Origin of dendrite branching in solid-state batteries

The growth of lithium dendrites in solid electrolytes is a major concern in battery technology, as it often leads to material fractures, undermining device integrity and safety. Despite its significance, the mechanisms driving this process at the microscopic level remain poorly understood. This study employs advanced Dark Field X-ray Microscopy to unravel these mechanisms within a Li6.5La3Zr1.5Ta0.5O12 single-crystal electrolyte. We provide high-resolution insights into strain patterns and lattice orientation changes associated with dendrite growth. Remarkably, we report the unprecedented observation of dislocations in the immediate vicinity of dendrite tips, including one instance where a dislocation is anchored directly to a tip. This is a rare occurrence in single-crystalline ceramics and suggests a novel interplay between dendrite proliferation and dislocation formation. We hypothesize that the mechanical stress induced by dendrite expansion triggers dislocation generation. These dislocations seem to influence the fracture process, potentially influencing the directional growth and branching observed in dendrites. Our findings offer a breakthrough in understanding the microstructural dynamics of dendrite growth, providing a critical foundation for improving battery performance and safety.