无机材料学报 ›› 2015, Vol. 30 ›› Issue (9): 995-1001.DOI: 10.15541/jim20150163

• • 上一篇    下一篇

高电导率F掺杂Li7La3Zr2O12石榴石结构固体电解质

刘 才, 温兆银, 芮 琨   

  1. (中国科学院 上海硅酸盐研究所, 中国科学院能量转换材料重点实验室, 上海200050)
  • 收稿日期:2015-04-07 出版日期:2015-06-10 网络出版日期:2015-08-19

High Ion Conductivity in Garnet-type F-doped Li7La3Zr2O12

LIU Cai, WEN Zhao-Yin, RUI Kun   

  1. (CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China)
  • Received:2015-04-07 Published:2015-06-10 Online:2015-08-19
  • Supported by:
    Foundation item: National Natural Science Foundation of China(51373195, 51272267, 51432010);Key Fundamental Research Project from Science and Technology Commission of Shanghai Municipality(14JC1493000)

摘要:

通过传统固相反应法合成一种新型的F掺杂Li7La3Zr2O12 (LLZO)石榴石结构固体电解质。添加适量LiF和CaF2等氟化物经过两步煅烧在室温下获得纯立方相的LLZO陶瓷粉体, 验证氟离子掺杂具有稳定石榴石结构立方相和增强陶瓷烧结活性的作用。制备的1wt% LiF-LLZO电解质总电导率达5×10-4 S/cm, 接近立方相LLZO的体电导率, 电导活化能仅为0.26 eV, 低于其他阳离子掺杂的LLZO。(321)、(400)、(642)和(800)晶面衍射峰由于晶粒的生长取向而显著增强, 陶瓷内部晶界消失, 形成由闭气孔构成的独特显微结构, 导致该新型电解质的晶界阻抗的消失和总电导率的提升。

关键词: 固体电解质, 石榴石结构, 氟离子掺杂, 显微结构

Abstract:

A novel garnet-type solid electrolyte, F-doped Li7La3Zr2O12 (LLZO), was prepared via conventional solid-state reaction. Certain fluoride compounds were known to form the pure cubic garnet structure after continuous calcination at 900℃ and 1125℃, seperately. Fluorine ions doped in LLZO contributed to the stabilization of high ion conductivity garnet phase as well as the enhancement of sintering activity. The effects of fluorine ions were studied using the dopants LiF and CaF2. The 1.0wt% LiF-LLZO samples exhibited a total conductivity of 5×10-4 S/cm close to the bulk conductivity value of un-doped LLZO, while its activation energy was 0.26 eV, lower than that of other cation-doped LLZO samples. The strong intensity of the peaks indexed to (321), (400), (642), and (800) in XRD patterns indicated the growth of ceramic grains of F-doped LLZO in certain favorable crystallographic orientations during sintering process. In addition, a unique microstructure was revealed in the novel garnet-type oxide pellets, showing the grain boundary almost removed and closed pores formed, which resulted in the negligible grain boundary and the high total ion conductivity.

Key words: solid electrolyte, garnet-type, fluorine ion doping, microstructure