Li-ion batteries in electric cars greener than believed

WASHINGTON - For the first time, researchers at Empa have made a detailed life cycle assessment (LCA) or ecobalance of lithium-ion (Li-ion) batteries, in particular the chemically improved (i.e. more environmentally friendly) version of the ones most frequently used in electric vehicles.

The investigation shows that if the power used to charge the battery is not derived from purely hydroelectric sources, then it is primarily the operation of the electric car, which has an environmental impact, exactly as is the case with conventionally fuelled automobiles.

The size of the environmental footprint depends on which sources of power are used to “fuel” the e-mobile.

On the other hand, the Li-ion battery itself has a limited effect on the LCA of the electric vehicle.

This is contrary to initial expectations that the manufacture of the batteries could negate the advantages of the electric drive.

Battery powered electric cars are often promoted as the ideal solution to the challenges of future mobility, since they produce no exhaust gases in operation.

Li-ion batteries have established themselves over competing lead-acid and nickel metal-hydride (NiMH) types because they are lighter and can store more energy.

Li-ion batteries are also basically maintenance-free, display no memory effect (loss of capacity when repeatedly charged after partial discharge), have a low self-discharge rate and are regarded as safe and long-lived.

Researchers at Empa’s “Technology and Society Laboratory” decided to find out if they are also environmentally friendly for sure.

They calculated the ecological footprints of electric cars fitted with Li-ion batteries, taking into account all possible relevant factors, from those associated with the production of individual parts all the way through to the scrapping of the vehicle and the disposal of the remains, including the operation of the vehicle during its lifetime.

The study shows that the electric car’s Li-ion battery drive is in fact only a moderate environmental burden.

At most only 15 per cent of the total burden can be ascribed to the battery (including its manufacture, maintenance and disposal). Half of this figure, that is about 7.5 per cent of the total environmental burden, occurs during the refining and manufacture of the battery’s raw materials, copper and aluminium.

The production of the lithium, in the other hand, is responsible for only 2.3 per cent of the total.

“Lithium-ion rechargeable batteries are not as bad as previously assumed,” said Dominic Notter, coauthor of the study.

The Empa team concluded that a petrol-engined car must consume between three and four litres per 100 kilometers (or about 70 mpg) in order to be as environmentally friendly as the e-car studied, powered with Li-ion batteries and charged with a typical European electricity mix.

The study has just been published in the scientific journal “Environmental Science and Technology”. (ANI)