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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Electrochemically induced fracture in LLZO: How the interplay between flaw density and electrostatic potential affects operability

Fracture and short circuit in the Li 7 La 3 Zr 2 O 12 (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. Here, 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.

25 ENERGY STORAGE↗
DOE OSTI2025

Electrostatically assembled open square and checkerboard superlattices

Programmable assembly of nanoparticles into structures other than two-dimensional hexagonal lattices remains challenging. Assembling an open checkerboard or square lattice is harder to achieve compared to a close-packed hexagonal structure. Here, in this study, we introduce a unified, robust approach to assemble nanoparticles into a diverse family of two-dimensional superlattices at the liquid–air interface. Gold nanoparticles are grafted with pH-responsive, water-soluble poly(ethylene glycol) chains terminating in single bondCOOH or -NH 2 end groups, enabling control over interparticle Coloumbic interactions, while the molecular weight of grafted polymer dictates its conformation. This combined control of charges and conformation enables crystallization into checkerboard, simple-square, and body-centered honeycomb superlattices. Furthermore, tuning the pH induces structural transitions between different lattice types. This approach opens new avenues for the fabrication of colloidal superstructures with tailored architectures.

36 MATERIALS SCIENCE↗