Mechanism of Lithium Metal Penetration through Inorganic Solid Electrolytes |
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Authors: | Lukas Porz Tushar Swamy Brian W. Sheldon Daniel Rettenwander Till Frömling Henry L. Thaman Stefan Berendts Reinhard Uecker W. Craig Carter Yet‐Ming Chiang |
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Affiliation: | 1. Department of Material Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA;2. Institute of Materials Science, Technische Universit?t Darmstadt, Darmstadt, Germany;3. Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA;4. School of Engineering, Brown University, Providence, RI, USA;5. Institute of Material Science, Technische Universit?t Darmstadt, Darmstadt, Germany;6. Department of Chemistry, Technische Universit?t Berlin, Berlin, Germany;7. Leibniz Institute for Crystal Growth (IKZ), Berlin, Germany |
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Abstract: | Li deposition is observed and measured on a solid electrolyte in the vicinity of a metallic current collector. Four types of ion‐conducting, inorganic solid electrolytes are tested: Amorphous 70/30 mol% Li2S‐P2S5, polycrystalline β‐Li3PS4, and polycrystalline and single‐crystalline Li6La3ZrTaO12 garnet. The nature of lithium plating depends on the proximity of the current collector to defects such as surface cracks and on the current density. Lithium plating penetrates/infiltrates at defects, but only above a critical current density. Eventually, infiltration results in a short circuit between the current collector and the Li‐source (anode). These results do not depend on the electrolytes shear modulus and are thus not consistent with the Monroe–Newman model for “dendrites.” The observations suggest that Li‐plating in pre‐existing flaws produces crack‐tip stresses which drive crack propagation, and an electrochemomechanical model of plating‐induced Li infiltration is proposed. Lithium short‐circuits through solid electrolytes occurs through a fundamentally different process than through liquid electrolytes. The onset of Li infiltration depends on solid‐state electrolyte surface morphology, in particular the defect size and density. |
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Keywords: | critical current density defects dendrites Li‐ion batteries solid electrolytes |
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