Time–Temperature–Transformation (TTT) Diagram of Battery‐Grade Li‐Garnet Electrolytes for Low‐Temperature Sustainable Synthesis

Efficient and affordable synthesis of Li+ functional ceramics is crucial for the scalable production solid electrolytes batteries. Li‐garnet Li7La3Zr2O12−d (LLZO), especially its cubic phase (cLLZO), attracts attention due to high conductivity wide electrochemical stability window. However, sintering temperatures raise concerns about cathode interface stability, costs, energy consumption manufacture. We show an alternative “sinter‐free” route stabilize cLLZO as films at half sinter temperature. Specifically, we establish a time–temperature–transformation (TTT) diagram which captures amorphous‐to‐crystalline LLZO transformation based on crystallization enthalpy analysis confirm stabilization thin‐film record low 500 °C. Our findings pave way low‐temperature processing via TTT diagrams, can be used battery cell design targeting reduced carbon footprints in manufacturing.