Li3BO3-Li6.5La3Zr1.5Ta0.5O12复合固态电解质制备及锂离子导电性能研究

Synthesize and lithium ionic conductivity of the Li3BO3-Li6.5La3Zr1.5Ta0.5O12 composite solid electrolyte

为在较低烧结温度下制备具有高锂离子电导率的Li6.5La3Zr1.5Ta0.5O12电解质,采用固相法,将低熔点的硼酸锂(Li3BO3)固态电解质按照一定比例与Li6.5La3Zr1.5Ta0.5O12电解质复合,制备了10组含有不同比例Li3BO3添加量的Li3BO3-Li6.5La3Zr1.5Ta0.5O12复合固态电解质(Li3BO3与Li6.5La3Zr1.5Ta0.5O12物质的量比值为0~0.9),相应烧结温度降低至800℃。同时为明确Li3BO3对复合电解质致密化烧结的影响规律及作用机制,对10组复合电解质的组成、结构形貌及离子电导率性能进行横向比较。发现其锂离子电导率随Li3BO3添加量的增加出现先升高后降低的趋势,其中Li3BO3与电解质物质的量比值为0.7的样品室温锂离子电导率高于其他9组,约为4.5×10^-5 S/cm,而未添加Li3BO3样品锂离子电导率仅为5.5×10^-6 S/cm。通过扫描电子显微镜(scanning electron microscope,SEM)观察发现,Li3BO3可促使Li6.5La3Zr1.5Ta0.5O12晶粒长大及致密化,因此通过与Li3BO3复合可提高Li6.5La3Zr1.5Ta0.5O12电解质的性能。

For synthesizing Li6.5La3Zr1.5Ta0.5O12solid electrolyte with high lithium-ionic conductivity at a relatively low temperature, another kind of solid electrolyte with lower melting point, Li3BO3, was added, and the molar ratio of Li3BO3 to Li6.5La3Zr1.5Ta0.5O12 changed from 0 to 0.9. As a result, the sintering temperature decreased to 800 ℃. Meanwhile, the influence rules of Li3BO3 on the composition, structure and ionic conductivity of the composite electrolytes were detected and analyzed. The lithium ion conductivity of the electrolytes went up firstly and then decreased as the amount of Li3BO3 increased. And the sample with the molar ratio of 0.7 Li3BO3 got the highest ionic conductivity as high as 4.5×10^-5 S/cm at room temperature, while the sample without Li3BO3 had only 5.5×10^-6 S/cm. Moreover, according to the scanning electron microscope(SEM) results, the addition of Li3BO3 could promote the grain growth and densification of Li6.5La3Zr1.5Ta0.5O12, as well as the total properties of the composite electrolyte.