Shredding old batteries can lead to a low-energy method of recycling lithium and other metals used in batteries.
Lithium-ion batteries are used in all of our personal technology, including phones, laptops, wireless headphones, and power electric vehicles. Without them our lives would be very different.
Currently, lithium in rechargeable batteries is recycled by heating to high temperatures or by treatment with concentrated acids and organic solvents. Estimates of the amount of lithium recycled vary, but calculations by lithium battery consultant Hans-Eric Melin suggest that perhaps 15% of the metal in the battery is recovered.
Oleksandr Dolotko, a materials scientist at the Karlsruhe Institute of Technology in Germany, and his colleagues used mechanochemistry (the initiation of chemical reactions by mechanical force through crushing or crushing) to recover lithium from lithium-ion batteries.
Such batteries contain lithium compounds and other metals such as cobalt and nickel. The supply of these metals has not become extremely scarce, but as battery-powered devices become more prevalent as part of the transition away from fossil fuel energy, their recycling becomes more important. The European Union has set a target of 80% lithium recovery in all batteries by 2031.
Dolotko’s team has developed two extraction methods with varying degrees of success. They first took the cathode material from a lithium cobaltate battery and combined it with an equal amount of aluminum foil. A real battery contains aluminum, which is used as a “current collector” to allow electrons to move out of the battery. The researchers mixed the compound using a grinder called a ball mill. After 3 hours, the aluminum reacted with the cathode material to produce a mixture of insoluble aluminum oxide, as well as metallic cobalt and water-soluble lithium oxide.
A separation method known as water-based leaching and further purification produces lithium carbonate, a recycled lithium compound, which can be used to make more batteries.
However, only 30% of the metal was recovered in these reactions. “Somewhere the lithium got lost,” he says Dolotko. So Drotko’s team fine-tuned the experiment. The second version involved fewer steps and heated the mixture as it came out of the ball mill with water. This prevented the formation of an insoluble lithium aluminum oxide that trapped lithium.
The team tested both processes using different cathode materials and mixtures of cathodes used in batteries. The improved process recovered 75% of the lithium from the cathode material mixture.
Mechanochemistry is not typically used in commercial chemical processes, and exactly how mechanical forces initiate chemical reactions is not fully understood, says Dolotko. “It’s really hard to say how that happens,” he says. he suggests. However, as he expected, milling made the aluminum act as a reducing agent.
This mechanochemical recycling process is a small lab-scale demonstration and a proof of principle rather than a revolutionary technology, says Circular Energy Storage, a London-based consultancy focused on lithium. said Melin, director of -Ion battery life market. He points out that battery recycling is more complex than simply developing new technology and has to do with the economics of raw materials and the adoption of battery-powered technologies such as electric vehicles.
“We are in a situation where we don’t really know today where the lithium we need in 2030 will come from,” Melin said.
Dolotko said there are opportunities to improve the process, while also working to extract other metals such as cobalt and nickel from the battery.
This article is reproduced with permission and was first published on March 29, 2022.
