Research On Recycling Of Ternary Cathode Materials By Potential Regulation Method

As a strategic emerging industry,the new energy vehicle industry has developed rapidly in recent years.As the key component of electric vehicles,the power battery,gradually reaches its service life,the amount of its scrapping is increasing.Especially for ternary lithium batteries,due to their serious environmental hazards and excellent resource attributes,realizing their green and efficient resource utilization not only has important economic value,but also has important significance for alleviating the shortage of energy metals and protecting the ecological environment.Taking advantage of the electrical conductivity of lithium battery materials and the difference in electrochemical properties between components,a new method for electrolytic recovery of ternary cathode materials based on potential polarity regulation is proposed.The main research contents are as follows:（1）Priority and selective extraction of lithium by anode slurry electrolysis:For anodic slurry electrolysis,polarization curve analysis and comparative experimental study were used to analyze the reaction mechanism of anode electrode.In the process of anode slurry electrolysis,under the combined action of anode direct oxidation and HCl O/Cl O^-indirect oxidation,the ternary cathode material is oxidized to nickel-cobalt-manganese oxide,and lithium is extracted from the material.Indirect oxidation under the action of HCl O is the main reaction in the electrolysis process.Taking the leaching rate of lithium and anode current efficiency as indicators,the influence of various experimental factors on the electrolysis process was investigated,and the optimal experimental conditions for anode slurry electrolysis were determined,and the selective and preferential extraction of Li 96.68%、Ni 1.4%,Co and Mn are basically not leached.（2）Electrolytic leaching of nickel-cobalt-manganese cathode slurry:For cathodic slurry electrolysis,polarization curve analysis and comparative experimental study were used to analyze the cathodic electrode reaction mechanism.During the electrolysis of the cathode slurry,under the combined action of acid dissolution,cathode direct reduction,and Fe³⁺indirect reduction,nickel,cobalt,and manganese oxides are leached at the cathode,and the valuable metals Ni,Co,and Mn enter the catholyte,and the indirect reduction under the action of Fe³⁺is The main reaction of the electrolysis process.Taking the leaching rate and cathode current efficiency of nickel-cobalt-manganese oxides as indicators,the influence of various experimental factors on the electrolysis process was investigated,and the optimal experimental conditions for cathode slurry electrolysis were determined.The final leaching rate of Ni,Co and Mn>96%.（3）Cyclic enrichment and product preparation of lithium-nickel-cobalt electrolyte:For the lithium anolyte and nickel-cobalt catholyte obtained by slurry electrolysis,valuable metals are recovered from the solution through cyclic enrichment,impurity removal,precipitation,etc.The lithium anolyte was electrolyzed for 8 cycles to obtain a solution containing Li 18.28 g·L^-1.The sodium carbonate precipitation method was used to remove 92.35%of Ni in the solution,and then Li₂CO₃ was obtained by saturated sodium carbonate precipitation.Nickel-cobalt catholyte was electrolyzed for 3 cycles to obtain a solution containing Ni 25.77 g·L^-1 and Co 10.57 g·L^-1,and 98.2%Mn was removed by potassium permanganate precipitation method,and then separated by sodium hypochlorite and sodium carbonate.Step precipitation to obtain Co（OH）₃,Ni CO₃.To sum up,the selective preferential extraction of lithium by anode slurry electrolysis,the electrolytic leaching of nickel-cobalt-manganese cathode slurry and the subsequent treatment of the electrolyte have realized the step-by-step extraction and recovery of Li,Ni,Co,and Mn in the ternary cathode material.