Phase transition in lithium garnet oxide ionic conductors Li7La3Zr2O12: The role of Ta substitution and H2O/CO2 exposure
Phase transition in lithium garnet oxide ionic conductors Li7La3Zr2O12: The role of Ta substitution and H2O/CO2 exposure
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DOI：
10.1016/j.jpowsour.2014.11.062
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发表时间：
2015-02
影响因子：
9.2
通讯作者：
Yuxing Wang;Wei Lai
中科院分区：
文献类型：
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作者：
Yuxing Wang;Wei Lai
高锂含量的锂石榴石氧化物是一种很有前途的锂电池固体电解质材料。作为锂含量最高的锂石榴石氧化物，Li7La3Zr2O12已被报道以四方相或立方相结晶，但对这两种相形成的确切条件没有共识，这可能是由于无意的Al污染和空气暴露。在这项工作中，Ta的替代和H2O/CO2暴露的影响进行了研究，铝污染的条件下，最小的空气暴露。结果表明：1）Ta取代诱导的相变是通过两相机制发生的，至少需要0.6 mol Ta取代Zr才能稳定立方相; 2）H2O和CO2分别通过质子交换和Li萃取诱导Li7La3Zr2O12的四方-立方相变，这对Li7La3Zr2O12的输运性质有很大影响。
High Li-content lithium garnet oxides are promising solid electrolyte materials for lithium batteries. Being the highest Li-content lithium garnet oxides, Li7La3Zr2O12has been reported to crystallize in either the tetragonal or cubic phase with no consensus on the exact conditions under which these two phases are formed, which may be due to unintentional Al contamination and air exposure. In this work, the effects of Ta substitution and H2O/CO2exposure have been studied under Al-contamination free conditions with minimal air exposure. We showed that 1) the Ta-substitution induced phase transition occurred through a two-phase mechanism and a minimum 0.6 mol of Ta substitution to Zr is needed to stabilize the cubic phase; 2) H2O and CO2can individually induce the tetragonal-cubic phase transition in Li7La3Zr2O12through proton exchange and Li extraction, respectively, which can have great influence on the transport properties of Li7La3Zr2O12.