Selective liberation in dry milled spent lithium-ion batteries

Elsevier, Sustainable Materials and Technologies, Volume 23, 2020, e00134, ISSN 2214-9937
Authors: 
Samuel D. Widijatmoko, Fu Gu, Zheng Wang, Philip Hall

Lithium-ion batteries (LIBs) have an established role in the consumer electronics markets with minimum risk of replacement from any other contender in the near future. The recent momentum towards electric vehicles and the renewable energy storage market is creating an increased demand for LIBs. The large amount of hazardous waste generated from the disposal of LIBs is driving research into a sustainable approach for LIB treatment and recovery. The positive electrode active materials being the main targeted component as it is the greatest cost contributor to LIBs production. During the production of the positive electrode, a powder of active material typically Lithium Cobalt Oxide is applied to aluminium foil and held together using a polyvinylidene fluoride (PVDF) binder.

The recovery of positive electrode active material involves physical and chemical treatment. Where effective and efficient physical treatment would reduce the cost incurred for the subsequent chemical treatment. Mechanical treatment is an integral part of liberating and concentrating positive electrode active material. The positive electrode active materials have been reported are being concentrated in the finer size region. However, the cut point at which the positive electrode active material being concentrated is substantially greater than the size of the positive electrode active material particle size as found in spent LIBs.

This paper studies the characteristics of milled spent LIBs concerning particle size. The results suggest that a cut point of 850 μm gives the best composition of the positive electrode active materials recovery that minimises the involvement of copper and aluminium. However, most of the active materials are still held together by the PVDF binder that creates a substantially higher cut point proposed that the actual size of the positive electrode active material contained within spent LIBs. The interaction of copper and aluminium current collector based on size also further discussed in this paper. A comparison between selective liberation in the new and spent LIBs has been made to assess the difference in mechanical properties that contribute to its overall liberation efficiency.