| As Li-ion batteries became commercialized,they have been favored by electronic information and new electric vehicle industry.With the increasing consumption of Li-ion batteries,the effective disposal of spent Li-ion batteries is a problem that can not be ignored.Compared with rare earth magnetostrictive materials,cobalt ferrite materials based on iron ferrite are cheaper,easy to get,low cost,good mechanical properties,high corrosion resistance and excellent magnetostrictive properties.Therefore,the reprocessing of spent Li-ion batteries and the preparation of cobalt ferrite magnetostrictive materials will not only solve the problem of resource shortage,but also help the sustainable development of the economy.In this paper,the preparation of cobalt ferrite from spent Li-ion batteries and the influence of rare earth elements doping on the structure,morphology,magnetic properties and magnetostriction of cobalt ferrite are mainly discussed.The specific research contents and conclusions are as follow:?1?A series of rare earth elements Ce,Pr and Nd doped cobalt ferrite were prepared by sol-gel auto-combustion method.The regularity of magnetic and magnetostrictive properties of the samples were analyzed and discussed.?2?On the basis of single rare earth doped,the effects of two kinds of rare earth mixed doped on the properties of cobalt ferrite were further studied by sol-gel auto-combustion method.?3?On the basis of double rare earth doped,the effects of different content of Cu substituted Co on the properties of rare earth cobalt ferrite CuxCo1-xCe0.05Nd0.05Fe1.9O4 were investigated.?4?The effects of different pH,hydrothermal time and temperature on the micromorphology and magnetostrictive properties of cobalt ferrite in microwave hydrothermal method were discussed.The samples were characterized by X-ray diffraction?XRD?,field emission scanning electron microscope?FE-SEM?and high resolution transmission electron microscope?HR-TEM?.The magnetic and magnetostriction energies of the samples were measured by vibrating sample magnetometer?VSM?,and a magnetostrictive coefficient measuring system.The research shows:?1?RE3+subtitution for Fe3+in CoFe2O4 samples can change the ferromagnetic structure of cobalt ferrite,improve the magnetostriction characteristics of samples at low magnetic field intensity,but the impurity phase of REFeO3 will be generated due to the solubility limit.The magnetostrictive properties of CoNd0.025Fe1.975O4 in the rare earth doped cobalt ferrite are better,?max=-152.5×10-6.The strain derivative of CoNd0.05Fe1.95O4 is better,?d?/dH?max=-1.49×10-9 m/A.?2?The maximum magnetostriction coefficient of the double rare earth doped cobalt ferrite CoRE10.05RE20.05Fe1.9O4 prepared is Ce and Nd doped sample?max=-163.1×10-6,and the maximum strain derivative is Ce and Pr doped sample?d?/dH?max=-1.77×10-9 m/A.The magnetostriction parameters(?maxax and?d?/dH?max)obtained in the samples doped with Ce elements in the same content of double rare earth doped have been improved compared with the single rare earth dopants,and the corresponding magnetic field strength remains basically unchanged.?3?In the CuxCo1-xCe0.05Nd0.05Fe1.9O4 system,x=0.15 presents larger?max=-167.6×10-6 and?d?/dH?max=-1.82×10-9 m/A,This indicated that adding copper into double rare earth doped cobalt ferrite samples could reduce the magnetic field strength,and further improve the magnetostrictive properties of rare earth cobalt ferrite materials.?4?The samples prepared by microwave hydrothermal method were homogeneous,the average grain sizes between 1020 nm,magnetostrictions good,and there were large strain derivatives in low magnetic field.such as the reaction time was 1.5 h,pH=11 at 160oC,?d?/dH?max=-4.35×10-9 m/A;the reaction time is 2.0 h,pH=11,at 200oC?d?/dH?max=-4.18×10-9 m/A.In this paper,we have provided an effective way to study the recycling of spent Li-ion batteries,which is of great significance to the development of the environment-friendly economy. |
PDF Full Text Request