烧结助剂Al2O3与Y2O3对固态锂离子电解质LLZO的锂离子电导率的影响

摘要

The garnet-type ceramic electrolyte Li7La3Zr2O12(LLZO) with composition of xAl2O3-Li7La3Zr2O12(x=0-0.4) and xY2O3-Li7La3Zr2O12(x=0, 0.1, 0.2, 0.3 and 0.4) were synthesized by adding Al2O3 and Y2O3 as sintering aids and using Li2CO3, La2O3 and ZrO2 as raw materials. The effects of the contents of sintering aids Al2O3 and Y2O3 on the lithium ion conductivity of solid lithium ion electrolyte LLZO were studied. The results reveal that two kinds of sintering aids both can stabilize the cubic phase of garnet structure LLZO after sintered at 1500 ℃ for 15 h. The LaAlO3 impurity phase is produced when Al2O3 is over added. The Li2ZrO3 and YO1.458 impurity phases are produced when Y2O3is over added. Among these samples,0.2Y2O3-LLZO can stabilize the cubic phase from 1100 ℃ to 1200 ℃ and do not decompose when sintering at 1150 ℃ for 27 h.The density of LLZO and the conductivity of lithium ion increase first and then decrease with increasing the content of sintering aids. The optimum additions of Al2O3 and Y2O3 are 0.2 and 0.3, respectively. The density and ionic conductivity of 0.2Al2O3-LLZO are 94% and 1.78×10-4S/cm, respectively. The density and ionic conductivity of 0.3Y2O3-Li7La3Zr2O12 are 96% and 5.23×10-4S/cm, respectively.%以 Li2CO3,La2O3和 ZrO2为原料,分别添加 Al2O3和 Y2O3作为烧结助剂,制备锂离子固态电解质xAl2O3-Li7La3Zr2O12和xY2O3-Li7La3Zr2O12(分别简称为xAl2O3-LLZO和xY2O3-LLZO.x为摩尔分数,x=0,0.1, 0.2,0.3,0.4和0.5),研究Al2O3和Y2O3的添加量对LLZO的结构与锂离子电导率的影响.结果表明,在1150 ℃烧结15 h时,Al2O3和Y2O3这2种烧结助剂都能稳定立方相石榴石结构LLZO.当Al2O3过量时,产生LaAlO3杂相,当Y2O3过量时,产生Li2ZrO3和YO1.458杂相.0.2Y2O3-LLZO在1100~1200℃范围内能形成稳定的立方相石榴石结构LLZO,并且在1150 ℃烧结27 h不发生分解反应;LLZO的致密度和锂离子电导率都随烧结助剂含量增加而先增加后减小,Al2O3和Y2O3的最佳添加量x分别为0.2和0.3,所得0.2Al2O3-LLZO的致密度与离子电导率分别为94%和1.78×10-4S/cm,0.3Y2O3-Li7La3Zr2O12的致密度与离子电导率分别为96%和5.23×10-4S/cm.