Battery breakthrough may solve electric car dilemma
The promise of a global electric vehicle transformation has a looming problem. The cathodes in the lithium ion batteries typically used in electric vehicles, or EVs, are made of metal oxides that contain cobalt, a metal found in finite supplies and concentrated in one of the globe’s more precarious countries.
But an assistant professor at the University of California San Diego says he has developed a way to recycle the used cathodes from spent lithium ion batteries and restore them to the point where they work as good as new one.
‘‘Yes, it can work effectively,’’ said Zheng Chen, who works as a nano-engineer at the Sustainable Power and Energy Centre at the university’s Jacobs School of Engineering.
The method also works on lithium cobalt oxide, which is widely used in electronic devices such as smartphones and laptops.
‘‘In my house I have about six cellphones,’’ Chen said. ‘‘I have probably about five laptops. They all have lithium batteries. I thought, there is no clear system to recycle and retrieve them.’’
The process takes degraded particles from the cathodes found in a used lithium ion battery. The particles are then pressurised in a hot, alkaline solution that contains lithium salt. Later, the particles go through a short heat treating process called ‘‘annealing’’, in which temperatures reach more than 760 degrees C.
After cooling, Chen’s team takes the regenerated particles and makes new cathodes. They then test the cathodes in batteries made in the laboratory.
The results, Chen says, have been impressive. The new cathodes have been able to maintain the same charging time, storage capacity and battery lifetime as the originals did.
‘‘I admit I was surprised it became so effective, because originally I thought we couldn’t get all this performance back, that we would lose 10 per cent or 20 per cent,’’ he said. ‘‘But it turns out we’re getting exactly the same performance.’’
Details of the recycling method were recently published in the research journal Green Chemistry, submitted by Chen and two colleagues.
Now that the method has been established in the lab, the goal is to optimise the process so it can be economical on an industrial scale.
Right now, the particles have to be picked out manually from the old, conked-out battery. The entire cycle took about 10 hours to complete, Chen said. Researchers are working on a way to simplify and accelerate the process.
Less than 3 per cent of lithium ion batteries around the world were recycled. Chen said. The batteries from used smartphones and laptops often end up in landfills or tucked away in drawers and wardrobes.
But the lithium ion batteries in EVs are much larger, thus producing a long-term challenge as the zero-emissions sector grows and policymakers seek a way to transition away from cars and trucks powered by fossil fuels.
It is harder to recycle the batteries found in EVs than the leadacid batteries used in petrol- or diesel-powered vehicles, because of the number of materials involved and differences in how manufacturers build them.
About 54 per cent of the world’s cobalt supply comes the Democratic Republic of Congo, which has suffered through two violent civil wars in its relatively short history. Human rights groups have documented how child labour is sometimes used to extract the metal, which is a byproduct of mining nickel and copper.
There is also a finite supply of lithium, with Bolivia estimated to possess about half of the world’s supply.
Finding a way to recycle lithium ion batteries on a large scale could greatly reduce the demand for cobalt in electric vehicles, as well as curbing the rising cost. It could also help to alleviate the environmental concerns surrounding ageing batteries in smartphones, laptops and other digital devices, as well as EVs.
‘‘The commercial application is huge,’’ Chen said.