It is a component of electric car batteries, whose recycling will be essential in the coming years.
Graphite accounts for up to a quarter of the weight of these batteries, yet no one had really looked at how to recycle it, says the 29-year-old, who was awarded last year's European Institute of Innovation and Technology (EIT) prize for her discovery.
"Battery manufacturers were not interested in it because they could get them at low cost in China," adds the Frenchwoman.
At the prestigious German research institute Helmholtz in Freiberg (eastern Germany), she developed a method to separate graphite from the metals contained in the "black mass", a black powder also composed of cobalt, nickel, lithium and manganese.
"We put the +black mass+ in the water and inject reagents and air bubbles, like in a jacuzzi. Graphite attaches to these bubbles, while metals are hydrophilic and therefore remain in water," explains the researcher.
Anna Vanderbruggen also works as a consultant for industrialists. They are only beginning to organize themselves for the gigantic challenge that the end of life of electric car batteries will represent.
"Market under construction"
Tensions over the supply and cost of raw materials have sharpened their interest.
The price of lithium has increased 13-fold over the past five years, said Philippe Barboux, a chemistry professor at PSL University in Paris.
French researcher Anna Vanderbruggen holds a basin of dark, bubbling liquid, the result of a process developed to recover graphite from old lithium-ion batteries in a laboratory at the Helmholtz Institute in Freiberg, eastern Germany, February 27, 2023 © JENS SCHLUETER / AFP
"It's a material that we didn't recycle because it wasn't cost-effective," he says.
Some 350 million electric cars are expected to be on the world by 2030, up from 16.5 million in 2021, the International Energy Agency (IEA) predicts.
"In ten years, we will be making so many batteries that we will absolutely have to recycle lithium. Otherwise, there will not be enough," warns Mr. Barboux.
In theory, manufacturers are now able to recycle almost all the materials that make up batteries, according to experts interviewed by AFP.
Germany's Aurubis Group, one of Europe's largest producers of non-ferrous metals, claims to be able to recycle at least 95% of the metals contained in the "black mass" at its pilot plant in Hamburg. An objective also shared by the French mining group Eramet, the Belgian Umicore and the German car manufacturer Mercedes.
But most of the current projects are still in the pilot phase.
"It's a huge market under construction and we want to play a part in it," Ken Nagayama, head of battery materials development at Aurubis, who is currently working on a graphite recycling process, told AFP.
He believes that "the market should be sufficient to develop an industrial-scale battery recycling plant in the second half of the decade".
There are not yet "enough volumes of batteries at the end of their life for the moment," says Serge Pelissier, director of research at the Gustave Eiffel University in Lyon, while batteries can last at least 7 to 8 years according to him.
The different models of existing car batteries also complicate the implementation of standardized recycling, as for phones and laptops that already have a well-established sector.
French scientist Anna Vanderbruggen shows the result of grinding a lithium-ion battery containing aluminum foil, copper sheets and particles in the upper part of the pot, and the "black mass" with graphite, cobalt, nickel and manganese at the bottom, in a laboratory at the Helmholtz Institute in Freiberg in eastern Germany. February 27, 2023 © JENS SCHLUETER / AFP
"We will have to wait until the early 2030s" for the market to be mature, predicts Alex Keynes, of the NGO Transport & Environment.
The Swedish and Norwegian joint venture Northvolt–Hydro is a pioneer in this niche. It advances the goal of recovering the equivalent of 500,000 batteries by 2030.
The European Union is also putting pressure on it. According to an agreement reached in December 2022, electric vehicle batteries must, from 2031, incorporate 16% recycled cobalt as well as 6% recycled lithium and nickel.
In addition, manufacturers will have to recycle at least 70% of battery weight before 2031.
"If they recover new components such as graphite, they will be able to meet these requirements," says Anna Vanderbruggen.
© 2023 AFP