Ba、Ga共掺杂对石榴石型固态电解质Li7La3Zr2O12显微组织及电导率的影响  

The Role of Ba and Ga Co-doping in Microstructure and Electrical Conductivity of a Garnet-type Solid State Electrolyte Li7La3Zr2O12

作　　者：董大彰 赵梦媛 解昊 边凌峰 杨星 孟彬[1] DONG Dazhang;ZHAO Mengyuan;XIE Hao;BIAN Lingfeng;YANG Xing;MENG Bin(Faculty of Material Science and Engineering,Kunming University of Science and Technology,Kunming 650093,China)

机构地区：[1]昆明理工大学材料科学与工程学院

出　　处：《材料导报》2020年第4期1-6,共6页Materials Reports

基　　金：国家自然科学基金(51462018);云南省大学生创新创业训练计划项目(201710674203)~~

摘　　要：采用固相法合成了Ba与Ga共掺杂的Li7La3Zr2O12(LLZO)石榴石型固态电解质粉末,再结合常压烧结制备了Ba、Ga共掺杂LLZO样品。采用X射线衍射、扫描电镜、能谱分析和交流阻抗法对样品的物相结构、微观形貌、成分分布及电导率进行了表征。结果表明,在烧结温度1100℃下得到了立方相的LLZO固态电解质。当Ga的含量在LLZO化学式中为0.15,Ba掺杂量从0增加至0.15(Ga 0.15 Bax-Li 6.55+x La3-xZr2O 12,x=0~0.15)时,LLZO样品的平均晶粒尺寸从14μm下降到4μm,30℃时晶界电导率由1.54×10^-5 S·cm^-1提升到2.22×10^-4 S·cm^-1。Ba作为一种烧结剂,改善了材料的烧结性能,降低了材料的平均晶粒尺寸,使晶粒与晶粒连接得更紧密。Li 6.7 Ga0.15La2.85Ba0.15Zr2O12样品在30℃下的总电导率为2.11×10^-4 S·cm^-1,远高于单独掺杂Ga时Li6.55Ga0.15La3Zr2O12样品的总电导率(σ=1.40×10^-5 S·cm^-1),由此可见,Ba、Ga共掺杂极大地提高了LLZO的锂离子电导率。Ba and Ga co-doped Li7La3Zr2O12(LLZO),a garnet-type lithium ion solid-state electrolyte was prepared by a two-step approach:synthesis of LLZO powers by conventional solid-state reaction and sintering in the atmosphere.Then,the crystal structure,microstructure,composition distribution and ionic conductivity were characterized by X-ray diffraction,scanning electron microscope,energy dispersive spectrometer and electrochemical impedance spectroscopy.It was found that the cubic phase LLZO could be obtained under the sintering temperature of 1100℃.When the content of Ga in LLZO was 0.15,and the doping amount of Ba altered from 0 to 0.15(Ga 0.15 Bax-Li 6.55+xLa3-x Zr2O12,x=0-0.15),the LLZO sample exhibited a drop in the average grain size from 14μm to 4μm and a rise in the grain boundary conductivity(30℃)from 1.54×10^-5 S·cm^-1 to 2.22×10^-4 S·cm^-1.As a kind of sintering agent,the Ba played an critical role in improving the sintering performance,reducing the average grain size,and promoting the bonding between grains in the LLZO samples.Notably,the Li6.7Ga0.15 La2.85Ba0.15Zr2O12 sample presented a total conductivityσof 2.11×10^-4 S·cm^-1 at 30℃,which was much higher than that of Li 6.55 Ga 0.15 La 3Zr 2O 12 sample with single doping of Ga(σ=1.40×10^-5 S·cm^-1 at 30℃),demonstrating the significant contribution of Ba and Ga co-doping to the Li-ion electrical conductivity of LLZO.

关 键 词：Li7La3Zr2O12 石榴石型固态电解质 元素掺杂 电导率 

分 类 号：TB34[一般工业技术—材料科学与工程]