1. Gallium‐Doping Effects on Structure, Lithium‐Conduction, and Thermochemical Stability of Li 7‐3 x Ga x La 3 Zr 2 O 12 Garnet‐Type Electrolytes
- Author
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Shanna L. Estes, Kyle S. Brinkman, Changlong Li, and Nancy Birkner
- Subjects
Materials science ,General Chemical Engineering ,Enthalpy ,chemistry.chemical_element ,Thermodynamics ,Percolation threshold ,02 engineering and technology ,Calorimetry ,Conductivity ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Crystallographic defect ,0104 chemical sciences ,General Energy ,chemistry ,Formula unit ,Environmental Chemistry ,General Materials Science ,Lithium ,Chemical stability ,0210 nano-technology - Abstract
One of the most promising electrolytes for all-solid-state lithium batteries is Li7 La3 Zr2 O12 . 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 Li7-3x Gax La3 Zr2 O12 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.
- Published
- 2021
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