Reaction Pathway Informed Strategy for Fast Solid-State Synthesis of Garnet-Type Solid Electrolyte

The widespread adoption of materials synthesized via solid-state methods is often hindered by the high costs associated with long reaction durations and elevated processing temperatures. In this study, we use the solid-state electrolyte Li7La3Zr2O12 (LLZO) as a model material to investigate the solid-state reaction pathway, identifying intermediates and exploring strategies to accelerate forward reactions while mitigating impurity formation. By manipulating reaction equilibria─specifically through the control of lithium precursor availability, we successfully suppress reverse reactions and achieve phase-pure LLZTO with electrochemical properties consistent with literature benchmarks, using a calcination time of only 30 min, representing a 10-fold reduction in reaction time. Operando and ex-situ characterization techniques were employed to probe the reaction dynamics at both surface and bulk levels, providing mechanistic insights. This work not only introduces a rapid approach to synthesizing LLZO, but also offers a generalizable framework that can be adapted for developing and optimizing other solid-state materials.