Characterisation and recovery of metal values from spent lithium-ion batteries

Abstract

Lithium ion batteries were characterized to identify the potential of recovering metal values from these batteries. Different component parts of spent batteries of two types (M 660 and V83) were examined. The outer casings were found to be of aluminum alloy. Aluminum , lithium , copper and cobalt consisted were 45.99 percent of the total weight of the spent batteries. The rest was electrolyte solvent, adhesive and other impurity elements. In cathode electrode, lithium and cobalt constituted 7.09 and 60.24 percent respectively. LiCoO2 was the prominent phases in cathode of the spent batteries. Graphite was presence in anode of spent lithium ion battery. The proportion of aluminum in aluminum foil current conductor was determined by Atomic Absorption Spectroscopy (AAS). In the M 660 and V 83 batteries aluminum was found to be 98.90% and 98.66 % respectively and thickness of foil was 25μm. The proportion of copper in copper foil current conductor was determined by Chemical Analysis. In the M 660 and V83 LIB copper was found to be 99.06% and 98.86 % respectively and thickness of foil was 25μm In order to determine the presence of lithium and cobalt, the active cathode with foil was leached in sulfuric acid. During leaching the process parameters were kept fixed at acid concentration = 2.5M, temperature = room temperature (due to exothermic reaction), solid-liquid ratio = 1: 30 (gm/ml), time=2-5 min, and percentage of hydrogen peroxide = 5. After completion of leaching the solution was filtered this will separate the aluminum foil. Then this leach out sample was analyzed in Flame Photometer (AFP) and UV- Spectroscopy (UVS) to determine the presence of lithium and cobalt. To analyze the lithium in AFP and cobalt in UVS we had to calibrate the machine with analytical reagent lithium carbonate and analytical reagent cobalt sulfate powder according to the standard procedure. With respect to that calibration curve the presence of lithium and cobalt of spent lithium ion battery was determined. The effect of process variables, such as concentration of sulfuric acid and hydrogen peroxide and solid/liquid ratio were studied to determine the optimum conditions for this purpose. Leaching of the cathode paste was also carried out in hydrochloric acid media in presence of hydrogen peroxide as a reducing agent. Effect of process variables, such as concentration of hydrochloric acid and hydrogen peroxide, temperature, time and solid/liquid ratio were studied to determine the optimum conditions. It was found that the dissolution of LiCoO2 increased with increasing temperature, concentration of HCl, time and solid/liquid ratio (S/L) ratio. Li and Co from LiCoO2 were leached around 89% with addition of 3.5 Vol% of H2O2 as a reducing agent. VIII Kinetic parameters were established from the time versus dissolution curve using temperature as variable and keeping the other parameters fixed. Dissolution reached up to 81% for lithium and 79% for cobalt at 800C temperature within 40 minutes. Leaching behavior for both lithium and cobalt were found to follow the chemical reaction controlled process. Activation energy of lithium and cobalt were found to be 23.83KJ/mol and 27.72 KJ/mol respectively; which again justified the appropriateness of the model. The recovery products lithium carbonate and cobalt hydroxide were got by chemical precipitation with 2M NaOH at PH value 11-12. X-ray diffraction results ensure the presence of lithium carbonate and cobalt hydroxide in recovery product.