Imaging voids and defects inside Li-ion cathode LiNi0.6Mn0.2Co0.2O2 single crystals

Martens, Isaac; Vanpeene, Victor; Vostrov, Nikita; Leake, Steven; Zatterin, Edoardo; Auvergniot, Jérémie; Drnec, Jakub; Richard, Marie-Ingrid; Villanova, Julie; Schülli, Tobias U.

doi:10.26434/chemrxiv-2023-p621k

Cited by 2 publications

(1 citation statement)

References 42 publications

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“…The application of recently developed highresolution X-ray and electron diffraction techniques to single-crystal cathode particles also revealed a more intricate and complex microscale misorientation framework than previously suggested. As was shown for certain nickel manganese cobalt (NMC) and LCO cathode that the microstructure of primary particles with seemingly perfect lattice structure can exhibit various degrees of tilt heterogeneities such as grain boundaries [7,23,11] which cause the development of cracks in the particles. Furthermore, it was demonstrated that the absence of domain boundaries in NMC cathode materials enhances the oxygen redox processes during prolonged cycles [10].…”

Section: Introductionmentioning

confidence: 99%

Plastic deformation of LiNi0.5Mn1.5O4 single crystals due to domain orientation dynamics

Vostrov

Martens

Colalongo

et al. 2023

Preprint

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The core principles and nanoscale mechanisms of ion deintercalation in battery cathode materials remain poorly understood, in particular, the relationship between crystallographic defects (dislocations, small angle grain boundaries, vacancies, etc.) and microscopic features of Li deintercalation. Here, we used operando scanning X-ray diffraction microscopy (SXDM) to investigate the local strain and lattice tilt inhomogeneities inside Li1−xMn1.5Ni0.5O4 cathode crystals (diameter from 1 to 2 µm) during electrochemical delithiation and lithiation. The technique has been combined to operando multi crystal X-ray diffraction (MCXD) to differentiate between inter- and intra-particle heterogeneity in the sample. Operando SXDM revealed three distinct domains within the crystal that displayed metastable angular rotations of the lattice during both of the phase transitions. These rotations, reaching up to 0.4°, likely arise due to a dynamic lattice mismatch between phases with different unit cell parameters coexisting within the particle. The persistent location of tilt boundaries implies the presence of inherent structural defects locally facilitating the defect formation. Residual misorientations were observed in the particle even after the full discharge suggesting an irreversible change of the lattice structure. Tilt boundaries, affecting ionic conductivity, may impede the rate capability and lead to localized strain, stress, and potential capacity fade due to cracking. However, the observed self-healing angular lattice reorganization could enable the coexistence of two phases in a single crystal. Understanding this phenomenon can optimize cathode material microstructure.

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Section: Introductionmentioning

confidence: 99%

Plastic deformation of LiNi0.5Mn1.5O4 single crystals due to domain orientation dynamics

Vostrov

Martens

Colalongo

et al. 2023

Preprint

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Defects and nanostrain gradients control phase transition mechanisms in single crystal high-voltage lithium spinel

Martens,

Vostrov,

Mirolo

et al. 2023

Nat Commun

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Lithiation dynamics and phase transition mechanisms in most battery cathode materials remain poorly understood, because of the challenge in differentiating inter- and intra-particle heterogeneity. In this work, the structural evolution inside Li1−xMn1.5Ni0.5O4 single crystals during electrochemical delithiation is directly resolved with operando X-ray nanodiffraction microscopy. Metastable domains of solid-solution intermediates do not appear associated with the reaction front between the lithiated and delithiated phases, as predicted by current phase transition theory. Instead, unusually persistent strain gradients inside the single crystals suggest that the shape and size of solid solution domains are instead templated by lattice defects, which guide the entire delithiation process. Morphology, strain distributions, and tilt boundaries reveal that the (Ni2+/Ni3+) and (Ni3+/Ni4+) phase transitions proceed through different mechanisms, offering solutions for reducing structural degradation in high voltage spinel active materials towards commercially useful durability. Dynamic lattice domain reorientation during cycling are found to be the cause for formation of permanent tilt boundaries with their angular deviation increasing during continuous cycling.

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Imaging voids and defects inside Li-ion cathode LiNi0.6Mn0.2Co0.2O2 single crystals

Cited by 2 publications

References 42 publications

Plastic deformation of LiNi0.5Mn1.5O4 single crystals due to domain orientation dynamics

Plastic deformation of LiNi0.5Mn1.5O4 single crystals due to domain orientation dynamics

Defects and nanostrain gradients control phase transition mechanisms in single crystal high-voltage lithium spinel

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