Interface-Engineered Li₇ La₃ Zr₂ O₁₂ -Based Garnet Solid Electrolytes with Suppressed Li-Dendrite Formation and...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Garnet-based solid electrolytes face challenges including high grain-boundary resistance, lithium dendrite formation, and poor electrode/lithium interfacial resistance.
• These issues hinder the practical application of garnet solid electrolytes in high-performance solid-state batteries.

Purpose of the Study:

• To engineer the interfacial architecture of garnet solid electrolytes.
• To improve lithium-ion transport and suppress lithium dendrite growth.
• To enhance the overall performance of solid-state batteries.

Main Methods:

• Incorporation of 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMP-TFSI) ionic liquid into a garnet oxide matrix.
• Formation of a continuous, 'soft' BMP-TFSI coating without added lithium salt.
• Characterization of the resulting hybrid solid electrolyte and its performance in solid-state batteries (LiNi$_{0.8}$ Co$_{0.1}$ Mn$_{0.1}$ O$_{2}$ /Li and LiFePO$_{4}$ /Li).

Main Results:

• The BMP-TFSI coating created a conducting network, facilitating Li+ transport and shifting ion conduction from point to face contacts.
• The modified microstructure suppressed lithium dendrite growth and improved interfacial compatibility and wettability with lithium metal.
• The hybrid electrolyte demonstrated a broad electrochemical window (>5.5 V) and an Li+ transference number near unity.
• Solid-state batteries utilizing the hybrid electrolyte showed superior cycling stability, low polarization, and excellent rate capability.

Conclusions:

• Interfacial architecture engineering with BMP-TFSI ionic liquid effectively addresses critical limitations of garnet solid electrolytes.
• The developed hybrid solid electrolyte enables high-performance solid-state batteries with electrochemical properties comparable to liquid electrolytes.