Selective Separation And Enclosed Vacuum Conversion Mechanism Of Lithium And Manganese Elements From Spent Lithium Manganese Oxide Battery

Recently,lithium ion battery-products(LIBPPs)have been widely applied with the rapid development of electrics technology and clean energy,resulting lin a sharp increase in output.The large-batch application of lithium ion battery(LIBs)leads to the mass production of spent batteries.The spent batteries not only contain valuable metals but also toxic organics.Therefore,developing an environmentally friendly way to recycle spent LIBs is of great significance for deficiency of me'tals source and sustainable development of the nation.The lab-scale and pilot-scale experiments are all performed to obtain the mixed electrode materials by mechanical treatments based on the ductility of different ingredients of spent LIBs.And the size distribution and main chemical composition of obtained materials are analyzed,The results show that the weight ratios of obtained materials are individually 32.23 wt.%and 32,67 wt.%.Then,thermodynamic analysis of obtained electrode materials is taken by thermodynamic ealculation and thermal gravlmetric experiments.And the results show that electrode materials can be effectively in situ reduced into lithium carbonate(Li2CO3)and manganese oxide(MnO)at 1073 K at enclosed vacuum conditions.Based on this,therefore,the process of recycling lithium carbonate and manganous-manganic oxide(Mn3O4)by water leaching and aerobic roasting is proposed.The carbothermic reduction conversion of electrode materials can be achieved at enclosed vacuum condition.Optimization experiments.are performed and the results show that the optimal conditions are 973 K and 30 min.91.3%of Li elements can be recovered as Li2CO3 when the roasted materials are leached three times with the ratio of solid and liquid of 50 g/L.The purity rate of Li2CO3 is 99.7%.After recovery of Li elements by water leaching,the filter residues are burned in air to fully remove graphite at optimal 1073 K for 20 min,and Mn3O4 with the purity of 96.51%is finally gained.On the basis of crystal structure of cathode materials,in which oxygen elements are packing as framework,the collapsed mechanism is proposed to explain the in situ reduction of electrode materials at enclosed vacuum condition.To prove the reliability of this mechanism,the verification experiments are carrie*d out and the results show that Li elements can be effectively rec.overed as Li2CO3 from electrode materials of LiCoOz and LiCoxNiyMnzO2 by our process.Finally,the economic assessment is taken in detail and the results show that our recycling process is positive.According to above discussions,an integrated process is proposed for the recovery of spent LIBs using mechanical separation and vacuum pyrolysis without any chemicals.The electrode materials are pre-obtained by mechanical separation and then in situ converte*d for next recycling.This process can facilitate the industrialization of recycling spent LIBs due to its excellent properties such as high handling capacity,excellent leaching selectivity and no waste liquid.