Tension-Induced Cavitation in Li-Metal Stripping

Designing stable Li metal and supporting solid structures (SSS) is of fundamental importance in rechargeable Li-metal batteries. Yet, the stripping kinetics of Li metal and its mechanical effect on the supporting solids (including solid electrolyte interface) remain mysterious to date. Here, through nanoscale in situ observations of a solid-state Li-metal battery in an electron microscope, two distinct cavitation-mediated Li stripping modes controlled by the ratio of the SSS thickness (t) to the Li deposit's radius (r) are discovered. A quantitative criterion is established to understand the damage tolerance of SSS on the Li-metal stripping pathways. For mechanically unstable SSS (t/r < 0.21), the stripping proceeds via tension-induced multisite cavitation accompanied by severe SSS buckling and necking, ultimately leading to Li trapping or dead Li formation; for mechanically stable SSS (t/r > 0.21), the Li metal undergoes nearly planar stripping from the root via single cavitation, showing negligible buckling. This work proves the existence of an electronically conductive precursor film coated on the interior of solid electrolytes that however can be mechanically damaged, and it is of potential importance to the design of delicate Li-metal supporting structures to high-performance solid-state Li-metal batteries.

Automated summary

Designing stable Li metal and supporting solid structures (SSS) is crucial for rechargeable Li-metal batteries. Through in situ observations of a solid-state Li-metal battery, two distinct modes of Li stripping controlled by the SSS thickness to Li deposit's radius ratio are discovered. A quantitative criterion is established to understand the damage tolerance of SSS on the Li-metal stripping pathways. This work highlights the importance of designing delicate Li-metal supporting structures for high-performance solid-state Li-metal batteries.