production for the whole world.
“Recycling is also a critical aspect of any kind of battery that we have. Lithium-ion batteries will be highly recycled and the lithium can be used in other batteries, and that will further reduce the strain on the supply.”
Before they’re recycled, though, the batteries will probably have a secondary life: when they’re no longer capable of powering a car, they can be used for stationary storage. “Energy companies are interested in using them for managing the power output to balance the grid,” Baloga says. “They’ve got a life even before they go to the recycler. This has to all work together to reduce the initial cost. It’s expected in future that customers might lease batteries as opposed to buying them outright.
“There’s a lot of research going into new batteries, but I’m not aware of anything that looks more promising than lithium right now.”
