Energy

Battery recycling breakthrough bolsters case against heavy metals

Battery recycling breakthrough...
A new recycling technique could make a greener type of lithium ion battery even greener
A new recycling technique could make a greener type of lithium ion battery even greener
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A new recycling technique could make a greener type of lithium ion battery even greener
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A new recycling technique could make a greener type of lithium ion battery even greener
Image of a lithium iron phosphate cathode before regeneration (left) and after being treated with a new recycling technique
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Image of a lithium iron phosphate cathode before regeneration (left) and after being treated with a new recycling technique

The majority of today’s lithium batteries use a rare and expensive metal called cobalt as part of the cathode component, but mining this material comes at a great cost to the environment. One of the greener alternatives is known as lithium ion phosphate, and a new breakthrough could boost the eco-credentials of this cathode material even further by restoring it to its original condition once it is spent, using just a fraction of the energy of current approaches.

The research was carried out by nanoengineers at the University of California (UC) San Diego, and focuses on recycling techniques for batteries with cathodes made from lithium iron phosphate. By doing away with heavy metals such as nickel and cobalt, these types of batteries can help avoid the degradation of landscapes and water supplies where these materials are mined, along with the exposure of workers to dangerous conditions.

Increasing awareness of the problems associated with cobalt is driving a shift in the industry, with many looking to alternative battery designs, including big names like IBM and Tesla, who this year started selling a Model 3 with lithium iron phosphate batteries. These are safer, have longer lifetimes and are cheaper to produce, though one shortcoming is that it is expensive to recycle them once they are spent.

“It’s not cost-effective to recycle them,” says Zheng Chen, a professor of nanoengineering at UC San Diego. “It’s the same dilemma with plastics – the materials are cheap, but the methods to recover them are not.”

The recycling breakthrough focuses on a couple of mechanisms behind the deteriorating performance of lithium iron phosphate batteries. As they are cycled, this process drives structural changes that see empty spaces created in the cathode as lithium ions are lost, while the iron and lithium ions also trade places in the crystal structure. This entraps the lithium ions and prevents them from cycling through the battery.

The team took commercially available lithium iron phosphate battery cells and depleted them to half their storage capacity. They then disassembled the cells and soaked the resulting powder in a solution with lithium salt and citric acid, before rinsing it off, drying it and then heating it at temperatures of around 60 to 80 °C (140 to 176 °F). This powder was then fashioned into new cathodes and tested in coin and pouch cell batteries, where the team found the performance to be restored to its initial state.

This is because the recycling technique not only replenishes the battery’s stocks of lithium ions, but enables the lithium and iron ions to revert back to their original spots in the cathode structure. This is thanks to the addition of citric acid, which feeds the iron ions with electrons and reduces a positive charge that normally repels them from moving back to their original spot. The upshot of all this is that the lithium ions can be released and cycled through the battery once again.

Image of a lithium iron phosphate cathode before regeneration (left) and after being treated with a new recycling technique
Image of a lithium iron phosphate cathode before regeneration (left) and after being treated with a new recycling technique

According to the team, its technique consumes 80 to 90 percent less energy than current approaches to recycling lithium ion phosphate batteries, and emits around 75 percent less greenhouse gases. While this is a great start, the team says further studies are needed to ascertain the overall environmental footprint of collecting and transporting large amounts of these batteries.

“Figuring out how to optimize these logistics is the next challenge,” Chen says. “And that will bring this recycling process closer to industry adoption.”

The research was published in the journal Joule.

Source: University of California San Diego

5 comments
John Anton
This sounds promising so in a few years when they confiscate my pickup I will be able to afford batterys for my $30000. golf cart??
Karmudjun
This is a huge breakthrough! What else is under study by these folks? I don't have access to the source article so the cryptic references to the "couple of mechanisms" and the "Optimizing of the logistics" leaves me wondering if anyone is working on other approaches - possibly symbiotic - to addressing the "couple of mechanisms".

Anyway, since most golf carts use lead-acid technology, I don't think these breakthroughs will help Mr. Anton - so if the banks are confiscating (usually they repossess) anyone's vehicles, you should be able to find a lead acid battery powered golf cart at a much better rate - they can be found for less than $10,000 here in Cincinnati!
aksdad
There is nothing unethical about cobalt. It's not particularly rare and can be found all over the world. It just happens that the current largest mining operations are in the Democratic Republic of Congo where working conditions are, um, not exactly First World. It could be mined in other countries if there was enough incentive to do so.
Bruce H. Anderson
Given the appropriate mass, the lead-acid industry figured out how to recycle. I imagine that if the numbers work for this new type of electrode, it is a matter of collecting from this new batch of users, and recycling the batteries and selling them back to the same users.
John Anton
Sorry, I guess my sarcasm failed to register ? By confiscate I meant govt. Prohibiting petrol vehicles use . $30000. Golf cart to me is the electric thing that I will need to replace my truck and on further investgation the price is going to run closer to $50000. for a small commuter car .