Failure of all solid-state batteries

Solid-state batteries comprising a ceramic electrolyte and Li metal anode have the potential to deliver enhanced safety along with higher specific energies compared to liquid electrolyte Li-ion batteries. However, stiff, and strong ceramic electrolytes can suffer short circuits resulting from the penetration of Li filaments through the ceramic at charging currents above a critical current density. This is remarkable since the yield strength of Li is on the order of a few MPa while the ceramic electrolytes have strengths of many 100s of MPa and moduli in the GPa range. The failure of these Li-ion cells occurs via two interconnected processes: (i) formation of voids at the Li electrode/electrolyte interface and (ii) growth of Li filaments, that emanate from vicinity of these voids, into the electrolyte. Our work has involved developing coupled electrochemical-mechanical variational principles to understand how the electrochemistry of these cells drives mechanical failure. The focus is on developing an understanding of how well-established ideas such as Butler-Volmer kinetics need to be modified in the context of these solid-state batteries. The numerical solution of the variational principles provides insights into experimental observations, but numerous uncertainties remain with regards the microscale properties of the Li and solid electrolytes as well the mechanisms coupling mechanical deformations and electrochemistry.

Videos showing the propagation of Li dendrites in the solid electrolyte. The top video shows the flux fields within the electrolyte while the bottom one shows the associated stress fields.

Growth and collapse of voids in Li anodes. The video at the bottom shows predictions of the coupled flux fields in the electrolyte and the consequent growth of voids around an impurity particle in the Li electrode.

Key Literature

S.S. Shishvan, N.A. Fleck, R.M. McMeeking and V.S. Deshpande (2020), Dendrites as climbing dislocations in ceramic electrolytes: initiation of growth, Journal of Power Sources, 456, 227989.

S.S. Shishvan, N.A. Fleck, R.M. McMeeking and V.S. Deshpande (2020), Dendrites as climbing dislocations in ceramic electrolytes: rate of growth, Acta Materialia, 196, 444-455.

S.S. Shishvan, N.A. Fleck, and V.S. Deshpande (2021), The initiation of void growth during stripping of Li electrodes in solid electrolyte cells, Journal of Power Sources, 488, 229437.

Resources

Videos