Abstract
Realizing solid electrolytes with low grain-boundary (GB) resistance is critical for advancing all-solid-state batteries. High GB resistance in SEs is often attributed to deficiencies in mobile ions at these boundaries; yet, when and how these deficiencies form during synthesis remain unclear. Here, we use a unique in situ scanning transmission electron microscopy setup to guide solid electrolyte crystallization during annealing, enabling real-time observation of GB formation at the atomic scale, with Li0.33La0.56TiO3 as a model SE. We reveal an ultrathin, less than 1.5 nm thick, lithium-deficient layer that emerges at the crystallization front upon crystallization and persists as two adjacent crystals fuse to form a GB. We offer two hypotheses for the origin of the lithium-deficient layer, one based on thermodynamic stabilization and the other on kinetic constraints. Our results provide guidelines for designing synthesis strategies to reduce GB resistance in solid electrolytes.
| Original language | English |
|---|---|
| Pages (from-to) | 1858-1864 |
| Number of pages | 7 |
| Journal | ACS Energy Letters |
| Volume | 10 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 11 2025 |
Funding
This work is supported by the Mechanochemical Understanding of Solid Ion Conductors, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Science under Grant No. DE-SC0023438. The microscopy technique development was performed under DOE Basic Energy Sciences, Materials Sciences, and Engineering Division (M.C.), and microscopy was performed at ORNL’s Center for Nanophase Materials Sciences (CNMS), which is a DOE Office of Science User Facility.