Mechanical regulation of lithium intrusion probability in garnet solid electrolytes

• Published in: Nature energy 2023-03, Vol.8 (3), p.241-250
• Main Authors: McConohy, Geoff, Xu, Xin, Cui, Teng, Barks, Edward, Wang, Sunny, Kaeli, Emma, Melamed, Celeste, Gu, X. Wendy, Chueh, William C.
• Format: Article
• Language: English
• Subjects: 639/166/988; 639/301/299/161/891; 639/301/299/891; Cantilever beams; Chemical reactions; Chemical reduction; Compressive properties; Contact force; Dendrites; Economics and Management; Electrochemistry; Electrolytes; Energy; Energy Policy; Energy Storage; Energy Systems; Intrusion; Ions; Lithium; Lithium batteries; Metals; Molten salt electrolytes; Plating; Rechargeable batteries; Renewable and Green Energy; Scanning electron microscopy; Solid electrolytes; Statistical analysis; Statistics; Weibull distribution
• ISSN: 2058-7546; 2058-7546
• DOI: 10.1038/s41560-022-01186-4

Solid electrolytes in rechargeable lithium-metal batteries are susceptible to lithium-metal short circuiting during plating, and the root cause is under debate. In this work, we investigated statistically the effect of locally and globally applied stress on lithium penetration initiation in Li 6.6 La 3 Ta 0.4 Zr 1.6 O 12 (LLZO) via operando microprobe scanning electron microscopy. Statistical analysis revealed that the cumulative probability of intrusion as a function of lithium-metal diameter follows a Weibull distribution. Upon increasing the microprobe–LLZO contact force, the characteristic failure diameter of lithium metal decreases significantly. In addition, we control the direction of intrusion propagation by applying a 0.070% compressive strain via operando cantilever beam-bending experiments. Overall, we find that the root cause of lithium intrusion into the electrolyte is a combination of current focusing and the presence of nanoscale cracks, rather than electronic leakage or electrochemical reduction. These insights highlight the mechanical tunability of electrochemical plating reactions in brittle solid electrolytes. The root cause of lithium dendrites during battery cycling is of fundamental interest. By performing operando microprobe experiments and statistical analyses, the authors report that lithium dendrites are initiated via nanoscale mechanical defects and can be manipulated via globally applied stresses.