Li-ion batteries are yet to realize their full promise because of challenges in the design and construction of electrode architectures that allow for their entire interior volumes to be reversibly accessible for ion storage. Electrodes constructed from the same material and with the same specifications that differ only in terms of dimensions and geometries of the constituent particles can show surprising differences in polarization, stress accumulation, and capacity fade. Here, using operando synchrotron X-ray diffraction (XRD) and energy dispersive X-ray diffraction (EDXRD), we probe the mechanistic origins of the remarkable particle-geometry-dependent modification of lithiation-induced phase transformations in V2O5 as a model phase-transforming cathode. A pronounced modulation of phase coexistence regimes is observed as a function of particle geometry. Specifically, a metastable phase is stabilized for nanometer-sized spherical V2O5 particles to circumvent the formation of large misfit strains. Spatially resolved EDXRD measurements demonstrate that particle geometries strongly modify the tortuosity of the porous cathode architecture. Greater ion transport limitations in electrode architectures comprising micron-sized platelets result in considerable lithiation heterogeneities across the thickness of the electrode. These insights establish particle-geometry-dependent modification of metastable phase regimes and electrode tortuosity as key design principles for realizing the promise of intercalation cathodes.

How crystallite geometries determine the electrochemical performance of porous electrodes: Insights from Multiscale Operando studies of a phase-separating intercalation host

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.