The large-batch application of lithium ion batteries leads to the mass production of spent batteries. So the enhancement of disposal ability of spent lithium ion batteries is becoming very urgent. This study proposes an integrated process to handle bulk spent lithium manganese (LiMn2O4) batteries to in situ recycle high value-added products without any additives. By mechanical separation, the mixed electrode materials mainly including binder, graphite and LiMn2O4 are firstly obtained from spent batteries. Then, the reaction characteristics for the oxygen-free roasting of mixed electrode materials are analyzed. And the results show that mixed electrode materials can be in situ converted into manganese oxide (MnO) and lithium carbonate (Li2CO3) at 1073K for 45min. In this process, the binder is evaporated and decomposed into gaseous products which can be collected to avoid disposal cost. Finally, 91.30% of Li resource as Li2CO3 is leached from roasted powders by water and then high value-added Li2CO3 crystals are further gained by evaporating the filter liquid. The filter residues are burned in air to remove the graphite and the final residues as manganous-manganic oxide (Mn3O4) is obtained.
8 Figures and Tables
Figure 1 Schematic illustration of 18650 lithium ion batteries
Figure 2 Previous studies and our concept of in situ recycling of mixed electrode powders
Figure 3 Schematic diagram of oxygen free roasting system (1-Carbolite STF tube furnace, 2- heating rod, 3-alundum boat, 4-alundum tube, 5-power line, 6-controller, 7-inlet valve, 8-outlet valve, 9-barometer, 10-sylphon bellows, 11-vacuum pump)
Figure 4 Schematic illustration of mechanical treatment of spent LiMn2O4 batteries to gain the mixed electrode materials
Figure 6 Gas-phase equilibrium plots of (a) MnO2/C and (b) MnO2/CO
Figure 7 (a) TGA-DSC curve, (b) ion current curves of mixed electrode materials, (c) calcined mixed materials and (d) solid samples in mixed calcined materials at inclosed vacuum environment.
Figure 8 (a) Chromatogram of the gaseous sample by GC-MS and (b) XRD patterns
Figure 9 Schematic illustration of recycling valuable metals from calcine mixed electrode materials.
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