Constructing an anion-capturing interface to achieve Li⁺ cross-phase transport in composite solid electrolytes.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Solid-state lithium metal batteries offer enhanced safety but are limited by low ionic conductivity in solid electrolytes.
• Charged interfaces and concentration gradients hinder lithium-ion (Li+) transport and battery performance.

Purpose of the Study:

• To engineer an anion-capturing interface on solid electrolytes to enhance Li+ conductivity and battery performance.
• To address interfacial challenges in solid-state lithium metal batteries.

Main Methods:

• A sol-gel method was used to create an FeF3-based anion-capturing interface on a Li6.5La3Zr1.5Ta0.5O12 (LLTO) solid electrolyte surface.
• Composite solid electrolytes were fabricated by incorporating the modified LLTO with a polymer.

Main Results:

• The FeF3 interface promoted Li-salt dissociation and facilitated Li+ migration, reducing interfacial resistance.
• The composite solid electrolyte achieved an ionic conductivity of 1.1×10-4 S/cm² and a Li+ transference number of 0.75.
• Li symmetrical batteries demonstrated stable Li plating/stripping for over 1300 hours with low polarization.
• Solid-state batteries with LiFePO4 cathodes exhibited a specific capacity of 152.8 mAh/g at 1.0 C with 96% retention after 600 cycles.

Conclusions:

• Interface engineering with anion-capturing FeF3 is a promising strategy to overcome interfacial limitations in solid electrolytes.
• The developed composite solid electrolyte shows potential for high-performance solid-state lithium metal batteries.