How is a car builder supposed to "get the lead out," weight-wise, when vehicles rely on batteries (traditionally heavy lead acid ones) to supply a vehicle's many electrical needs? Up until a few years ago, lead-based batteries were the juice supplier of choice for electric cars — largely because that was all that was readily available.
Then along came nickel metal hydride (NiMH) batteries that were lighter and still capable of packing a powerful charge — and used widely in hybrid vehicles.
Automakers are placing their bets on hybrid and fully electric vehicles to help them meet government-mandated mileage requirements in the future. But even NiMH batteries lack the energy storage capacity to practically meet the expectations of consumers. It's because of a property called "energy density." For right now, batteries aren't able to hold the same energy "punch" for a given weight as fossil fuels.
Enter lithium ion batteries, which have a higher energy density than lead acid or nickel metal hydride. They've long powered cordless power tools and laptop computers, but have also suffered a nasty penchant for exploding when they got too hot. While somewhat rare, these catastrophic failures occurred often enough to prompt major concern, like when they would cause consumer laptops to catch fire. They also kept major automakers leery about putting them in mass-produced vehicles until the kinks could be worked out.
Still, companies like Tesla saw fit to put them into its fast, sleek Roadster electric sports car — which by all accounts delivered phenomenal performance.
And the time for lithium ion car batteries to go more mainstream is fast approaching. MIT researchers, for instance, found a way to slash re-charging times and make lithium ion batteries more stable (by using nickel rather than cobalt, along with the principal element lithium). This and other advancements make it appear that lightweight lithium will play a major role in helping autos keep the pounds off in the future.