Birkner Nancy, Li Changlong, Estes Shanna L, Brinkman Kyle S
Department of Materials Science and Engineering, Clemson University, Clemson, SC 29634, USA.
Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, SC 29625, USA.
ChemSusChem. 2021 Jun 21;14(12):2621-2630. doi: 10.1002/cssc.202100526. Epub 2021 May 13.
One of the most promising electrolytes for all-solid-state lithium batteries is Li La Zr O . Previously, their thermodynamic stability, Li-ion conductivity, and structural features induced by Ga-doping have not been empirically determined or correlated. Here, their interplay was examined for Li Ga La Zr O with target xGa=0, 0.25, 0.50, 0.75, and 1.00 atoms per formula unit (apfu). Formation enthalpies, obtained with calorimetry and found to be exothermic at all compositions, linearly decreased in stability with increased xGa. At dilute xGa substitution, the formation enthalpy curve shifted stepwise endothermically, and the conductivity increased to a maximum, coinciding with 0.529 Ga apfu. This correlated with percolation threshold analysis (0.558 Ga apfu). Further substitution (0.787 Ga apfu) produced a large decrease in the stability and conductivity due to a large increase in point defects and blocked Li-migration pathways. At xGa=1.140 apfu, a small exothermic shift was related to defect cluster organization extending the Li hopping distance and decreased Li-ion conductivity.
全固态锂电池最有前景的电解质之一是LiLaZrO。此前，其热力学稳定性、锂离子电导率以及由镓掺杂引起的结构特征尚未通过实验确定或关联。在此，研究了LiGaLaZrO（目标xGa = 0、0.25、0.50、0.75和1.00原子/化学式单元（apfu））中它们之间的相互作用。通过量热法获得的生成焓在所有组成下均为放热，且随着xGa的增加稳定性呈线性下降。在稀xGa取代时，生成焓曲线逐步向吸热方向移动，电导率增加至最大值，与0.529 Ga apfu一致。这与逾渗阈值分析（0.558 Ga apfu）相关。进一步取代（0.787 Ga apfu）由于点缺陷大幅增加和锂迁移路径受阻，导致稳定性和电导率大幅下降。在xGa = 1.140 apfu时，一个小的放热转变与缺陷簇组织有关，该组织延长了锂的跳跃距离并降低了锂离子电导率。
