Lithium penetration into solid electrolytes (termed Li intrusion) limits charging rate and poses safety concerns in solid-state batteries as well as in electrolysis cells for extracting lithium metal and separating hydrogen isotopes . In brittle garnet solid electrolytes, mechanical imperfection in solid electrolytes is a key cause of Li intrusions, including surface defects such as nanoscale cracks and internal defects such as voids and grain boundaries . Metallic lithium formed during electroplating at these defects builds up stress and propagates cracks once the electrolyte fracture strength is exceeded. Electronic conductivity and trapped electrons at these defects can further promote metallic lithium nucleation and growth inside of the solid electrolyte. Conceptually, three key components contribute to the Li intrusion process: defects, which serve as the active sites for Li intrusion initiation; local current density at these defects, which acts as the driving force for electrochemical stress accumulation; and the solid electrolyte's fracture strength, which determines the critical current density at which an intrusion is initiated.