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

Abstract

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

Novelty Detection in the Design of Synthesis of Energy Storage Materials: a Case Study of Garnet-Structured Solid Electrolytes

“…Authors assumed that La 2+x Zr 2 2x Ta x O 7 (x = 0.4) can effectively act as a precursor oxide because of the same molar ratio of La:Zr:Ta as in TaO 2:5 system). The alternative approach was used in [68], where authors have introduced the time-temperature phase diagram for thin films of garnet electrolytes in order to efficiently represent the phase formation process. This information can be related to the problems concerned with the surface energy of the studied system, however, the more precise thermodynamic-based investigations are needed.…”

Uncovering the Network Modifier for Highly Disordered Amorphous Li‐Garnet Glass‐Ceramics

“…[27,28] To ensure that the oxide-based cathode materials remain in their high-capacity phases with conventional solid electrolytes such as LLZO, unconventional manufacturing strategies are required to either shorten the sintering time by rapid thermal annealing, see Refs. [29][30][31] and therefore minimize the interfacial reaction, or maintain the co-processing temperature below 600 °C, [32] which is ≈400 °C lower than the classic co-sintering temperature, see Refs. [27,28] for details.…”