Cooking oil used for smarter black mass recycling

Researchers in the UK have developed a technique for sustainably extracting valuable metals from battery black mass with a mix of water and cooking oil.

Scientists at the University of Leicester say their patent-pending technology allows black mass to be purified within minutes at room temperature. They use ultrasound to create nanoemulsions when the oil and water are mixed.

Oil nano-droplets purify the black mass, the mixture of carbon (graphite) and lithium, nickel and cobalt metal oxides produced when batteries are recycled. Current recycling techniques use a combination of furnace heat treatment and concentrated corrosive acids. 

‘Glue’ technique

The oil nano-droplets stick to the surface of the carbon, acting as a ‘glue’ to bind hydrophobic graphite particles together to form large oil-graphite conglomerates which float on water, leaving the valuable and hydrophilic lithium metal oxides untouched. The oil-graphite conglomerate can simply be skimmed off leaving pure metal oxides.

The University research team led by Andy Abbott and Jake Yang says the emulsion technique allows short-loop recycling of lithium-ion batteries. The battery-grade crystalline structure of the recovered material is not destroyed in the process and allows the remanufacturing of the recovered material directly back into new battery cells, unlike pyro/hydrometallurgical methods.

Expansion plans

According to Yang, ‘This quick, simple and inexpensive method could revolutionise how batteries are recycled at scale. 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 Universities of Leicester and Birmingham are also collaborating to bring together several technologies developed in a government InnovateUK funded project, ReBlend. This is creating a pilot line capable of processing black mass to demonstrate that this short loop reprocessing can function economically to provide battery grade material for new cells.