TY - JOUR
T1 - Electrochemically induced fracture in LLZO
T2 - How the interplay between flaw density and electrostatic potential affects operability
AU - Monismith, Scott
AU - Qu, Jianmin
AU - Dingreville, Rémi
N1 - Publisher Copyright:
© 2023 Elsevier B.V.
PY - 2023/3/1
Y1 - 2023/3/1
N2 - Fracture and short circuit in the Li7La3Zr2O12 (LLZO) solid electrolyte are two key issues that prevent its adoption in battery cells. In this paper, we utilize phase-field simulations that couple electrochemistry and fracture to evaluate the maximum electric potential that LLZO electrolytes can support as a function of crack density. In the case of a single crack, we find that the applied potential at the onset of crack propagation exhibits inverse square root scaling with respect to crack length, analogous to classical fracture mechanics. We further find that the short-circuit potential scales linearly with crack length. In the realistic case where the solid electrolyte contains multiple cracks, we reveal that failure fits the Weibull model. The failure distributions shift to favor failure at lower overpotentials as areal crack density increases. Furthermore, when flawless interfacial buffers are placed between the applied potential and the bulk of the electrolyte, failure is mitigated. When constant currents are applied, current focuses in near-surface flaws, leading to crack propagation and short circuit. We find that buffered samples sustain larger currents without reaching unstable overpotentials and without failing. Our findings suggest several mitigation strategies for improving the ability of LLZO to support larger currents and improve operability.
AB - Fracture and short circuit in the Li7La3Zr2O12 (LLZO) solid electrolyte are two key issues that prevent its adoption in battery cells. In this paper, we utilize phase-field simulations that couple electrochemistry and fracture to evaluate the maximum electric potential that LLZO electrolytes can support as a function of crack density. In the case of a single crack, we find that the applied potential at the onset of crack propagation exhibits inverse square root scaling with respect to crack length, analogous to classical fracture mechanics. We further find that the short-circuit potential scales linearly with crack length. In the realistic case where the solid electrolyte contains multiple cracks, we reveal that failure fits the Weibull model. The failure distributions shift to favor failure at lower overpotentials as areal crack density increases. Furthermore, when flawless interfacial buffers are placed between the applied potential and the bulk of the electrolyte, failure is mitigated. When constant currents are applied, current focuses in near-surface flaws, leading to crack propagation and short circuit. We find that buffered samples sustain larger currents without reaching unstable overpotentials and without failing. Our findings suggest several mitigation strategies for improving the ability of LLZO to support larger currents and improve operability.
KW - Fracture
KW - LLZO
KW - Phase-field simulation
KW - Solid electrolyte
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U2 - 10.1016/j.jpowsour.2023.232646
DO - 10.1016/j.jpowsour.2023.232646
M3 - Article
AN - SCOPUS:85146091972
SN - 0378-7753
VL - 559
JO - Journal of Power Sources
JF - Journal of Power Sources
M1 - 232646
ER -