Abstract
ABSTRACT: The oxide known as LLZO, with nominal composition
Li7La3Zr2O12, is a promising solid electrolyte for Li-based batteries due
to its high Li-ion conductivity and chemical stability with respect to
lithium. Solid electrolytes may also enable the use of metallic Li anodes
by serving as a physical barrier that suppresses dendrite initiation and
propagation during cycling. Prior linear elasticity models of the Li
electrode/solid electrolyte interface suggest that the stability of this
interface is highly dependent on the elastic properties of the solid
separator. For example, dendritic suppression is predicted to be
enhanced as the electrolyte’s shear modulus increases. In the present
study a combination of first-principles calculations, acoustic impulse
excitation measurements, and nanoindentation experiments are used to determine the elastic constants and moduli for highconductivity
LLZO compositions based on Al and Ta doping. The calculated and measured isotropic shear moduli are in good
agreement and fall within the range of 56−61 GPa. These values are an order of magnitude larger than that for Li metal and far
exceed the minimum value (∼8.5 GPa) believed to be necessary to suppress dendrite initiation. These data suggest that LLZO
exhibits sufficient stiffness to warrant additional development as a solid electrolyte for Li batteries.
