Car design has gone through several iterations. First there was the chassis, then the monocoque using the body as a structural element. In the 1960s Colin Chapman popularised the engine as a structural member in racing cars. Now, with the event of EVs Chalmers University of Technology in Sweden is proposing using the battery as the major structural element.

Using “massless energy storage” cars, planes and ships, even laptops, will be lighter and energy consumption radically reduced. For example, the technology could halve the weight of a laptop, make the mobile phone as thin as a credit card or increase the driving range of an electric car by up to 70 per cent on a single charge.

The developed battery concept is based on a composite material and has carbon fibre as both the positive and negative electrodes – where the positive electrode is coated with lithium iron phosphate. The carbon fibre used in the electrode material is multifunctional. In the anode it acts as a reinforcement, as well as an electrical collector and active material. In the cathode it acts as a reinforcement, current collector, and as a scaffolding for the lithium to build on. Since the carbon fibre conducts the electron current, the need for current collectors made of copper or aluminium (for example), is reduced, which reduces the overall weight even further. Nor are any so-called conflict metals such as cobalt or manganese required in the chosen electrode design.

In the battery, the lithium ions are transported between the battery terminals through a semi-solid electrolyte, instead of a liquid one, which is challenging when it comes to getting high power and for this more research is needed. At the same time, the design contributes to increased safety in the battery cell, through reduced risk of fire.

"We have succeeded in creating a battery made of carbon fibre composite that is as stiff as aluminium and energy-dense enough to be used commercially. Just like a human skeleton, the battery has several functions at the same time," says Chalmers researcher Richa Chaudhary.

There is still a lot of engineering work to be done before the battery cells have taken the step from lab manufacturing on a small scale to being produced on a large scale, but the potential uses could see electric aviation as a step nearer and range anxiety as a thing of the past.

---