Recharging the electric car

Experimental new materials might allow the car frame to also serve as the battery.

The electric car presents engineers with a bit of a conundrum. If we want them to deliver the speed and capacity that we have come to rely on from gasoline-powered vehicles, we need to fit them with bigger, heavier, costlier batteries. These batteries then in turn take up more space, weigh the car down and demand even more power, which means the battery needs to be bigger, and so on. But a team of researchers at Imperial College in London have hit on an idea that might lead the way out of this vicious cycle and that could revolutionize the way electric vehicles run.

The key to this innovation is a new carbon-based material that is strong, light and can also store electrical power. In collaboration with nine international industrial partners, which include Greece-based INASCO, Belgium’s Nanocyl and Chinese-owned Volvo Cars, the research team is in the midst of a three-year, $5-million materials-development project. The goal with the material in question, a blend of carbon fibres and polymer resin, is to have it play a dual function. It will not only be the frame of the car, but the bodywork will also serve as the car’s rechargeable battery. The research is showing promise, and project co-ordinator, Dr. Emile Greenhalgh says the new material is revolutionary because “it does two things simultaneously — it carries a mechanical load and also stores electrical energy.”

The material is able to perform these dual tasks because of the unique combination of carbon fibre and polymer resin. The carbon fibre, similar to what you would find in the latest tennis racquets or skis, provides the structure. From there, using nano technology, the carbon fibre is combined with a multifunctional polymer resin that is capable of holding and storing an electric charge. Using polymer, as opposed to a liquid catalyst of the sort used in more traditional car batteries, allows for a gradual discharge of energy, thereby optimizing battery efficiency.

In a press release, Volvo, the only car manufacturer in the group, says the material is better at storing and charging energy than conventional batteries. Add to that the material’s strength and pliability, and it is perfectly suited for building the body panels of cars. Per-Ivar Sellegren, a development engineer with Volvo, says, “Our role is to contribute expertise on how this technology can be integrated in the future and to input ideas about the advantages and disadvantages in terms of cost and user-friendliness.” And according to Volvo, things are looking are good. A car made with the composite material would be at least 15% lighter, the expected range of the car is estimated around 130 km, and the material can be charged in two ways, by harnessing the energy generated when the car brakes or by plugging the car into an outlet.

Greenhalgh also points that the material would save on the car’s electrical wiring. As it stands now, everything is wired to just one stationary battery, whereas with the composite material any electronics could simply be encased.

At the moment, and for testing purposes only, the car’s spare wheel well has been converted using the material. Sellegren notes, “This is a relatively large structure that is easy to replace. Not sufficiently large to power the entire car, but enough to switch the engine off and on when the car is at a standstill, for instance at traffic lights.” Eventually the researchers at Imperial and Volvo want to convert the hood, doors, roof and possibly floor, but which of these parts will optimize the material’s ability to act as a rechargeable battery is still being investigated. While part of the team is working this out, another is investigating how to manufacture the material on an industrial scale, something else that has yet to be fully developed.

Imperial College isn’t letting the details prevent them from thinking big. The project is not yet a year old and already they have a patent on the material and are looking beyond automotive applications. As Greenhalgh says, “The future applications for this material don’t stop [with cars] — you might have a mobile phone that is as thin as a credit card because it no longer needs a bulky battery, or a laptop that can draw energy from its casing so it can run for a longer time without recharging.” While both Volvo and Imperial College concede that these applications are still a long way off, the potential alone is more than enough to get anyone geeked-up about the future of materials research.