Synergistic multi-doping effects on the Li7La3Zr2O12 solid electrolyte for fast lithium ion conduction

Area of Science:

• Solid-state chemistry
• Materials science
• Electrochemistry

Background:

• Garnet Li7La3Zr2O12 (LLZO) is a promising solid-state electrolyte for batteries.
• Aliovalent doping, such as with Al(3+), stabilizes the desirable cubic LLZO phase.
• Dopant site preference can impede lithium ion transport.

Purpose of the Study:

• To investigate the impact of multi-doping on lithium ion transport in LLZO.
• To understand how dopant site occupancy affects ionic conductivity.
• To enhance the performance of LLZO as a solid-state electrolyte.

Main Methods:

• Combined experimental and theoretical approach.
• Structural refinement and Density Functional Theory (DFT) calculations.
• Synthesis and characterization of singly-doped and multi-doped LLZO.

Main Results:

• Al dopants in singly-doped LLZO preferentially occupy sites hindering Li+ movement.
• Multi-doping with Ta shifts Al dopants to energetically favorable sites, creating open pathways for Li+.
• Multi-doped LLZO exhibits approximately three times higher ionic conductivity (6.14 × 10^-4 S cm^-1) than singly-doped LLZO.
• Multi-doping facilitates stabilization of the cubic LLZO phase with less synthetic effort.

Conclusions:

• Multi-doping is an effective strategy to optimize dopant site occupancy in LLZO.
• This approach significantly enhances lithium ion conductivity in garnet electrolytes.
• The findings pave the way for improved solid-state battery performance.