It’s one of the dilemmas of EV design: It’s imperative to keep a vehicle’s weight as low as possible, but the most critical component – the battery – is necessarily quite heavy (and bulky). A little outside-the-box thinking yields an elegant solution – make the box the battery. In other words, design a battery material that’s strong enough to be used for structural parts.

Several great minds have already been at work on this idea. As we reported last October, Volvo and its research partners have developed a prototype energy-storage material that can be used to replace metal parts such as flooring or a trunk lid. Also in 2013, ARPA-E awarded $8.75 million to four projects to develop multifunctional structural batteries.

The latest news on this front comes from Sweden’s KTH Royal Institute of Technology, where researcher Eric Jacques says that carbon fiber can simultaneously be used as a lightweight reinforcement material for the car’s body, and as an active electrode in lithium-ion batteries.

He says carbon fiber offers a viable alternative to graphite. Lithium can be inserted into the carbon fiber microstructure, and the carbon acts as a good conductor. The carbon fiber that the KTH researchers are working with is very light and has a continuous structure and excellent mechanical properties.

“The objective of our research was to develop a structural battery consisting of multifunctional lightweight materials that simultaneously manage mechanical loads, and store electrical energy,” says Jacques. “The research project has demonstrated very good results, but we have some work to do before we can display finished batteries.”

Source: KTH Royal Institute of Technology
Image: Peter Larsson