Selective Extraction Of Lithium From Spent Ternary Cathode Materials By Sulfation Roasting And Water Leaching

With the development and popularity of energy vehicles（EVs）,the challenge for lithium salts between the increasing demand and insufficient supply is grown prominently,which further restricts the development of lithium-ion batteries（LIBs）.Recycling spent LIBs and re-extracting lithium are regarded as the effective strategy to solve above contradiction.Whereas existing regeneration technologies focus on the recovery of nickel and cobalt,neglecting the serious loss and low recovery efficiency for lithium in the lengthy hydrometallurgy process and high-temperature pyrometallurgy process.Herein,this paper proposed a consecutive sulfation roasting and water-leaching process to selectively reclaim lithium from spent LIBs cathode materials,which shortens the recovery process,increases the lithium recovery efficiency,and realizes the efficient and value-added utilization of lithium.This strategy can provide reference for the research of recycling lithium from spent LIBs.The detailed contents are as follows:Specifically,the spent LiNi_1-x-yCo_xAl_yO₂（NCA）material and sublimated sulfur were disposed of by sulfation roasting and water-leaching process to efficiently separate Li（Ⅰ）and Ni（Ⅱ）,Co（Ⅱ）from the mixed material.A detailed thermodynamic calculation and a series of characterization analyses were conducted to reveal the conversion of metal elements in the sulfurization process,elucidating the mechanism of selective lithium extraction.The results display that the NCA materials were transformed into water-soluble Li₂SO₄ and insoluble Ni-Co metal oxides via reacting with sublimated sulfur in an anaerobic atmosphere.To explore the optimal experimental conditions,selective extracting experiments of lithium under different experimental parameters were conducted.Under the conditions of a roasting temperature of 800 ^oC,roasting time of 360 min and raw material mass ratio（NCA:S）of 5:3,the lithium leaching efficiency could reach the peak（98.52%）,accompanied by a low leaching effect of nickel and cobalt.Finally,a high purity（98.50%）of regenerated Li₂CO₃ was prepared from the lithium-contained leaching solution,and was further resynthesized as Li Ni_0.6Co_0.2Mn_0.2O₂materials via roasting with Ni_0.6Co_0.2Mn_0.2（OH）₂ precursor.The electrochemical test indicated that resynthesized Li Ni_0.6Co_0.2Mn_0.2O₂materials have an excellent discharge capacity of 156.71 mAh/g at 0.1A/g,and a outstanding cyclic stability（131.45 m Ah/g after 100 cycles at1 A/g）.Specifically,the spent LiNi_1-x-yCo_xMn_yO₂（NCM）material and sublimated sulfur were disposed of by sulfation roasting and water-leaching process to extract Li（Ⅰ）from the mixed material efficiently.A detailed character analysis of different materials in the roasting process was conducted to reveal the conversion mechanism of metal elements in the roasting process,indicating that the NCM materials were transformed into water-soluble Li₂SO₄ and insoluble Ni-Co metal oxides via reacting with sublimated sulfur in an aerobic atmosphere.To explore the optimal experimental conditions,selective extracting experiments of lithium under different experimental parameters were conducted.Under the conditions of roasting temperature of 800 ^oC,roasting time of 360 min and raw material mass ratio（NCM:S）of 5:1,the lithium leaching efficiency could reach a peak（97.86%）,accompanied by a low leaching effect of nickel and cobalt.Finally,a high purity（98.80%）of regenerated Li₂CO₃ was prepared from the lithium-contained leaching solution,and was further resynthesized as Li Ni_0.6Co_0.2Mn_0.2O₂ materials via roasting with Ni_0.6Co_0.2Mn_0.2（OH）₂ precursor.The electrochemical test indicated that of resynthesized Li Ni_0.6Co_0.2Mn_0.2O₂ materials have an excellent discharge capacity of 157.21 m Ah/g at 0.1 A/g,and a outstanding cyclic stability（131.15 mAh/g after 100 cycles at 1 A/g）.Specifically,the spent LiNi_1-x-yCo_xAl_yO₂（NCA）material and pyrite material（Fe S₂）is roasted to selective recycling lithium from spent NCA materials,realizing the“waste recycling waste”model and further improving the economic profit.A detailed thermodynamic calculation and a series of characterization analyses were conducted to reveal the conversion of metal elements in the roasting process,proving that the NCA materials were transformed into water-soluble Li₂SO₄ and insoluble Ni-Co metal oxides via reacting with Fe S₂ in an aerobic atmosphere.To explore the optimal experimental conditions,selective extracting experiments of lithium under different experimental parameters were conducted.Under the conditions of roasting temperature of 800 ^oC,roasting time of 360 min and raw material mass ratio（NCA:pyrite）of1:1.2,the lithium leaching efficiency could reach the peak（98.68%）,accompanied by a low leaching effect of nickel and cobalt.Finally,a regenerated Li₂CO₃ was prepared from the lithium-contained leaching solution,and was further resynthesized as Li Ni_0.6Co_0.2Mn_0.2O₂ materials via roasting with Ni_0.6Co_0.2Mn_0.2（OH）₂ precursor.The electrochemical test indicated that of resynthesized Li Ni_0.6Co_0.2Mn_0.2O₂ materials have an excellent discharge capacity of 144.90 m Ah/g at 0.1 A/g,and a outstanding cyclic stability（84.39%capacity retention rate after 100cycles at 1 A/g）.