Batteries seem to be the limiting factor in the popularity of electric cars. They are one of the most expensive components of the vehicle, and have limited range compared with gasoline powered vehicles. While there have been some impressive advances in recent years, a team of researchers have created a supercapacitor film that could replace the need for a battery altogether within the next five years. The collaboration between scientists at Rice University and Queensland University of Technology resulted in two papers, published in Journal of Power Sources and Nanotechnology.

The supercapacitor consists of two layers of graphene with an electrolyte layer in the middle. The film is strong, exceedingly thin, and is able to release a large amount of energy in a short amount of time, which is essential.

"Vehicles need an extra energy spurt for acceleration, and this is where supercapacitors come in. They hold a limited amount of charge, but they are able to deliver it very quickly, making them the perfect complement to mass-storage batteries," Marco Notarianni of QUT said in a press release. Notarianni was lead author of the Nanotechnology paper. "Supercapacitors offer a high power output in a short time, meaning a faster acceleration rate of the car and a charging time of just a few minutes, compared to several hours for a standard electric car battery.”

Ordinary batteries take up a large amount of space, whereas the supercapacitor film could be integrated into multiple areas of the vehicle, such as the body panels, roof, floor, and doors. A supercapacitor this large could provide the vehicle with the amount of energy it needs, while making the vehicle itself much lighter.

The graphene-based supercapacitor film would be able to be fully charged in a matter of minutes, rather than the several hours it takes for a conventional battery. But while it might charge and release energy faster than standard batteries, they currently don’t hold nearly as much energy. This is one aspect that the scientists hope to change with further study.

"In the future, it is hoped the supercapacitor will be developed to store more energy than a Li-Ion battery while retaining the ability to release its energy up to 10 times faster - meaning the car could be entirely powered by the supercapacitors in its body panels,” added co-author Jinzhang Liu. "After one full charge, this car should be able to run up to 500km (310 miles) - similar to a petrol-powered car and more than double the current limit of an electric car.”

Because the supercapacitors are made out of graphene, a layer of carbon only one atom thick, the film is a more ecological choice. Additionally, because carbon can be sourced more easily than the lithium found in conventional batteries, it could end up being fairly economical as time goes on and production becomes more widespread.

"The price of Li-Ion batteries cannot decrease a lot because the price of Lithium remains high. This technique does not rely on metals and other toxic materials either, so it is environmentally friendly if it needs to be disposed of,” explained lead researcher Nunzio Motta.