Mechanism of Lithium Metal Penetration through Inorganic Solid Electrolytes

5 years ago

Mechanism of Lithium Metal Penetration through Inorganic Solid Electrolytes

Till Frömling, Daniel Rettenwander, Lukas Porz, Reinhard Uecker, Stefan Berendts, Henry L. Thaman, Yet-Ming Chiang, Brian W. Sheldon, Tushar Swamy, W. Craig Carter

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. Lithium metal penetration through sulfide and oxide solid electrolytes that have been proposed for use in solid-state batteries occurs via the extension of pre-existing surface defects, of sizes down to submicron scale, due to electrodeposition-induced stresses.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/aenm.201701003