Garnet-Based Solid-State Li Batteries with High-Surface-Area Porous LLZO Membranes

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Garnet-based solid-state lithium batteries, utilizing Li₇La₃Zr₂O₁₂ (LLZO), offer nonflammable, high energy density storage.
• Commercialization is hindered by void formation at the LLZO/Li interface, leading to dendrite growth and poor cycling stability at practical current densities.
• Developing thin LLZO electrolytes is crucial for achieving high energy density in these batteries.

Purpose of the Study:

• To address void formation and dendrite issues in garnet-based solid-state batteries.
• To develop a facile fabrication method for thin, porous LLZO membranes.
• To enhance the cycling stability and energy density of solid-state lithium batteries.

Main Methods:

• Fabrication of self-standing, 50 μm thick, porous LLZO membranes using small pore formers (ca. 1.5 μm).
• Utilized ultrafast sintering with rapid heating/cooling rates (ca. 50 °C/s) to control porosity and prevent overdensification.
• Characterized membrane properties including pore size (ca. 2.3 μm), porosity (51%), and specific surface area (1.3 μm^-1).

Main Results:

• Achieved the highest reported specific surface area for LLZO membranes (1.3 μm^-1).
• The porous LLZO membranes significantly increased the Li/LLZO contact area, effectively mitigating void formation.
• Demonstrated exceptional cycling stability in a symmetrical Li/LLZO/Li cell, exceeding 600 hours at 0.1 mA cm^-2.

Conclusions:

• The developed methodology offers a facile approach to fabricating porous LLZO membranes for advanced solid-state batteries.
• The increased contact area and mitigated void formation contribute to enhanced cycling stability.
• This work provides a promising pathway for the commercialization of high-energy density, safe garnet-based solid-state lithium batteries.