Crystallization Kinetics as a Design Lever for High-Performance Halide Solid Electrolytes Obtained by Scalable...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Halide solid electrolytes (SEs), such as Li3InCl6, are crucial for developing high-energy all-solid-state lithium batteries (ASSLBs).
• Solvent-mediated synthesis is a scalable method for producing Li3InCl6, but controlling crystallization kinetics is vital for optimal material properties.
• Existing synthesis methods often result in SE materials with suboptimal performance due to a lack of understanding of critical parameters.

Purpose of the Study:

• To systematically investigate how evaporative crystallization temperature and environment affect the phase purity, microstructure, and defect chemistry of Li3InCl6 SE.
• To understand the impact of these factors on the transport properties and electrochemical performance of Li3InCl6.
• To identify optimal synthesis conditions for high-performance halide solid electrolytes.

Main Methods:

• Investigated the influence of varying crystallization temperatures (20-60 °C) and environments (ambient vs. non-ambient).
• Analyzed phase purity, microstructure, and defect chemistry using advanced characterization techniques.
• Measured ionic conductivity and evaluated electrochemical performance in all-solid-state lithium battery cells.

Main Results:

• Slow crystallization under ambient conditions and moderate temperatures (20-60 °C) produced phase-pure Li3InCl6 with the highest reported ionic conductivity for water-mediated routes (3.97 mS cm⁻¹ with carbon, 2.98 mS cm⁻¹ without).
• High temperatures and non-ambient processing led to structural defects, increased grain-boundary impedance, and impurity incorporation, significantly reducing conductivity.
• Optimized Li3InCl6 enabled full cells to deliver high capacity at 20 °C with excellent stability (>95%) at high areal loading and low interfacial impedance.

Conclusions:

• Optimal crystallization parameters are critical for achieving phase-pure Li3InCl6 with superior ionic conductivity.
• Controlled synthesis via solvent-mediated routes can overcome limitations in halide SE performance for next-generation ASSLBs.
• This study provides essential insights for designing and synthesizing high-performance solid electrolytes for advanced battery technologies.