Y^(3+)掺杂Li_(4)Ti_(5)O_(12)负极材料的电荷输运特性及电化学性能研究

Transport characteristics and electrochemical properties of Y^(3+)doped Li_(4)Ti_(5)O_(12)as anode material

以Li_(2)CO_(3)与锐钛矿型TiO_(2)为原料,六水合硝酸钇(Y(NO_(3))_(3)·6H_(2)O)为钇源,采用球磨辅助固相法合成了Li_(4)Ti_(5-x)Y_(x)O_(12)(x=0,0.05,0.10,0.15,0.20)负极材料。通过X射线衍射分析(XRD)、扫描电镜(SEM)、能谱仪(EDS)与X射线光电子能谱(XPS)分别对材料的物相与形貌进行表征分析,并利用电化学工作站对材料的电化学性能与电荷输运特性进行测试。结果表明,Y^(3+)掺杂没有影响尖晶石型Li_(4)Ti_(5)O_(12)(LTO)材料的尖晶石结构,x=0.15时,Li_(4)Ti_(4.85)Y_(0.15)O_(12)样品的离子与电子电导率分别为2.68×10^(-7)S·cm^(-1)和1.49×10^(-9)S·cm^(-1),比本征材料提升了1个数量级,表现出良好的电荷输运特性。电化学测试表明,Li_(4)Ti_(4.85)Y_(0.15)O_(12)样品在0.1 C倍率首次放电比容量可达171 mAh·g^(-1),且在10 C与20 C高倍率下仍然拥有102 mAh·g^(-1)和79 mAh·g^(-1)的较高比容量,循环200周次后容量保持率分别为92.6%和89.1%,表现出良好的倍率特性。

Li_(4)Ti_(5-x)Y_(x)O_(12)(x=0,0.05,0.10,0.15,0.20)anode materials were synthesized by ball milling assisted solid-state method used Li_(2)CO_(3) and anatase TiO_(2) as raw materials and yttrium nitrate(Y(NO_(3))_(3)·6H_(2)O)as yttrium source.The phase and morphology of the materials were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and X-ray photoelectron spectroscopy(XPS),respectively.The electrochemical performance and transport characteristics of the materials were tested and analyzed by an electrochemical workstation.The results show that there is no effect of Y^(3+)doping on the spinel structure of LTO material.When x=0.15,the ion and electronic conductivities of the Li_(4)Ti_(4.85)Y_(0.15)O_(12) sample are 2.68×10^(-7)S·cm^(-1)and 1.49×10^(-9)S·cm^(-1),respectively,which are an order of magnitude higher than that of the intrinsic LTO,and present good transport characteristics.Electrochemical tests show that a first discharge capacity of Li_(4)Ti_(4.85)Y_(0.15)O_(12)sample can reach 171 mAh·g^(-1)at 0.1 C rate.The sample still has a higher specific capacity of 102 mAh·g^(-1)and 79 mAh·g^(-1)at a high rate of 10 C and 20 C,respectively.After 200 cycles,the capacity retention rates are 92.6%and 89.1%respectively,showing good magnification characteristics.