Grain Boundary Softening: A Potential Mechanism for Lithium Metal Penetration through Stiff Solid Electrolytes

Title
Grain Boundary Softening: A Potential Mechanism for Lithium Metal Penetration through Stiff Solid Electrolytes
Authors
류승호Donald J. Siegel
Issue Date
2018-11
Publisher
ACS Applied Materials & Interfaces
Citation
VOL 10, NO 44-38158
Abstract
Models based on linear elasticity suggest that a solid electrolyte with a high shear modulus will suppress “dendrite” formation in batteries that use metallic lithium as the negative electrode. Nevertheless, recent experiments find that lithium can penetrate stiff solid electrolytes through microstructural features, such as grain boundaries. This failure mode emerges even in cases where the electrolyte has an average shear modulus that is an order of magnitude larger than that of Li. Adopting the solid-electrolyte Li7La3Zr2O12 (LLZO) as a prototype, here we demonstrate that significant softening in elastic properties occurs in nanoscale regions near grain boundaries. Molecular dynamics simulations performed on tilt and twist boundaries reveal that the grain boundary shear modulus is up to 50% smaller than in bulk regions. We propose that inhomogeneities in elastic properties arising from microstructural features provide a mechanism by which soft lithium can penetrate ostensibly stiff solid electrolytes.
URI
http://pubs.kist.re.kr/handle/201004/68954
ISSN
1944-8244
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KIST Publication > Article
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