Electrolyte

Lithium Intrusion In Garnet (LLZO) Solid Electrolytes

Electrolyte

Lithium Intrusion In Garnet (LLZO) Solid Electrolytes

Mechanical forces can propagate nanoscale cracks and lithium intrusion in LLZO electrolytes Lithium-metal batteries with solid electrolytes are at risk of short-circuiting due to lithium-metal plating. A detailed investigation by Stanford University researchers, involving 56 lithium plating tests on unblemished LLZO (lithium lanthanum zirconium oxide) surfaces, provides new insights into this issue (Fig A below). The team's findings suggest that the primary causes of lithium intrusion into garnet-type electrolytes are current focusing effects and the existence of nanoscale surface cracks. These factors contribute more to the problem than previously theorized causes like electronic leakage or electrochemical reduction. The study also reveals that the likelihood of intrusion is statistically related to the size of the lithium-metal (diameter), following a Weibull distribution (Fig B below). This indicates that initiation of intrusion tends to occur at sites with more focused current or concentrated microstructural defects within the LLZO. Nano-cracks (pre-existing or generated via external load) are the root cause of lithium-metal intrusions in lithium garnet electrolytes, the propagation of these nanocracks can be controlled mechanically. A fundamental understanding of this intrusion process will enable the development and manufacturing of next-generation solid-state batteries that can remain stable over higher charge rates.

Similarly, the team led by Yet-Ming Chiang at MIT previously demonstrated that lithium dendrites form due to the mechanical failure of electrolytes (LLZTO). Their research further revealed that controlling mechanical stresses can effectively guide the trajectory of these dendrites. Academia | P. 224 Source: McConohy, Xu, Cui, Barks, Wang, Kaeli, Melamed, Gu, Chueh and Fincher, Athanasiou, Gilgenbach, Wang, Sheldon, Carter, Chiang

Extracted from the PDF; charts and images may read imperfectly.