Black mass, the residue from discarded lithium-ion batteries, is a growing problem for the recycling industry. Globally, there are an estimated 40 million electric vehicles (EVs), and approximately 10 billion active mobile phones, laptops and tablets powered by lithium-ion batteries.
However, the lack of regulations means lithium-ion battery packs are not designed to be recycled. The reason is that it is complicated and expensive to recover the valuable metals and minerals from the low-value battery scrap. But now a group of researchers at the UK University of Leicester have developed a patent-pending method for sustainably extracting valuable metals from a waste battery product with a mix of water and vegetable oil within minutes of operation at room temperature.
The research team led by Professor Andy Abbott and Dr Jake Yang at the University of Leicester, working under the Faraday Institution’s ReLiB project, found an innovative way of recovering valuable battery-grade metal oxides from crushed batteries. The secret formula was to use nanoemulsions created from a trace of vegetable cooking oil in water.
Ultrasound can create nano-droplets of oil, stable for weeks. They are found to purify battery waste containing a mixture of carbon (graphite) and valuable lithium, nickel and cobalt metal oxides (NMC). 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.
Dr Jake Yang from the University of Leicester School of Chemistry said: “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.”
Picture: Under a microscope the valuable metal oxide can be seen as white spheres whereas the black spheres are graphite. The nanoemulsion enables the graphite to float while the metal oxide sinks.
