Cathode Scrap Research Articles

Selective recovery of cobalt, nickel and lithium from sulfate leachate of cathode scrap of Li-ion batteries using liquid-liquid extraction

This paper focuses on the extractive separation and selective recovery of cobalt, nickel and lithium from the sulfate leachate of cathode scrap generated during manufacture of lithium ion batteries (LIBs). The conditions for extraction, scrubbing and stripping of cobalt from nickel and lithium are optimized with an aqueous feed containing 25.1 g·dm−3 cobalt, 2.54 g·dm−3 nickel and 6.2 g·dm−3 lithium using Na-PC-88A. 99.8% Co is extracted with 60% Na-0.56 mol·dm−3 PC-88A in two counter-current stages at an O/A phase ratio of 3/1 and an equilibrium pH of 4.5. The “crowding effect” shown for the first time provides effective scrubbing of impurities (Ni and Li) with 2.0 g·dm−3 CoSO4 solution. The McCabe-Thiele diagram predicts the scrubbing of 99.9% Ni and 99.9% Li at an equilibrium pH of 4.75 and O/A of 2/1 in two stages. High purity (99.9%) cobalt sulfate along with Ni and Li from the leach liquor of cathode scrap is recovered by solvent extraction. The proposed process ensures complete recycling of the waste of the manufacturing process of LIBs.

Heat treatment of LiCoO2 recovered from cathode scraps with solvent method

Solvent method was used to recover LiCoO2 scrap materials, and the effects of heat treatment on the scrap materials for Li-ion battery were investigated in detail. SEM results showed that heat treatment could slightly reduce the degree agglomeration of the scrap materials. XRD results showed that the layer structure of LiCoO2 was partly destroyed during the recovery process. Low temperature heat treatment could contribute to restore the original layer structure of LiCoO2, however, high temperature heat treatment could lead to the further damage of the layer structure. Compared with the unheat-treated scrap materials, the discharge capacity and the cycle life of the pristine scrap materials heat-treated at 200 °C, 250 °C and 300 °C were obviously improved, Especially after heat-treated at 250 °C, the discharge capacity could reach about 154.6 mAh g−1 and the capacity retention rate still remained at 92.0% after 360 cycles. Particle size distribution, tap density and recovery rate of scrap materials were also investigated.

Recovery and heat treatment of the Li(Ni1/3Co1/3Mn1/3)O2 cathode scrap material for lithium ion battery

Sintering method and solvent method are used to recover Li(Ni1/3Co1/3Mn1/3)O2 scrap materials, and the effects of recovery methods and heat treatment on the electrochemical performances for Li-ion battery are investigated in detail. Among these recovered scrap materials, the unheat-treated ones with solvent method display the best electrochemical performances, the discharge capacity and the cycle life are close to that of the unused Li(Ni1/3Co1/3Mn1/3)O2 raw material. Particle size distribution, tap density and recovery rate of scrap materials are also investigated. In addition, acetylene black and Al foil can be recovered at the same time with solvent method.