Combined Experimental and Computational Study of Ce-Doped La 3 Zr 2 Li 7 O 12 Garnet Solid-State Electrolyte
Combined Experimental and Computational Study of Ce-Doped La 3 Zr 2 Li 7 O 12 Garnet Solid-State Electrolyte
复制标题
Ce掺杂La 3 Zr 2 Li 7 O 12 石榴石固态电解质的实验与计算联合研究
DOI：
10.1021/acs.chemmater.9b03526
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发表时间：
2019
影响因子：
8.6
通讯作者：
Dong B
中科院分区：
文献类型：
--
作者：
Dong B
含锂石榴石材料作为锂离子电池潜在的固体电解液引起了人们的极大兴趣。在这样的Ln3M2LixO12(Ln=稀土，碱土；M=Zr，Hf，Sn，Nb，Ta，Sb，Bi，Te)中，Li含量x略低于最大值7.0时，Li离子的导电性最好。X=7.0体系的电导率下降与Li有序化(晶胞从立方变为四方)有关，以防止Li-Li相互作用太短。在这项工作中，我们报道了Ce4+掺杂La3Zr2Li7O12的实验和模拟相结合的研究。我们首次发现Ce4+可以掺杂到该材料中的Zr4+位上。由于晶胞尺寸的增大降低了Li-Li相互作用应变，这种掺杂策略降低了四方相变的温度和四方相变的温度。加上这些变化，电导率显示出显著(1.5个数量级)的改善。此外，Ce掺杂还降低了Li7La3Z1.75Ce0.25O12与Li金属接触时的界面电阻(388Ωcm2)，为这一掺杂策略提供了额外的潜在好处。证明了Li//石榴石//Li对称电池在190h以上的长期循环稳定性。
Li-containing garnet materials have been attracting considerable interest as potential solid-state electrolytes for Li ion batteries. In such Ln3M2LixO12(Ln = lanthanide, alkaline earth; M = Zr, Hf, Sn, Nb, Ta, Sb, Bi, Te), the best Li ion conductivity is observed for Li contents,x, just below the maximum 7.0. The decrease in conductivity forx= 7.0 systems is related to Li ordering (cell changes from cubic to tetragonal) to prevent too short Li–Li interactions. In this work, we report a combined experimental and modeling study of Ce4+doping in La3Zr2Li7O12. We show for the first time that Ce4+can be doped onto the Zr4+site in this material. This doping strategy results in a reduction in the tetragonal distortion as well as a lowering of the temperature of the tetragonal–cubic phase transition, attributed to the increase in cell size reducing Li–Li interaction strain. Coupled with these changes, the conductivity shows a significant (1.5 orders of magnitude) improvement. Furthermore, the Ce doping also reduces the interfacial resistance (388 Ω cm2for Li7La3Z1.75Ce0.25O12) in contact with Li metal, giving additional potential benefits to this doping strategy. The long-term cycling stability of a Li//garnet//Li symmetric cell over 190 h has been demonstrated.