Surface analysis of cobalt-enriched crushed products of spent lithium-ion batteries by X-ray photoelectron spectroscopy

In this work, detailed surface analysis on the fine crushed products of spent lithium-ion batteries is investigated by X-ray photoelectron spectroscopy. The results showed that although LiCoO2 was a main composition of the fine crushed products, the surface atomic abundance of cobalt was only 1.69%, but the surface atomic abundance of organic compounds was more than 75%. During the crushing process, LiPF6 decomposed and harmful and toxic substances such as HF, POF3 were generated, it is necessary to take appropriate measures to avoid the secondary pollution in the crushing process of spent LiBs. Metallics such as Co, Cu, and Al were fluoridated and oxidized, and the organic compounds were oxidized and decomposed, too. The surface composition and microstructure of the fine particles were presented, which showed that the fine particles in the crushed products were lithium cobalt oxides and graphite cores coated inside by organic compounds. Flotation test pointed out that if the outer layer was removed, the flotation selectivity would be greatly improved: the enrichment ratio could be increased from 1.16 up to 3.24. Based on the surface analysis, potential ways for removal of the outer layer were proposed. (C) 2014 Elsevier B.V. All rights reserved.