Nonequilibrium Thermodynamics of Porous Electrodes
By Todd R. Ferguson, Martin Z. Bazant. 2012
306 citations recorded by the source corpus.
We reformulate and extend porous electrode theory for non-ideal active materials, including those capable of phase transformations. Using principles of non-equilibrium thermodynamics, we relate the cell voltage, ionic fluxes, and Faradaic charge-transfer kinetics to the variational electrochemical potentials of ions and electrons. The Butler-Volmer exchange current is consistently expressed in terms of the activities of the reduced, oxidized and transition states, and the activation overpotential is defined relative to the local Nernst potential. We also apply mathematical bounds on effective diffusivity to estimate porosity and tortuosity corrections. The theory is illustrated for a Li-ion battery with active solid particles described by a Cahn-Hilliard phase-field model. Depending on the applied current and porous electrode properties, the dynamics can be limited by electrolyte transport, solid diffusion and phase separation, or intercalation kinetics. In phase-separating porous electrodes, the model predicts narrow reaction fronts, mosaic instabilities and voltage fluctuations at low current, consistent with recent experiments, which could not be described by existing porous electrode models.
Subfields: Electrical and Electronic Engineering
View Paper: https://www.semanticscholar.org/paper/323c4f3b63e3c01dd2cd8518d2625c93386e6c9f
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In Electrical and Electronic Engineering
Citations in the corpus
- Validity of the Bruggeman relation for porous electrodes (2013, background): “In particular, simple hexagonal delivers directional tortuosity within 2% of the Hashin–Shtrikman lower bound [29, 30, 32].”
- Review—"Knees" in Lithium-Ion Battery Aging Trajectories (2022, unknown): “121 In a porous medium described by percolation theory, there exists a critical material parameter above which the probability of a spanning cluster, i.e., a cluster that spans the entire spatial extent of the porous medium, being formed tends toward one and below which this probability tends…”