High-Entropy Rare Earth Halide Electrolytes with Improved Cycling Stability and Cost Effectiveness.
basic_science · Level V
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- Record sourced from PubMed, PMID 40838874.
- Also identified by DOI 10.1021/acs.nanolett.5c03417.
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Abstract
Rare earth halide solid state electrolytes (SSEs) have been attracting wide interest recently. However, the high cost of rare earth resources and poor cycling performance in all-solid-state batteries (ASSBs) hinder their practical applications. In this work, two novel high-entropy rare earth halide electrolytes, Li<sub>2.6</sub>(Y,Ho,Er,Tm,Yb)Cl<sub>5.6</sub> (HEE-1) and Li<sub>2.6</sub>(Y,Ho,Er,Tm,Yb)<sub>0.5</sub>Zr<sub>0.5</sub>Cl<sub>6.1</sub> (HEE-2), were rationally designed. Both electrolytes use five specially selected rare earth elements to achieve good cost effectiveness. These two electrolytes show high ionic conductivities of 0.52 mS·cm<sup>-1</sup> and 1.46 mS·cm<sup>-1</sup> at 25 °C, respectively. Lab-scale ASSBs incorporating HEE-1 and HEE-2 exhibit superior high-voltage compatibility and long-cycle stability. The capacity retentions reach 96.2% and 88.1% after 200 cycles, respectively, when charged to 4.5 V (vs Li<sup>+</sup>/Li) at a rate of 0.3C. Meanwhile, the cell with HEE-2 maintains 91.4% capacity after 1000 cycles between 2.5 and 4.2 V (vs Li<sup>+</sup>/Li) at a rate of 3C. The high-entropy design enables rare earth halide SSEs with better commercial potentials.