以固相法制备出了磷酸亚铁锂-磷酸钒锂复合正极材料。采用X-射线衍射仪(XRD)、电子扫面电镜(SEM)、激光粒度分析仪、碳硫分析仪以及X-光电子能谱仪等对制备出的复合材料进行表征,发现该材料以磷酸亚铁锂和磷酸钒锂的晶形结构为主,其中有少量的杂质成分;该材料颗粒粒度较细、粒度分布窄且均匀,颗粒表面光滑、碳包裹状况良好,同其它方法制备的复合材料比较在碳含量差不多的情况下具有较优的导电率。对材料进行了电化学性能表征认为该材料的电化学性能比较优异,0.1 C放电容量达到190 mA h g 1以上,10 C可以达到120 mA h g 1,20 C放电容量仍有85 mA h g 1且循环稳定性均较好;1 C进行1000次循环之后仍然保持120 mA h g 1的容量,具有较高的实用价值。
In order to improve the lower practical capacity and bad cyclability of crystalline V2O5（c-V2O5）,the vanadium oxide（V2O5） and polypyrrole（PPy） hybrid with hollow-spherical（HS） structure was studied.HS nanocomposite comprised of conductive polypyrrole and vanadium pentoxide（PPy/V2O5） was synthesized by polymerization of pyrrole monomer（Py） in the hollow-microspherical V2O5 host.This novel hybrid was characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM） and tested as the cathode material for lithium-ion batteries（LIB） by galvanostatic cell cycling and electrochemical impedance spectroscopy（EIS）.The hollow-spherical polypyrrole/vanadium oxide（HS-PPy/V2O5） composites,in which PPy molecules are intercalated between the layers of V2O5,exhibit slight reduced capacity and substantially improve cyclability and electrochemical activity compared with the pure HS-V2O5.
LiFePO4-Li3V2（PO4）3 composites were synthesized by solid-hydrothermal method and by ball milling,respectively.The electrochemical performance of the solid-hydrothermally obtained materials（C-LFVP） was significantly improved compared with LiFePO4（LFP） and Li3V2（PO4）3（LVP）,and it was also much better than that of the ball-milled LiFePO4-Li3V2（PO4）3（P-LFVP）.C-LFVP and P-LFVP both had four REDOX peaks（voltage plateaus）,which coincided with that of LFP and LVP.Some new trace substances were found in C-LFVP which had more perfect morphology,this was responsible for the better electrochemical performance of C-LFVP than P-LFVP.
Crystalline Cu-doped V2O5 particles were prepared by the liquid precipitation method.The crystal structure,morphology and electrochemical performance of the Cu0.1V2O5 particles were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and galvanostatic cycling.XRD results indicate that Cu-doped V2O5 exhibited the same orthorhombic structure as that of un-doped V2O5.The results of galvanostatic cycling for samples show that Cu-doped V2O5 has a better electrochemical behavior.The active materials maintain the specific capacity of 185 mAhg-1 at C/5 rate over the voltage range of 2-4V after 20 cycles.
