Driving Home The Future

New battery technology for automobiles offers hope for consumers worldwide, especially with energy concerns arising from the revolution in Libya and the earthquake-tsunami in Japan.

Though better batteries are emerging as alternatives to fossil fuels, the weight and size of the batteries remain issues. Car manufacturers and scientists are developing new polymeric composites to reduce weight and free space.

The composites carry structural loads and store electrochemical energy. New electrode and electrolyte materials are being synthesized to optimize these properties.

To date, research continues on the development of solvent-free structural polymer electrolytes based on vinyl ester resins, along with carbon nanotubes. These materials exhibit a combination of strength and ion conductivity.

Using new resin electrolytes, the components are being integrated using moldable, scalable, and cost-effective processing techniques.

Cheaper Carbon Composites?

Carbon composites, extremely strong and light, are used in products ranging from tennis racquets to aircraft wings. Even some exotic cars are built with this material, but it is generally too expensive for mass-produced vehicles.

With the ability to store energy, carbon composites could become a lot more attractive for the automotive industry, according to Emile Greenhalgh of Imperial College, London.

Greenhalgh is leading the research as part of a broader European Union project studying the incorporation of different battery materials into the bodywork of cars.

The study encompasses academic and industrial partners, including the British Ministry of Defense, and Volvo (owned by Ford). The military is interested in extending the range of robotic drones and other light-weight applications.

How It Works

Greenhalgh’s material consists of woven sheets of carbon fibers which are made rigid using a resin.

To enable the material to store electrical energy, two layers of woven fibers are made into a sandwich, separated by a thin layer of a glass-based insulating material.


The resin with the carbon layers is laced with lithium ions to collect in one layer when a voltage is applied. The current flows when the sandwich is placed in a circuit. All of this is encapsulated with further layers to ensure it’s electrically isolated.

The composite behaves more like a capacitor or supercapacitor than like a battery, according to Greenhalgh.

Batteries are good at storing large amounts of charge but slow at delivering it. For capacitors, the reverse is true.


Supercapacitors have a large internal surface area which allows a large amount of energy to be delivered rapidly.

These may be used in some electric cars to provide a short burst of power for rapid acceleration. In hybrids, supercapacitors are used to recover power during braking.

To get similar characteristics from composites, the carbon fibers are first chemically treated with an alkali to create tiny pits on their surface.

This dramatically increases their surface area and the amount of charge they can hold without impairing the physical strength of the material.

Conflicting Resin Needs

Another challenge lies in resolving the two conflicting requirements of the resin.

“You want it very rigid and stiff, but from an electrical point of view you also want it to allow ions to flow through the material,” Greenhalgh says, noting with traditional resins you typically get one or the other.

Greenhalgh’s solution uses a polymer gel-based resin which combines two networks of cross-linking structure. One holds the material together and the other provides a conduit for the charged particles.

If the electrical storage composites can be boosted close to that of lithium-ion batteries, then only the roof, the bonnet and the boot lid are needed to power an electric vehicle for 130 km, according to inventor Per-Ivar Sellegren.

Sellegren, a Volvo senior engineer, is credited with the company's cutting-edge body panel battery technology.

Extended Power Factors

The composites also can be used to reduce the amount of wiring in vehicles, Greenhalgh says. The rear lights could then be powered by this material.

Compared with most rechargeable batteries, super-capacitors tend to have longer working life.

That’s an obvious benefit since most drivers of electric cars have not had their vehicles long enough to incur thousands of dollars to replace worn-out batteries.

From WMB’s vantage point, if you drive an electric car, you shouldn’t have to pay higher maintenance costs to reduce your carbon footprint.

TechMan