New lithium-ion battery recycling method that’s energy efficient and needs no added chemicals
A lithium-ion battery is difficult to beat due to its high energy density and working voltage. However, current recycling requires temperatures above 1000°C or corrosive chemicals, as well as a significant amount of work sorting the batteries and excess waste before and after the lithium is extracted.
However, a group of German researchers has developed a low-temperature recycling method for lithium-ion batteries that requires only a small amount of aluminium and water. There’s also a ball mill.
“This method is expected to increase efficiency at a large scale, foster environmental sustainability, and reduce the overall cost of the lithium-ion battery recycling process,” says Dr. Oleksandr Dolotko, a researcher at the Karlsruhe Institute of Technology, Germany, and lead author on a paper describing the research, published in Communications Chemistry.
“Currently, we achieved up to 70% of lithium recovery on the laboratory scale.”
It’s a “universal” method, according to the researchers, and it could work on any lithium-ion battery.
The method employs “mechanochemistry,” which is the use of mechanical energy to initiate a chemical reaction. A ball mill is a common method for grinding the reagents.
“Mechanical treatment (or ball milling) is already used in battery recycling technologies, but only for crushing electrodes during the ‘black mass’ preparation,” says Dolotko. (The ‘black mass’ is what batteries are processed into before recycling.) “We believe that until now, the ability of mechanochemistry is not used in recycling technologies to its full potential.”
In lithium-ion batteries, lithium is bonded to oxygen as well as a variety of metals such as cobalt, manganese, nickel, and iron.
The researchers discovered that when these compounds were ball-milled with aluminium, the aluminium acts as a “reducing agent” on the other metals, separating them while sticking to the lithium and oxygen.
When gently heated with carbon dioxide and water, it transforms into lithium carbonate, which is the compound used to make lithium-ion batteries in the first place.
Dolotko points out that, because battery cathode foil typically contains some aluminium, the process doesn’t require any additional chemicals other than carbon dioxide and water.
Once the lithium has been extracted, they can recover the other metals from the powder produced by the ball mill.
“Their recovery is significantly simplified after the mechanochemical reduction reaction,” says Dolotko.
This is because the aluminium has “reduced” them, a process that normally requires more heat and acid. Scientists are currently working on a method to process all of these non-lithium metals.
Because the process is simple, the researchers believe it should be simple to implement on a large scale.
“Currently, we are taking part in two European consortia where this technology will be applied to industrially treated lithium-ion battery wastes, scaled up, and evaluated for its profitability and environmental impact,” says Dolotko.
“As inventors, we believe adopting this technology in the industry is real and achievable. Especially if we take into consideration that lithium-ion battery recycling technology is still in its infancy.
“One of the most challenging parts of the invention is finished – the technique works. Now it is time to bring it to another level, which is our next exciting step.”
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Content Credit: COSMOS