Visualizing Crystallization Dynamics and Transformation Pathways of Disordered Rocksalt Oxides During Thermally Activated Sol–Gel Synthesis

Cheng, Diyi [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]; Kodalle, Tim [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]; Promi, Anika T. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry]; Halder, Ansuman [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry]; Moral, Raphael F. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry; Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP (Brazil). Brazilian Synchrotron Light Laboratory (LNLS)]; Grass, Madeline [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry; University of California, Berkeley, CA (United States)]; Avvaru, Venkata S. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]; Kim, Haegyeom [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]; Sutter‐Fella, Carolin M. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry]; Zheng, Haimei [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, Berkeley, CA (United States)] (ORCID:0000000338134170)

doi:10.1002/adfm.76376

DOE OSTI · 3382424

Visualizing Crystallization Dynamics and Transformation Pathways of Disordered Rocksalt Oxides During Thermally Activated Sol–Gel Synthesis

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Abstract

Sol–gel synthesis is a wet-chemical processing route for fabricating functional materials with control over composition and microstructure at relatively low temperatures compared to conventional solid-state synthesis. While sol–gel process initiates with intermixed molecular precursors, the early-stage nucleation pathways are insufficiently understood. Here, in this study, the chemical and structural transformation of ion disordered rocksalt (DRX) Li 1.2 Mn 0.4 Ti 0.4 O 2 (LMTO), a promising cathode material for lithium batteries, is studied by multiscale characterizations. In situ heating transmission electron microscopy (TEM) using a liquid cell visualizes and identifies crystallization pathways at the nanoscale. While some regions follow a classical multi-step transition through thermodynamically stable intermediates, others exhibit a kinetic shortcut via a localized amorphous matrix to directly form the DRX structure. Macroscale Fourier transform infrared spectroscopy corroborates the findings and reveals that transition metal ions are more strongly incorporated into the acetate-coordinated network than lithium. Although in situ heating TEM captures diverse local transformation pathways, in situ synchrotron X-ray diffraction indicates that the macroscopic transformation proceeds predominantly through spinel LMTO and lithium titanates toward DRX-LMTO. The findings uncover the spatiotemporal chemical and structural transformations in sol–gel derived DRX-LMTO materials, and call for fine-tuning of such sol–gel chemistries to manipulate the crystallization pathways and achieve target material homogeneity more efficiently.

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Cheng, Diyi [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Kodalle, Tim [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Promi, Anika T. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry], Halder, Ansuman [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry], Moral, Raphael F. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry; Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP (Brazil). Brazilian Synchrotron Light Laboratory (LNLS)], Grass, Madeline [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry; University of California, Berkeley, CA (United States)], Avvaru, Venkata S. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Kim, Haegyeom [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Sutter‐Fella, Carolin M. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Molecular Foundry], Zheng, Haimei [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, Berkeley, CA (United States)] (ORCID:0000000338134170). 2026-06-10. Visualizing Crystallization Dynamics and Transformation Pathways of Disordered Rocksalt Oxides During Thermally Activated Sol–Gel Synthesis. https://doi.org/10.1002/adfm.76376

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