Electrochemically Stable Li_3-In_1-HfCl₆ Halide Solid Electrolytes for All-Solid-State Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Halide solid electrolytes (SEs) offer high ionic conductivity and oxidative stability, crucial for energy storage.
• Aliovalent substitution improves ionic conductivity but often reduces electrochemical stability in halide SEs.

Purpose of the Study:

• To investigate hafnium (Hf) substitution in Li3InCl6 solid electrolytes.
• To enhance ionic conductivity and electrochemical stability of halide SEs.
• To develop high-performance all-solid-state batteries.

Main Methods:

• Synthesized Hf-substituted Li3InCl6 (Li3-xIn1-xHfxCl6) solid electrolytes.
• Characterized ionic conductivity and electrochemical stability.
• Fabricated and tested all-solid-state batteries using the optimized SE.

Main Results:

• Low concentrations of Hf substitution (0.1 ≤ x ≤ 0.5) enhanced ionic conductivity without decreasing electrochemical stability.
• Li2.7In0.7Hf0.3Cl6 exhibited a high ionic conductivity of 1.28 mS cm⁻¹ and a wide electrochemical stability window (2.68–4.22 V).
• All-solid-state batteries demonstrated high discharge capacity and good cycling stability at 25 °C.

Conclusions:

• Hf substitution is an effective strategy for optimizing halide solid electrolytes.
• The developed Li2.7In0.7Hf0.3Cl6 shows promise for advanced all-solid-state batteries.
• Crystal structure regulation via aliovalent substitution is key for designing novel halide SEs.