Unraveling the Foreign-Cation Effect in UCl₃-Type Halide Solid Electrolytes for Low-Temperature All-Solid-State Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 42014689.
- Also identified by DOI 10.1038/s41467-026-70621-x.
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Abstract
UCl₃-based halide solid electrolytes have garnered increasing interest for application in all-solid-state batteries, yet their structural characteristics, chemical composition, and ion transport mechanisms remain under debate. These uncertainties hamper their rational design and broader application. Taking PrCl<sub>3</sub> as a model system, we present a comprehensive structural investigation and reveal that foreign cations (e.g., Ta<sup>5+</sup>, Zr<sup>4+</sup> and In<sup>3+</sup>) preferentially reside in amorphous matrix rather than substituting for Pr³⁺ in crystalline PrCl₃, owing to substantial mismatches in both ionic radii and coordination numbers. Importantly, the dominant pathway for fast Li⁺ conduction lies within the amorphous phase, rather than the PrCl₃ nanocrystals or their interfacial regions. Guided by these insights, Li<sub>0.5</sub>Pr<sub>0.455</sub>Ta<sub>0.179</sub>Zr<sub>0.06</sub>Cl<sub>3</sub> is rationally designed, realizing high ionic conductivity (3.10 mS cm⁻¹) and a low activation energy (0.236 eV). These improved ion-conducting properties enables battery with a capacity retention of 71.7% at 20 mA g<sup>-1</sup> and -20 °C, and a prolonged cycle life of 1350 cycles at 100 or 200 mA g<sup>-1</sup> and -10 °C. These results underscore the critical role of amorphous phase engineering in halide electrolytes and the potential of UCl₃-type systems for low-temperature all-solid-state batteries.