High-Entropy-Driven Moderate Lattice Distortion Improves Ionic Conductivity and High-Voltage Stability of Halide...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Developing high-energy all-solid-state batteries (ASSBs) requires solid-state electrolytes (SSEs) with high ionic conductivity and high-voltage stability.
• Conventional methods for improving SSEs often involve trade-offs between ionic conductivity and voltage stability.
• Existing strategies like cation substitution or anion engineering face limitations in simultaneously achieving desired properties.

Purpose of the Study:

• To design and synthesize novel halide SSEs using a high-entropy strategy to overcome limitations of conventional methods.
• To investigate the relationship between high-entropy-induced lattice distortion and ionic conductivity/voltage stability in SSEs.
• To evaluate the performance of the developed SSEs in high-energy ASSBs.

Main Methods:

• Employed a high-entropy strategy to synthesize Li_3-4xIn_1-6xFe_xY_xZr_2xHf_2xCl₆ through multication substitution in Li₃InCl₆.
• Characterized the synthesized material (HE-LIC) using experimental techniques and theoretical calculations.
• Fabricated ASSBs using the HE-LIC electrolyte and a LiCoO₂ cathode for performance testing.

Main Results:

• Synthesized Li_2.92In_0.88Fe_0.02Y_0.02Zr_0.04Hf_0.04Cl₆ (HE-LIC) exhibiting moderate lattice distortion.
• Achieved a high ionic conductivity of 1.136 mS cm^-1 at 25 °C and improved high-voltage stability.
• Demonstrated excellent electrochemical performance in ASSBs with LiCoO₂ cathodes, including high discharge capacity and stable cycling at 4.5 V and 4.6 V.

Conclusions:

• The high-entropy strategy effectively enables moderate lattice distortion, enhancing Li⁺ conduction and inhibiting Cl^- oxidation.
• HE-LIC shows significant potential as an advanced SSE for high-energy ASSBs.
• This work highlights the promise of high-entropy materials design for developing next-generation solid-state batteries.