| Ultrafine powder Co3O4 was prepared by wet chemistry method fromspent lithium ion batteries. Influence of the process parameters on theproperties of Co3O4 powder was studied. The specific area and infraredspectrum of Co3O4 powders were measured. Its morphology was observed.The results show that the prepared powders have high specific surfacearea, which is about 100m2 ·g-1;the particle average diameters distributefrom 10nm to 20nm;the particles' shape presents sphere. Compared to themarket Co3O4 , the infrared characteristic peaks of ultrafine Co3O4 aresomewhat red–shifted. This shows a kind of character of nano powders. The mechanism of Pechini process for LiCoO2 was investigated.The optimal pH for the Pechini process was studied. Two key steps,complexation and esterification, were explored with infrared spectra. Theresults show that in the solution of pH=5, citric acid exists mostly in theform of HCit 2-. During the process of complexation, complex compoundis generated by Co2+ and HCit2- . While Li+ was homogenously dispersedin the citric acid solution. During the process of fat polymerization,different complexed molecules are polymerized together by ethylenealcohol. After dehydration, the gel with space structure is formed. LiCoO2 powders were prepared by Pechini method with cobaltnitrate and lithium hydroxide as raw materials, with citric acid aschelating agent, with ethylene alcohol as cross-linking agent. Its optimaltechnological conditions were studied. The xerogel precursor wasthermally analyzed by DSC-TG. The result shows that during combustion;the xerogel precursor has three obvious mass losses. After 580℃ ,thecurve of TG tends to smooth. The crystal phases of LiCoO2 wereinvestigated by XRD. The result shows that the lattice parameters ofLiCoO2 prepared at 680℃ are a=2.8153A and c=14.0404A (c/a=4.98706).The specific surface area of LiCoO2 powders was tested by BETtechnique. The result shows that the specific surface area of LiCoO2powders by Pechini method can reach 14.44m 2 ·g-1;the mean diameter ofparticles is 0.090μ m.LiCoO2 powders were prepared by PVA-assisted Sol-Gel methodwith cobalt nitrate and lithium hydroxide as raw materials, with polyvinylalcohol as chelating agent. Its optimal technological conditions werestudied. The xerogel precursor was thermally analyzed by DSC-TG. Theresult shows that layer-structured LiCoO 2 crystals are obtained afterheated at 580℃ for 1h. The crystal phases of LiCoO 2 were investigatedby XRD. The result shows that the lattice parameters of LiCoO 2 preparedat 580℃ are a=2.81519? and c=14.04535? (c/a= 4.98913). The specificsurface area of LiCoO 2 powders was tested by BET technique. The resultshows that the specific surface area of LiCoO 2 powders by PVA-assistedSol-Gel method can reach 6.913m 2 ·g -1;the mean diameter of particles is0.211μ m.
|
PDF Full Text Request