Tesla S
The critical aspects of the modern electric vehicle (EV) or plug-in hybrid electric vehicle (PHEV) are the drive system, the battery pack and the recharging system. Of course, there are other parts needed to make the vehicle function properly —the brakes, steering and suspension, for example—but the powertrain, batteries and recharging mechanism are what truly sets these special vehicles apart.
The batteries in particular represent a complex story because the technology is relatively new and it's changing so rapidly. The common belief is that there are some areas of concern revolving around battery packs—range, longevity and safety, for example. But as easy as these issues are to identify, they can be equally difficult to quantify or to answer with any degree of certainty. So we consulted an expert on the subject: Professor Linda F. Nazar, Senior Canada Research Chair at the University of Waterloo.
Should people be concerned about driving a car with a battery pack?
All commercial batteries are rigorously subjected to many safety tests. The battery pack is built to easily withstand typical wear and tear, as well as severe physical impact. There could be concerns in the event of a horrific collision, but not necessarily more so than if a gasoline tank was punctured, for example. Whenever you have a lot of energy stored, whether that is in a battery or a gasoline tank, there's going to be a safety issue.
Is there a certain form of battery that seems more likely to lead the charge in the future?
It's really too early to tell. The lithium-ion battery in the Chevrolet Volt and Nissan LEAF was considered dead territory for portable electronics back in 2000—it nevertheless has adequate capacity for first-generation systems and it's safe. The battery in the Tesla Roadster is a completely different design based on laptop batteries packed together into a single unit. Companies are starting to research generation three now, which might be lithium-sulfur batteries or one of the other five or six technologies currently being researched.
Do you see the momentum for battery development continuing?
Yes, I do think there's a great impetus. Anyone who's driven electric or hybrid cars realizes that there's a lot of potential. As scientists, we see this too, but the variable is the cost of development. In addition, we need better materials—low-cost, earth-abundant materials. It also requires an enormous amount of effort to put in place the infra-structure to support charging and to change the way people think about driving.
What can we expect from batteries in the future in terms of longevity and energy density?
One sees all the changes that are taking place, but it's difficult to say how far we can or will go until we get there. How much battery energy density will we get to in five years? It's hard to predict, but we're aiming at a factor of two to three times. I also can't say how much battery costs will drop, although they will. I am positive that there will be significant improvements—there's no way that there can't be given all the exciting new science going on at the moment.