空位缺陷
锂(药物)
兴奋剂
化学计量学
电解质
材料科学
固溶体
晶体缺陷
离子
密度泛函理论
离子键合
化学物理
化学
结晶学
计算化学
物理化学
电极
内分泌学
医学
光电子学
有机化学
冶金
作者
Alexander G. Squires,David O. Scanlon,Benjamin Morgan
标识
DOI:10.1021/acs.chemmater.9b04319
摘要
The Li-stuffed garnets LixM2M3′O12 are promising Li-ion solid electrolytes with potential use in solid-state batteries. One strategy for optimizing ionic conductivities in these materials is to tune lithium stoichiometries through aliovalent doping, which is often assumed to produce proportionate numbers of charge-compensating Li vacancies. The native defect chemistry of the Li-stuffed garnets and their response to doping, however, are not well understood, and it is unknown to what degree a simple vacancy-compensation model is valid. Here, we report hybrid density functional theory calculations of a broad range of native defects in the prototypical Li garnet Li7La3Zr2O12. We calculate equilibrium defect concentrations as a function of synthesis conditions and model the response of these defect populations to extrinsic doping. We predict a rich defect chemistry that includes Li and O vacancies and interstitials, and significant numbers of cation-antisite defects. Under reducing conditions, O vacancies act as color centers by trapping electrons. We find that supervalent (donor) doping does not produce charge compensating Li vacancies under all synthesis conditions; under Li-rich/Zr-poor conditions the dominant compensating defects are LiZr antisites, and Li stoichiometries strongly deviate from those predicted by simple “vacancy compensation” models.
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