Electrochemical performance of carbon-coated Na3.35Mn1.15Ti0.80V0.05(PO4)3 cathode materials
Sodium super ionic conductor(NASICON)type Na3MnTi(PO4)3(NMTP)is a promising cathode material due to its high voltage and low cost.However,its low electronic conductivity and low coulombic efficiency limit its commercial application.In order to solve these problems,carbon-free and citric acid coated Na3.35Mn1.15Ti0.80V0.05(PO4)3(NMTVP)samples were prepared by spray drying process,respectively.The structure and morphology of the samples were characterized using X-ray diffraction(XRD),thermogravimetric analysis(TGA)and scanning electron microscopy(SEM).The results show that citric acid can form a uniform carbon coating on the surface of NMTVP,which also acting as a dispersant to ensure the even distribution of transition metals,reducing cation mixing and inhibiting the formation of impurity phase,such as Mn(PO3)2 and NaTi2(PO4)3.Carbon coating effectively isolates the cathode from the electrolyte,suppresses the interface side reaction and manganese dissolution,and thus reduces the interfacial impedance.The carbon coated NMTVP@C exhibits excellent electrochemical performance,with an initial discharge specific capacity of 96.2 mA·h·g-1 at 0.1 C,and significantly improves rate capability and cycling performance.
万方数据
