Multi-Ion Doped Zr-Based Halide Solid Electrolytes for High-Performance All-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Zr-based halide solid-state electrolytes (SSEs) offer commercial advantages like cost-effectiveness and mechanical flexibility.
• Current limitations include low ionic conductivity at room temperature and poor compatibility with high-voltage cathodes.

Purpose of the Study:

• To develop a novel high-entropy SSE (HESSEO) with improved ionic conductivity and electrochemical stability.
• To investigate the synergistic effects of doping with multiple metal ions (Nb, Mo, Ta, Hf) and oxygen.

Main Methods:

• Synthesis of oxygen-doped high-entropy SSE (HESSEO, Li2.89Zr0.72Nb0.07Mo0.07Ta0.07Hf0.07Cl4.9O1.1) by incorporating M and O ions into Li2ZrCl6.
• Characterization of ionic conductivity and electrochemical performance.
• Density Functional Theory (DFT) calculations to understand Li+ diffusion mechanisms.

Main Results:

• HESSEO achieved a high ionic conductivity of 2.13 mS cm-1 at room temperature.
• DFT calculations revealed enhanced Li+ diffusion coefficients and lower energy barriers in HESSEO compared to Li2ZrCl6.
• All-solid-state batteries (ASSBs) using HESSEO demonstrated excellent cycling stability, retaining 78.8% capacity after 1000 cycles at 2C/4.3V and stable operation at 4.5V.

Conclusions:

• The multi-ion synergistic design effectively enhances ionic conductivity and high-voltage stability in halide SSEs.
• HESSEO presents a promising strategy for developing commercially viable all-solid-state batteries.
• This work offers a practical approach for advancing next-generation energy storage solutions.