AlPO_4包覆对LiVOPO_4电化学性能的影响

Effect of AlPO_4 Coating on the Electrochemical Properties of LiVOPO_4 Cathode Material

以LiVOPO4、Al(NO3)3.9H2O、H3PO4为原料,采用溶胶-凝胶法制备了AlPO4包覆的LiVOPO4粉末(AlPO4包覆LiVOPO4)。采用热重与差热分析、X射线衍射分析、扫描电镜分析以及电化学测试等手段对AlPO4包覆LiVOPO4的微观结构、表面形貌和电化学性能进行了研究。结果表明,AlPO4以无定形态包覆于LiVOPO4颗粒表面形成AlPO4包覆LiVOPO4粉末。由于在LiVOPO4颗粒表面包覆了一层无定形的AlPO4后,阻止了电极与电解质溶液之间的副反应,降低了电化学阻抗,因此,与未包覆的LiVOPO4粉末相比,AlPO4包覆LiVOPO4具有更高的可逆容量、更稳定的循环性能和更好的倍率性能。

AlPO4-coated LiVOPO4 were prepared by sol-gel method using LiVOPO4, AI（NOa ）3·9H2O and Ha PO4 as raw materials. The microstructure, surface morphology and electrochemical properties were characterized by various electrochemical methods in combination with thermogravimertric（TG） analysis and differential thermal analysis（DTA）, X-ray diffraction（XRD） and scanning electron microscope（SEM）. It is found that the amorphous AlPO4 layer coats on the surface of LiVOPO4. The AlPO4-coated LiVOPO4 cathode material has increased reversible capacity, stabilized cycling performance and improved rate performance, which are attributed to the minimization harmful side reactions within the batteries by placing a protective barrier layer between the oxidizing cathode material and liquid electrolyte and the decrease of electrochemical impedance.