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arXiv · 1808.06164

Size-dependent phase morphologies in LiFePO4 battery particles

Daniel A. Cogswell·Martin Z. Bazant
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Abstract

Lithium iron phosphate (LiFePO$_4$) is the prototypical two-phase battery material, whose complex patterns of lithium ion intercalation provide a testing ground for theories of electrochemical thermodynamics. Using a depth-averaged (a-b plane) phase-field model of coherent phase separation driven by Faradaic reactions, we reconcile conflicting experimental observations of diamond-like phase patterns in micron-sized platelets and surface-controlled patterns in nanoparticles. Elastic analysis predicts this morphological transition for particles whose a-axis dimension exceeds the bulk elastic stripe period. We also simulate a rich variety of non-equilibrium patterns, influenced by size-dependent spinodal points and electro-autocatalytic control of thermodynamic stability.

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Daniel A. Cogswell, Martin Z. Bazant. 2018-08-19. Size-dependent phase morphologies in LiFePO4 battery particles. https://arxiv.org/abs/1808.06164

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