Localized Electrolyte Grain Engineering to Suppress Li Intrusion in All-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium (Li) intrusion significantly degrades the cycling durability and rate capability of all-solid-state lithium metal batteries.
• Conventional solid electrolyte (SE) engineering, like doping, has limited success in suppressing Li intrusion due to difficulties in optimizing multiple macroscopic properties.
• Current methods often involve complex, trial-and-error processes for SE modification.

Purpose of the Study:

• To develop a new strategy for engineering solid electrolytes (SEs) at the grain-aggregate level, moving beyond conventional crystalline-scale modifications.
• To enhance the cycling durability and rate capability of all-solid-state lithium metal batteries by effectively suppressing Li intrusion.
• To introduce a scalable and efficient method for SE modification.

Main Methods:

• A scalable chemical approach utilizing a thermodynamic-favored anion exchange reaction was employed to create an amorphous metal compound layer on argyrodite-type electrolyte grains.
• A localized grain engineering concept was introduced, combining modified and unmodified electrolyte grains to form aggregates with optimized macroscopic properties.
• The performance of these localized grain-engineered electrolyte aggregates was evaluated in all-solid-state lithium metal battery cells.

Main Results:

• The engineered amorphous metal compound layer effectively modified the surface properties of the electrolyte grains.
• Localized grain-engineered electrolyte aggregates demonstrated significantly enhanced lithium reversibility.
• These engineered aggregates successfully suppressed Li intrusion under practical operating conditions, with a Li||NCM cell achieving over 2000 stable cycles at 1.6 mA cm⁻².

Conclusions:

• Optimizing solid electrolytes at the grain-aggregate level offers a promising alternative to conventional crystalline-scale engineering for suppressing Li intrusion.
• The developed localized grain engineering strategy provides a highly effective and scalable method for improving the performance of solid-state lithium metal batteries.
• This approach significantly enhances battery cycling durability and rate capability, paving the way for practical applications.