Interactions between organic binder and boron sintering aid in the slurry of LLZTO electrolyte

This research investigates challenges associated with gelation in Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZTO) slurry preparation for solid-state Li-ion batteries. Gelation arises from a cross-linking reaction between the sintering aid , boron oxide (B 2 O 3 ), and the poly(vinyl butyral) (PVB) binder. With increasing B 2 O 3 content, LLZTO slurry viscosity dramatically rises, resulting in unsuitable solid-like behavior for tape casting. The alkaline nature of LLZTO powder intensifies cross-linking, a phenomenon confirmed through boron-11 nuclear magnetic resonance spectroscopy. To mitigate gelation, diol compounds, such as ethylene glycol, are introduced to deactivate B 2 O 3 -PVB cross-linking, with selection guided by support from density functional theory-based simulations.