Scientists at the University of Leicester in the UK have devised a simple technique using water and cooking oil to extract valuable metals and recycle spent lithium-ion (Li-ion) batteries.
The approach allows for room temperature purification of valuable metals in a matter of minutes, a press release said.
In our bid to move away from fossil fuels and switch to greener means of transportation and energy, humanity has bet heavily on lithium-ion batteries that can store large amounts of energy.
Li-ion batteries are used everywhere, whether in electric vehicles (EVs) to support the grid or even power the phone or computer you are reading this on.
How are Li-ion batteries recycled?
Estimates suggest that 40 million EVs and over 10 billion electronic devices use Li-ion batteries. The lack of regulations around their usage means they are not designed to be recycled. Instead, crude methods involving pyro/ hydrometallurgy are used to recover important metals from them.
Once Li-ion batteries reach the end of their life cycle, they are collected and shredded into smaller pieces, forming a cake-like material called ‘black mass.’ Inside this mix is a mixture of carbon in the form of graphite, lithium, nickel, cobalt, and manganese, depending on the makeup of the battery.
In conventional approaches, a mix of temperatures and acid treatments are used to recover important metals from the mixture, which further adds to the carbon footprint of the Li-ion supply chain.
A research team at the University of Leicester found a more sustainable approach using water and cooking oil.
Sustainable, cheaper, better battery
It is common knowledge that oil and water do not mix. However, the research team involving Jake Yang used ultrasound to create nanodroplets of oil that stay inside water for weeks.
When introduced into a black mass, these nano oil droplets stick to carbon-like glue and bind the graphite particles to form a large conglomerate that floats on the water.
This leaves the valuable metals and lithium in the black mass, as the floating conglomerate can be skimmed off. Unlike conventional techniques where heat and acid lead to a degradation of the quality of the recovered material, the nano oil droplet approach allows the recovery of material in its crystalline structure. This can then be directly used in new battery cells.
The researchers have applied for a patent for this short-loop recycling approach that can make battery recycling sustainable and cheaper.
“This quick, simple and inexpensive method could revolutionise how batteries are recycled at scale,” said Jake Yang in the press release.
“We now hope to work with a variety of stakeholders to scale up this technology and create a circular economy for lithium-ion batteries.”
The team is now collaborating with researchers at the University of Birmingham to bring together other innovations in Li-ion battery recycling and test them out at a pilot facility that can process tens of kilograms of black mass per hour.
The research findings were published in the journal RSC Sustainability.
