Could a tool from the dentist's office lead to better recycling of lithium-ion batteries?
Researchers from the University of Leicester, led by Professor Andrew Abbott, are using ultrasound to separate out valuable materials from electrodes so that the components can be fully recovered from batteries at the end of their life.
The efforts are part of Abbott's group, The Faraday Institution , which aims to accelerate new developments in batteries.
How Lithium-Ion Batteries Are Recycled
Current recycling methods for lithium-ion battery recycling typically feed end-of-life batteries into a shredder or high-temperature reactor. That kind of energy-intensive setup requires a complex set of physical and chemical processes.
Abbott and his team want to disassemble, not shred, the batteries. Disassembling a battery allows more parts to be recovered, and in their purest forms, according to Abbott and the team.
The ultrasonic delamination technique effectively "blasts" the active materials from the electrodes, leaving virgin aluminum or copper. The process proved highly effective in removing graphite and lithium nickel manganese cobalt oxides, commonly known as NMC.
The research has been published in Green Chemistry , and the researchers have applied for a patent for the technique.
“This novel procedure is 100 times quicker and greener than conventional battery recycling techniques and leads to a higher purity of recovered materials," said Prof. Abbott in a recent news release .
According to the study, the ultrasound disassembly of lithium-ion batteries recovered about 80% of the original material.
“It essentially works in the same way as a dentist’s ultrasonic descaler, breaking down adhesive bonds between the coating layer and the substrate."
The researchers are in initial discussions with several battery manufacturers and recycling companies to place a technology demonstrator at an industrial site in 2021, with a longer-term aim to license the technology.
The team hopes that the technology will be used initially to feed recycled materials straight back into the battery production line.
In a short Q&A with Tech Briefs below, Abbott explains more about what that recycling process might look like.
Tech Briefs: The recent news release from the University of Leicester says that your method "effectively blasts the active materials .” What does that involve exactly? That sounds intense (and difficult?). Can you take us step-by-step through the process?
Prof. Andrew Abbott: The process is relatively low energy. Ultrasound causes bubbles which implode when they hit a surface, causing soft layers on a surface to fracture and break away from the surface. The process is shown schematically in the infographic above. You can also watch the process in action here , along with a fast frame speed video that shows the active layer fragmenting from the surface.
Tech Briefs: Can you take us through what's happening in this video here?
Abbott: In the video the composite electrode is being fed through on the right of the frame and the metallic current collector is recovered on the left. The active material is filtered off from the liquid in a continuously circulated bath. In the video we use a graphite coated copper anode, just to show the contract between the copper and graphite. It works equally well for the NMC-coated aluminum cathode but there is less of a visual contrast.
The ultrasonic wave generated by the horn in the center of the frame breaks the adhesive bond between the copper and the graphite/polymer layer, enabling the samples to be separated. Initially, the processed is aimed at production scrap, but it works equally well for end-of-life cells. The electrodes fed through in the video are production scrap. The metal would need to be remelted and rolled and the active material can be reused if it has not been cycled.
Tech Briefs: What inspired you (and your team) to try this “dentist-like” approach? Is this approach considered an unconventional one?
Abbott: When we started to characterize the mechanical properties of the active layer on the electrode, we found that the adhesive bond was relatively weak so we thought that ultrasound may be useful if we could target it to break the bond between the active layer and the substrate.
Tech Briefs: What are you working on next, and what is most exciting to you about this work and its possibilities?
Abbott: We are working on cell design and novel binders which make the active layer easier to remove. We would like to develop a recycling process which opens the cell safely and separates the anode from the cathode.
What do you think? Share your questions and comments below.