Flotation behavior of the most common electrode materials in lithium ion batteries

Abstract

Lithium-Ion Batteries (LIBs) are complex devices composed by different valuable and toxic materials. After use they are commonly sent to landfill, which represents a serious environment problem and wasteful due to the loss of valuable materials. At the same time these devices are highly demanded for the electronic and the electric vehicle industry. Therefore, recycling arises as a big opportunity in terms recovery of these valuable and scarce raw materials produced in specific areas of the world. For this reason, several processing technologies have been proposed to recover and recycle these materials from spent batteries. Amongst these, froth flotation technology arises as a cost-effective technology for the recovery of anodic graphite from cathode materials in spent LIBs due to the high natural hydrophobicity of graphite.Experiments have been carried out in a 0.5 L laboratory flotation cell to demonstrate the potential of flotation as the separation process for the recycling of spent LiB materials. These experiments have focused on the separation of the binary mixtures of the three most important commercial cathode materials (LCO, NCA and NMC) and graphite and therefore simulates a completely liberated graphite/lithium metal oxide system, where the effect of organic binding materials is not present. A range of compositions, frothing agents and both collector and no collector kinetic flotation data has been obtained.The flotation results gave a graphite concentrate with recoveries between 96.64% and 99.63% and grades between 78.13% and 90.88 %. Regarding the lithium metal oxides, these resulted in low recoveries in the concentrate between 9.47% and 16.57% and grades between 9.59% and 16.09%. A low degree of entrainment of oxide particles was achieved ranging between 0.16 and 0.29, depending on processing conditions and particle size and the best results were achieved with mixtures using NCA cathode material. These experimental results are important because they demonstrate the potential of flotation separation, but also the importance of liberation of the materials, prior to flotation.