Separation of Lithium Ion Cathode Material for Direct Recycling

In recent years there has been an acceleration in the use of lithium ion batteries (LiBs) in applications ranging from automotive to wearable technology. This means it is now more key than ever to be able to extract maximum use and then to recycle these batteries in a safe sustainable manner as they not only contain rare and critical elements but many of these elements are expensive and environmetaly damaging to extract and make into batteries and thus can cause a large amount of environmental damage¹. A good way to prolong the life of some LiBs is to utilise them in 2nd life applications without any chemical treatment. 2nd life applications vary and can range from electric vehicle fast charger support^2,3 to back up power⁴ and grid balancing support^2,5, these 2nd life applications can extend the life of a battery by anywhere between 6 and 30 years².

Some batteries may not be re-used directly in second life applications due to capacity loss through degradation. Degradation can occur through a number of mechanisms including: electrolyte decomposition⁶, Loss of active lithium, and loss of active material porosity and interconectivity⁷, all of which lead to an increased impedance and losses in efficiencies. For these batteries a disposal route must be found. Currently for End of Life (EoL) batteries the disposal routes most commonly consist of either stock piling, which may be a potential environmental hazard, or pyrometallurgical processes that are not as environmentally friendly and do not necessarily recover the maximum value from the product. For quality control rejects no dedicated commercial recycling process is known about. One of the main hurdles to direct recycling of LiBs is the difficulty in separating active material from casing and current collector.

In this work we investigate how two different commercial cathode chemistries are affected by two separation methods and compare these to their untreated equivalents. The first method comprises of an acid and ultrasonic agitation and the second comprises of the green solvent DMSO and ultrasonic agitation. We present data to investigate how particle morphology, crystal structure and metal content varies between the three methods. We then go on to remanufacture the materials into half cells and examine the capacity, electrochemical performance, and cycle life of the two processes.

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