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Amatucci, Glenn G.

Publications and source records attributed to Amatucci, Glenn G..

6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Origin of Rapid Delithiation In Secondary Particles Of LiNi 0.8 Co 0.15 Al 0.05 O 2 and LiNi y Mn z Co 1− y − z O 2 Cathodes

Abstract Most research on the electrochemical dynamics in materials for high‐energy Li‐ion batteries has focused on the global behavior of the electrode. This approach is susceptible to misleading analyses resulting from idiosyncratic kinetic conditions, such as surface impurities inducing an apparent two‐phase transformation within LiNi 0.8 Co 0.15 Al 0.05 O 2 . Here, nano‐focused X‐ray probes are used to measure delithiation operando at the scale of secondary particle agglomerates in layered cathode materials during charge. After an initial latent phase, individual secondary particles undergo rapid, stochastic, and largely uniform delithiation, which is in contrast with the gradual increase in cell potential. This behavior reproduces across several layered oxides. Operando X‐ray microdiffraction (‐XRD) leverages the relationship between Li content and lattice parameter to further reveal that rate acceleration occurs between Li‐site fraction ( x Li ) ≈0.9 and ≈0.5 for LiNi 0.8 Co 0.15 Al 0.05 O 2 . Physics‐based modeling shows that, to reproduce the experimental results, the exchange current density ( i 0 ) must depend on x Li , and that i 0 should increase rapidly over three orders of magnitude at the transition point. The specifics and implications of this jump in i 0 are crucial to understanding the charge‐storage reaction of Li‐ion battery cathodes.

25 ENERGY STORAGE↗
DOE OSTI2021

Self-Forming Thin Interphases and Electrodes Enabling 3-D Structured High Energy Density Batteries

An electrolytically in-situ formed fluoride/lithium based battery has been developed to offer a pathway to scalable reconfigurable solid state batteries of high energy density. Research into the development of novel in-situ formed chemistries encompassing the negative and positive reactive current collectors, and the bi-ion glass conductor along with electrode structure was accomplished with a focused attention on transport. The solid state in-situ batteries were fabricated with a maskless scalable patterning technique to offer a pathway to high throughput, low material loss and fabrication of complex architectures. Such development and integration enabled to achieve the 12 V bipolar batteries at > 1000 Wh/L energy density based on electrode pairs and current collectors.

25 ENERGY STORAGE↗
DOE OSTI2021

Revisiting metal fluorides as lithium-ion battery cathodes

Metal fluorides, promising lithium-ion battery cathode materials, have been classified as conversion materials due to the reconstructive phase transitions widely presumed to occur upon lithiation. We challenge this view by studying FeF 3 using X-ray total scattering and electron diffraction techniques that measure structure over multiple length scales coupled with density functional theory calculations, and by revisiting prior experimental studies of FeF 2 and CuF 2 . Metal fluoride lithiation is instead dominated by diffusion-controlled displacement mechanisms, and a clear topological relationship between the metal fluoride F- sublattices and that of LiF is established. Initial lithiation of FeF3 forms FeF2 on the particle's surface, along with a cation-ordered and stacking-disordered phase, A-Li x Fe y F 3 , which is structurally related to alpha-/beta-LiMn 2+ Fe 3+ F 6 and which topotactically transforms to B- and then C-Li x Fe y F 3 , before forming LiF and Fe. Lithiation of FeF 2 and CuF 2 results in a buffer phase between FeF 2 /CuF 2 and LiF. Overall, the resulting principles will aid future developments of a wider range of isomorphic metal fluorides.

25 ENERGY STORAGE↗
DOE OSTI2020

Mapping Competitive Reduction upon Charging in LiNi 0.8 Co 0.15 Al 0.05 O 2 Primary Particles

Side reactions involving surface reduction play a critical role in the failure of LiNi 0.8 Co 0.15 Al 0.05 O 2 to reach its theoretical capacity as a cathode material for Li-ion batteries. While macroscopic consequences are known, the underlying nanoscopic mechanisms are not fully elucidated. By coupling X-ray spectroscopy with several X-ray microscopy modalities, we have spatially resolved the extent of Ni oxidation at several states of charge and uncovered heterogeneity that is hidden when considering ensemble measurements alone. The use of morphologically controlled particles enabled high-resolution imaging of these materials, uncovering gradients of Ni oxidation states within individual primary particles. At high states of charge, these gradients revealed regions of possible oxygen deficiency extending deeper into the particle than previously observed. Surface-sensitive X-ray coupled scanning tunneling microscopy allows oxidation states to be measured at the material's surface, showing predominantly Ni II in the first atomic layer and mixtures of Ni II with Ni III /Ni IV already appearing 1.5 nm into the particle. These results reveal the subtle interplay between irreversible surface transformations and the bulk reactions that ultimately define function, which will refine strategies of surface passivation that are key to overcoming current performance limitations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

How Bulk Sensitive is Hard X-ray Photoelectron Spectroscopy: Accounting for the Cathode–Electrolyte Interface when Addressing Oxygen Redox

Sensitivity to the `bulk' oxygen core orbital makes hard X-ray photoelectron spectroscopy (HAXPES) an appealing technique for studying oxygen redox candidates. Various studies have reported an additional O 1s peak (530-531 eV) at high voltages, which has been considered a direct signature of the bulk oxygen redox process. Here, we find the emergence of a 530.4 eV O 1s HAXPES peak for three model cathodes, Li 2 MnO 3 , Li-rich NMC, and NMC 442, that shows no clear link to oxygen redox. Instead, the 530.4 eV peak for these three systems is attributed to transition metal reduction and electrolyte decomposition in the near-surface region. Claims of oxygen redox relying on photoelectron spectroscopy must explicitly account for the surface sensitivity of this technique and the extent of the cathode degradation layer.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗