Garnet-Type Solid-State Electrolyte with Tailored Lithium Compatibility for High Performance All-Solid-State Lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Garnet-type Li7La3Zr2O12 (LLZO) solid-state electrolytes (SSEs) offer high ionic conductivity for all-solid-state batteries.
• Interfacial compatibility between LLZO and lithium metal electrodes remains a challenge for practical battery deployment.

Purpose of the Study:

• To design and synthesize novel garnet-type SSEs (Li7La3Zr2-xScxO12-xFx, LLZSOF) with enhanced lithium metal compatibility.
• To investigate the effect of scandium and fluorine doping on the structural, electrochemical, and interfacial properties of LLZO.

Main Methods:

• Synthesis of LLZSOF materials with varying Sc and F content (x = 0-0.20).
• Characterization of crystal structure, ionic conductivity, and electrochemical stability.
• Fabrication and testing of symmetric cells and all-solid-state lithium metal batteries (ASLMBs).

Main Results:

• Optimized LLZSOF-0.15 composition demonstrated strong interfacial contact with lithium metal, inhibiting Li+/H+ exchange.
• Scandium substitution increased lithium content and improved reduction stability.
• LLZSOF-0.15 based symmetric cells achieved a critical current density of 1.9 mA cm-2.
• ASLMBs using LLZSOF-0.15 exhibited excellent cyclability with high capacity retention for LiFePO4 and NCM cathodes.
• Pouch cells demonstrated high Coulombic efficiency (>99.5%) and capacity retention (>94.9%) over 120 cycles.

Conclusions:

• The developed LLZSOF SSEs exhibit superior interfacial compatibility with lithium metal electrodes.
• This material design approach promotes the development of advanced garnet SSEs for scalable all-solid-state battery applications.