A phase field electro-chemo-mechanical model for void evolution in all-solid-state batteries

EUROMECH 617 Colloquium. MULTISCALE MECHANICS, MULTIPHYSICS MODELING AND SIMULATIONS FOR ENERGY STORAGE
29-31 August 2022, Lake of Garda, Italy
https://617.euromech.org/

A phase field electro-chemo-mechanical model for predicting void evolution at the Li-electrolyte interface in all-solid-state batteries
Emilio Martínez-Pañeda. Imperial College London
Co-authors: Ying Zhao, Runzi Wang

Paper: https://doi.org/10.1016/j.jmps.2022.104999

Abstract
Solid-state batteries are arguably the most promising development in battery technology [1]. However, commercialisation is hindered by the nucleation and growth of dendrites, needle-like structures between electrodes that short circuit the batteries. The nucleation of dendrites is a two-stage process. First, during stripping, voids form at the anode, adjacent to the electrode-electrolyte interface. Those voids lead to a reduction in the contact area between the electrode and the solid electrolyte and trigger the development of ‘hot-spots’, regions of high current that arise at void corners. Then, during plating, dendrites nucleate in those hot-spot regions. It has been argued that pressure can be introduced to maintain a void-free electrode-electrolyte interface and consequently suppress dendrite formation [3]. Thus, there is a need to develop electro-chemo-mechanical models capable of predicting void evolution and the development of hot spots as a function of the material, applied pressure and charge.

In this work, we present the first phase field formulation for predicting void evolution in all-solid state batteries and conduct relevant numerical experiments on solid state batteries using Li metal as anode material [3]. The phase field order parameter describes the evolution of the void-Li metal interface, as driven by the nucleation and annihilation of Li lattice sites. Creep effects are captured by using a viscoplastic formulation for Li, and the interplay between vacancy diffusion, oxidation and creep deformation is quantified as a function of the applied pressure and current. Moreover, the electrolyte current distribution is solved for and thus ‘hot-spots’ are predicted for electrode-electrolyte systems developing multiple voids and undergoing several stripping and plating cycles. We show that the model can capture the main trends observed in the experiments and be used to map safe regimes of operation.

REFERENCES
[1] J. Janek, W.G. Zeier, A solid future for battery development, Nature Energy 1(9), 1-4 (2016)
[2] J. Kasemchainan, S. Zekoll, D.S. Jolly, Z. Ning, G.O. Hartley, J. Marrow, P. Bruce. Critical stripping current leads to dendrite formation on plating in lithium anode solid electrolyte cells. Nature Materials 18, 1105-1111 (2019).
[3] Y. Zhao, R. Wang, E. Martínez-Pañeda. A phase field electro-chemo-mechanical formulation for predicting void evolution at the Li-electrolyte interface in all-solid-state batteries. Journal of the Mechanics and Physics of Solids 67, 104999 (2022)

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